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Table of Cont ents
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 10-K

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the fiscal year ended December 31, 2020
or
☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the transition period from to
Name of Registrant, State of Incorporation, Address of Principal Executive Offices, Telephone Number, Commission File Number, IRS Employer Identification Number
ALLIANT ENERGY CORPORATION
(a Wisconsin Corporation)
4902 N. Biltmore Lane
Madison, Wisconsin 53718
Telephone (608) 458-3311
Commission File Number - 1-9894
IRS Employer Identification Number - 39-1380265
INTERSTATE POWER & LIGHT COMPANY
(an Iowa corporation)
Alliant Energy Tower
Cedar Rapids, Iowa 52401
Telephone (319) 786-4411
Commission File Number - 1-4117
IRS Employer Identification Number - 42-0331370
WISCONSIN POWER & LIGHT COMPANY
(a Wisconsin corporation)
4902 N. Biltmore Lane
Madison, Wisconsin 53718
Telephone (608) 458-3311
Commission File Number - 0-337
IRS Employer Identification Number - 39-0714890
This combined Form 10-K is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company. Information contained in the Form 10-K relating to Interstate Power and Light Company and Wisconsin Power and Light Company is filed by each such registrant on its own behalf. Each of Interstate Power and Light Company and Wisconsin Power and Light Company makes no representation as to information relating to registrants other than itself.
Securities registered pursuant to Section 12(b) of the Act:
Alliant Energy Corporation, Common Stock, $0.01 Par Value, Trading Symbol LNT, Nasdaq Global Select Market
Interstate Power and Light Company, 5.100% Series D Cumulative Perpetual Preferred Stock, $0.01 Par Value, Trading Symbol IPLDP, Nasdaq Global Select Market
Securities registered pursuant to Section 12(g) of the Act: None
Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.
Alliant Energy Corporation - Yes ☒ No ☐
Interstate Power and Light Company - Yes ☒ No ☐
Wisconsin Power and Light Company - Yes ☒ No ☐
Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.
Alliant Energy Corporation - Yes ☐ No ☒
Interstate Power and Light Company - Yes ☐ No ☒
Wisconsin Power and Light Company - Yes ☐ No ☒
Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrants were required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.
Alliant Energy Corporation - Yes ☒ No ☐
Interstate Power and Light Company - Yes ☒ No ☐
Wisconsin Power and Light Company - Yes ☒ No ☐
Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).
Alliant Energy Corporation - Yes ☒ No ☐
Interstate Power and Light Company - Yes ☒ No ☐
Wisconsin Power and Light Company - Yes ☒ No ☐
Indicate by check mark whether the registrant is a large accelerated filer, accelerated filer, non-accelerated filer, smaller reporting company, or emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
Alliant Energy Corporation - Large Accelerated Filer ☒ Accelerated Filer ☐ Non-accelerated Filer ☐ Smaller Reporting Company ☐ Emerging Growth Company ☐
Interstate Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth Company ☐
Wisconsin Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth Company ☐
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.
Alliant Energy Corporation ☐
Interstate Power and Light Company ☐
Wisconsin Power and Light Company ☐
Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (§ 15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.
Alliant Energy Corporation ☒
Interstate Power and Light Company ☐
Wisconsin Power and Light Company ☐
Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).
Alliant Energy Corporation - Yes ☐ No ☒
Interstate Power and Light Company - Yes ☐ No ☒
Wisconsin Power and Light Company - Yes ☐ No ☒
The aggregate market value of the voting and non-voting common equity held by nonaffiliates as of June 30, 2020:
Alliant Energy Corporation - $11.9 billion
Interstate Power and Light Company - $0
Wisconsin Power and Light Company - $0
Number of shares outstanding of each class of common stock as of January 31, 2021:
Alliant Energy Corporation, Common Stock, $0.01 par value, 249,881,050 shares outstanding
Interstate Power and Light Company, Common Stock, $2.50 par value, 13,370,788 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)
Wisconsin Power and Light Company, Common Stock, $5 par value, 13,236,601 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)
DOCUMENTS INCORPORATED BY REFERENCE
Portions of the Proxy Statement relating to Alliant Energy Corporation’s 2021 Annual Meeting of Shareowners are, or will be upon filing with the Securities and Exchange Commission, incorporated by reference into Part III hereof.

Table of Cont ents
TABLE OF CONTENTS

| Page Number
Definitions |  | 1
Forward-looking Statements |  | 1
Website Access to Reports |  | 3
Part I. | Item 1. Business | 3
| Item 1A. Risk Factors | 14
| Item 1B. Unresolved Staff Comments | 19
| Item 2. Properties | 19
| Item 3. Legal Proceedings | 21
| Item 4. Mine Safety Disclosures | 21
| Information About Executive Officers | 21
Part II. | Item 5. Market for Registrants’ Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities | 22
| Item 6. Selected Financial Data | 23
| Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations | 23
| Item 7A. Quantitative and Qualitative Disclosures About Market Risk | 39
| Item 8. Financial Statements and Supplementary Data | 39
|  | Alliant Energy Corporation | 40
|  | Interstate Power and Light Company | 46
|  | Wisconsin Power and Light Company | 52
|  | Combined Notes to Consolidated Financial Statements | 58
|  |  | 1. Summary of Significant Accounting Policies | 58
|  |  | 2. Regulatory Matters | 63
|  |  | 3. Property, Plant and Equipment | 67
|  |  | 4. Jointly-owned Electric Utility Plant | 68
|  |  | 5. Receivables | 68
|  |  | 6. Investments | 69
|  |  | 7. Common Equity | 70
|  |  | 8. Preferred Stock | 70
|  |  | 9. Debt | 70
|  |  | 10. Leases | 72
|  |  | 11. Revenues | 73
|  |  | 12. Income Taxes | 74
|  |  | 13. Benefit Plans | 76
|  |  | 14. Asset Retirement Obligations | 86
|  |  | 15. Derivative Instruments | 86
|  |  | 16. Fair Value Measurements | 87
|  |  | 17. Commitments and Contingencies | 89
|  |  | 18. Segments of Business | 92
|  |  | 19. Related Parties | 94
| Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure | 95
| Item 9A. Controls and Procedures | 95
| Item 9B. Other Information | 97
Part III. | Item 10. Directors, Executive Officers and Corporate Governance | 97
| Item 11. Executive Compensation | 97
| Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters | 97
| Item 13. Certain Relationships and Related Transactions, and Director Independence | 98
| Item 14. Principal Accounting Fees and Services | 98
Part IV. | Item 15. Exhibits, Financial Statement Schedules | 99
| Item 16. Form 10-K Summary | 104
Signatures |  |  | 105

Table of Cont ents
DEFINITIONS
The following abbreviations or acronyms used in this report are defined below:

Abbreviation or Acronym | Definition | Abbreviation or Acronym | Definition
2021 Alliant Energy Proxy Statement | Alliant Energy’s Proxy Statement for the 2021 Annual Meeting of Shareowners | Fuel-related | Electric production fuel and purchased power
AEF | Alliant Energy Finance, LLC | GAAP | U.S. generally accepted accounting principles
AFUDC | Allowance for funds used during construction | GHG | Greenhouse gases
Alliant Energy | Alliant Energy Corporation | IPL | Interstate Power and Light Company
ARO | Asset retirement obligation | IRS | Internal Revenue Service
ATC | American Transmission Company LLC | ITC | ITC Midwest LLC
ATC Holdings | Interest in American Transmission Company LLC and ATC Holdco LLC | IUB | Iowa Utilities Board
ATI | AE Transco Investments, LLC | KWh | Kilowatt-hour
CA | Certificate of authority | Marshalltown | Marshalltown Generating Station
CAA | Clean Air Act | MDA | Management’s Discussion and Analysis of Financial Condition and Results of Operations
CCR | Coal combustion residuals | MGP | Manufactured gas plant
CO2 | Carbon dioxide | MISO | Midcontinent Independent System Operator, Inc.
Corporate Services | Alliant Energy Corporate Services, Inc. | MW | Megawatt
COVID-19 | Novel coronavirus | MWh | Megawatt-hour
CPCN | Certificate of Public Convenience and Necessity | N/A | Not applicable
CWIP | Construction work in progress | Note(s) | Combined Notes to Consolidated Financial Statements
DAEC | Duane Arnold Energy Center | OIP | Alliant Energy Omnibus Incentive Plan
DCP | Alliant Energy Deferred Compensation Plan | OPEB | Other postretirement benefits
DLIP | Alliant Energy Director Long Term Incentive Plan | PPA | Purchased power agreement
Dth | Dekatherm | PSCW | Public Service Commission of Wisconsin
EEP | Energy efficiency plan | Receivables Agreement | Receivables Purchase and Sale Agreement
EGU | Electric generating unit | Riverside | Riverside Energy Center
EPA | U.S. Environmental Protection Agency | SEC | Securities and Exchange Commission
EPS | Earnings per weighted average common share | U.S. | United States of America
Federal Tax Reform | Tax Cuts and Jobs Act | VEBA | Voluntary Employees’ Beneficiary Association
FERC | Federal Energy Regulatory Commission | VIE | Variable interest entity
Financial Statements | Consolidated Financial Statements | Whiting Petroleum | Whiting Petroleum Corporation
FTR | Financial transmission right | WPL | Wisconsin Power and Light Company

FORWARD-LOOKING STATEMENTS
Statements contained in this report that are not of historical fact are forward-looking statements intended to qualify for the safe harbors from liability established by the Private Securities Litigation Reform Act of 1995. These forward-looking statements can be identified as such because the statements include words such as “may,” “believe,” “expect,” “anticipate,” “plan,” “project,” “will,” “projections,” “estimate,” or other words of similar import. Similarly, statements that describe future financial performance or plans or strategies are forward-looking statements. Such forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements. Some, but not all, of the risks and uncertainties of Alliant Energy, IPL and WPL that could materially affect actual results include:
•the direct or indirect effects resulting from the COVID-19 pandemic on sales volumes, margins, operations, employees, contractors, vendors, the ability to complete construction projects, supply chains, customers’ inability to pay bills, suspension of disconnects, the market value of the assets that fund pension plans and the potential for additional funding requirements, the ability of counterparties to meet their obligations, compliance with regulatory requirements, the ability to implement regulatory plans, economic conditions and access to capital markets;
•the impact of penalties or third-party claims related to, or in connection with, a failure to maintain the security of personally identifiable information, including associated costs to notify affected persons and to mitigate their information security concerns;
•the direct or indirect effects resulting from terrorist incidents, including physical attacks and cyber attacks, or responses to such incidents;
•the impact of customer- and third party-owned generation, including alternative electric suppliers, in IPL’s and WPL’s service territories on system reliability, operating expenses and customers’ demand for electricity;
•the impact of energy efficiency, franchise retention and customer disconnects on sales volumes and margins;

| 1 |

Table of Cont ents
•the impact that price changes may have on IPL’s and WPL’s customers’ demand for electric, gas and steam services and their ability to pay their bills;
•IPL’s and WPL’s ability to obtain adequate and timely rate relief to allow for, among other things, the recovery of and/or the return on costs, including fuel costs, operating costs, transmission costs, deferred expenditures, deferred tax assets, tax expense, capital expenditures, and remaining costs related to EGUs that may be permanently closed and certain other retired assets, decreases in sales volumes, earning their authorized rates of return, and the payments to their parent of expected levels of dividends;
•federal and state regulatory or governmental actions, including the impact of legislation, and regulatory agency orders;
•the ability to utilize tax credits and net operating losses generated to date, and those that may be generated in the future, before they expire;
•the impacts of changes in tax rates, including adjustments made to deferred tax assets and liabilities;
•employee workforce factors, including changes in key executives, ability to hire and retain employees with specialized skills, ability to create desired corporate culture, collective bargaining agreements and negotiations, work stoppages or restructurings;
•any material post-closing payments related to any past asset divestitures, including the sale of Whiting Petroleum, which could result from, among other things, indemnification agreements, warranties, guarantees or litigation;
•weather effects on results of utility operations;
•issues associated with environmental remediation and environmental compliance, including compliance with all environmental and emissions permits, the CCR rule, future changes in environmental laws and regulations, including federal, state or local regulations for CO2 emissions reductions from new and existing fossil-fueled EGUs, and litigation associated with environmental requirements;
•increased pressure from customers, investors and other stakeholders to more rapidly reduce CO2 emissions;
•the ability to defend against environmental claims brought by state and federal agencies, such as the EPA, state natural resources agencies or third parties, such as the Sierra Club, and the impact on operating expenses of defending and resolving such claims;
•continued access to the capital markets on competitive terms and rates, and the actions of credit rating agencies;
•inflation and interest rates;
•the ability to complete construction of solar projects within the cost caps set by regulators and the ability to efficiently utilize the solar project tax benefits for the benefit of customers;
•changes in the price of delivered natural gas, transmission, purchased electricity and coal due to shifts in supply and demand caused by market conditions and regulations;
•disruptions in the supply and delivery of natural gas, purchased electricity and coal;
•the direct or indirect effects resulting from breakdown or failure of equipment in the operation of electric and gas distribution systems, such as mechanical problems and explosions or fires, and compliance with electric and gas transmission and distribution safety regulations, including regulations promulgated by the Pipeline and Hazardous Materials Safety Administration;
•issues related to the availability and operations of EGUs, including start-up risks, breakdown or failure of equipment, performance below expected or contracted levels of output or efficiency, operator error, employee safety, transmission constraints, compliance with mandatory reliability standards and risks related to recovery of resulting incremental costs through rates;
•impacts that excessive heat, excessive cold, storms or natural disasters may have on Alliant Energy’s, IPL’s and WPL’s operations and recovery of costs associated with restoration activities or on the operations of Alliant Energy’s investments;
•Alliant Energy’s ability to sustain its dividend payout ratio goal;
•changes to costs of providing benefits and related funding requirements of pension and OPEB plans due to the market value of the assets that fund the plans, economic conditions, financial market performance, interest rates, timing and form of benefits payments, life expectancies and demographics;
•material changes in employee-related benefit and compensation costs;
•risks associated with operation and ownership of non-utility holdings;
•changes in technology that alter the channels through which customers buy or utilize Alliant Energy’s, IPL’s or WPL’s products and services;
•impacts on equity income from unconsolidated investments from valuations and potential changes to ATC’s authorized return on equity;
•impacts of IPL’s future tax benefits from Iowa rate-making practices, including deductions for repairs expenditures, allocation of mixed service costs and state depreciation, and recoverability of the associated regulatory assets from customers, when the differences reverse in future periods;
•changes to the creditworthiness of counterparties with which Alliant Energy, IPL and WPL have contractual arrangements, including participants in the energy markets and fuel suppliers and transporters;
•current or future litigation, regulatory investigations, proceedings or inquiries;
•reputational damage from negative publicity, protests, fines, penalties and other negative consequences resulting in regulatory and/or legal actions;
•the effect of accounting standards issued periodically by standard-setting bodies;
•the ability to successfully complete tax audits and changes in tax accounting methods with no material impact on earnings and cash flows; and
•other factors listed in MDA and Item 1A Risk Factors.

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Alliant Energy, IPL and WPL each assume no obligation, and disclaim any duty, to update the forward-looking statements in this report, except as required by law.
WEBSITE ACCESS TO REPORTS
Alliant Energy, IPL and WPL make their periodic and current reports, and amendments to those reports, available, free of charge, on Alliant Energy’s website at www.alliantenergy.com/investors on the same day as such material is electronically filed with, or furnished to, the SEC. Alliant Energy, IPL and WPL are not including the information contained on Alliant Energy’s website as a part of, or incorporating it by reference into, this report.
PART I
This report includes information relating to Alliant Energy, IPL and WPL (as well as AEF and Corporate Services). Where appropriate, information relating to a specific entity has been segregated and labeled as such. Unless otherwise noted, the information herein excludes discontinued operations for all periods presented. The terms “we,” “our” and “us” used in this report refer collectively to Alliant Energy, IPL and WPL.
ITEM 1. BUSINESS
A. GENERAL
Alliant Energy maintains its principal executive offices in Madison, Wisconsin. Alliant Energy operates as a regulated investor-owned public utility holding company, and its purpose-driven strategy is to serve its customers and build strong communities. Alliant Energy’s primary focus is to provide regulated electric and natural gas service to approximately 975,000 electric and approximately 420,000 natural gas customers in the Midwest through its two public utility subsidiaries, IPL and WPL. The primary first tier wholly-owned subsidiaries of Alliant Energy are as follows:
1) IPL - is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa. IPL provides utility services to incorporated communities as directed by the IUB and utilizes non-exclusive franchises, which cover the use of public right-of-ways for utility facilities in incorporated communities for a maximum term of 25 years. At December 31, 2020, IPL supplied electric and natural gas service to approximately 495,000 and 225,000 retail customers, respectively, in Iowa. IPL also sells electricity to wholesale customers in Minnesota, Illinois and Iowa. IPL is also engaged in the generation and distribution of steam for two customers in Cedar Rapids, Iowa.
2) WPL - is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Wisconsin. WPL operates in municipalities pursuant to permits of indefinite duration and state statutes authorizing utility operation in areas annexed by a municipality. At December 31, 2020, WPL supplied electric and natural gas service to approximately 480,000 and 195,000 retail customers, respectively. WPL also sells electricity to wholesale customers in Wisconsin.
3) CORPORATE SERVICES - provides administrative services to Alliant Energy, IPL, WPL and AEF.
4) AEF - Alliant Energy’s non-utility holdings are organized under AEF, which manages a portfolio of wholly-owned subsidiaries and additional holdings, including the following distinct platforms:
ATI - currently holds all of Alliant Energy’s interest in ATC Holdings. ATC Holdings is comprised of a 16% ownership interest in ATC and a 20% ownership interest in ATC Holdco LLC. ATC is an independent, for-profit, transmission-only company. ATC Holdco LLC holds Duke-American Transmission Company, LLC, a joint venture between Duke Energy Corporation and ATC, that owns electric transmission infrastructure in North America.
Non-utility Wind Farm - includes a 50% cash equity ownership interest in a 225 MW non-utility wind farm located in Oklahoma.
Sheboygan Falls Energy Facility - is a 347 MW, simple-cycle, natural gas-fired EGU near Sheboygan Falls, Wisconsin, which is leased to WPL for an initial period of 20 years ending in 2025.
Travero - formerly known as Transportation, Travero owns and operates a short-line rail freight service in Iowa; a barge, rail and truck freight terminal on the Mississippi River; freight brokerage and logistics management services; and a rail-served warehouse in Alliant Energy’s Big Cedar Industrial Center Mega-site in Cedar Rapids, Iowa, which is currently scheduled to open later in 2021.

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B. INFORMATION RELATING TO ALLIANT ENERGY ON A CONSOLIDATED BASIS
1) HUMAN CAPITAL MANAGEMENT - Our purpose to serve customers and build strong communities, as well as our values, are the foundation of our culture, guide our actions, and describe how we accomplish our strategy. We work to attract, retain, reward and develop a diverse and qualified workforce of high-performing employees and teams because our employees and culture are critical to our strategy.
Employees - At December 31, 2020, Alliant Energy, IPL and WPL had the following full- and part-time employees:

| Total |  | Number of |  | Percentage of Employees
| Number of |  | Bargaining Unit |  | Covered by Collective
| Employees |  | Employees |  | Bargaining Agreements
Alliant Energy | 3,375 |  | 1,792 |  |  | 53%
IPL | 1,176 |  | 804 |  |  | 68%
WPL | 1,072 |  | 879 |  |  | 82%

The majority of IPL’s bargaining unit employees are covered by the International Brotherhood of Electrical Workers Local 204 (Cedar Rapids) collective bargaining agreement, which expires on August 31, 2024. All of WPL’s bargaining unit employees are covered by the International Brotherhood of Electrical Workers Local 965 collective bargaining agreement, which expires on May 31, 2022.
Safety - Safety is integral to our company’s culture. It is one of our Values – “Live safety. Everyone. Always. Our first priority is that nobody gets hurt.” Alliant Energy is committed to providing a safe environment for our employees, visitors, customers, contractors, vendors and the communities in which we live and work.
We focus on the proactive management of our safety performance. Our comprehensive program includes leading indicators such as tracking and reporting near misses and unsafe conditions, which we believe helps prevent similar incidents from occurring elsewhere. We also conduct internal safety assessments of our generating facilities.
We maintain executive and local safety leadership teams to establish our safety vision, strategy and priorities, as well as ensure education and recognition of employee actions that improve our safety culture. This leadership provides strong support for sustained growth of both employee and public safety programs and initiatives.
Public safety is equally important as we interact with our customers to provide energy to their homes and businesses. We offer awareness campaigns, natural gas and electric public safety presentations, and free online resources and training programs and guidance to assist local emergency responders.
Total Rewards - Our market-competitive Total Rewards programs are designed to meet the varied and evolving needs of our employees and their families. Through a variety of flexible health and wellness programs, we offer employees choice, support their financial, physical, and mental well-being, provide tools and resources to help improve or maintain their health status, and promote engagement in healthy behaviors.
In addition to competitive salaries and wages, our Total Rewards programs include:
•a 401(k) savings plan with an employer match;
•healthcare and insurance benefits, including medical, vision, dental, life, short-term disability, and long-term disability insurance;
•health savings and flexible spending accounts;
•paid time off to use for vacation, personal time, sick time, holidays, bereavement, jury duty, military leave, parental leave, maternity leave, and adoption leave;
•family care resources;
•adoption assistance;
•legal planning assistance;
•Employee Assistance Program;
•tuition reimbursement;
•Vacation Donation Program; and
•Volunteer Grants & Matching Gifts Program.
Diversity, Equity and Inclusion (DE&I) - A diverse, equitable and inclusive workplace is crucial for the success and retention of our employees, to attract future talent and to execute our purpose-driven strategy to serve our customers and build strong communities. It is one of our Values – “Care for others: Together we create a workplace where people feel like they belong and can use their unique backgrounds, talents and perspectives to their fullest potential.”
Our efforts to create a diverse and inclusive workforce include:
•learning opportunities for employees, such as inviting employees to participate in area diversity summits and supporting company-wide listening sessions, speakers and programs;

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•Employee Resource Groups that foster a diverse and inclusive workplace that supports employee well-being while promoting professional development and enhancing community relationships; and
•a DE&I Leadership Team that partners with the Human Resources recruiting department and hiring managers to attract more diverse applicants.
Our DE&I initiatives also include a focus on building a diverse Board of Directors. We believe it is in our shareowners’ best interest to have a diverse Board representing a wide breadth of experiences and perspectives. Our Board currently has approximately 33% gender diversity and 22% ethnic diversity.
Our 2020 DE&I accomplishments include:
•received a perfect score on the Corporate Equality Index administered by the Human Rights Campaign Foundation to benchmark LGBTQ+ rights, policies and practices;
•held a Day of Understanding where executives met with employees and held conversations about unconscious bias; and
•selected for the 2020 Bloomberg Gender-Equality Index.
Alliant Energy’s short-term incentive compensation plan includes diversity metrics to drive leadership accountability for efforts to advance a diverse and inclusive culture.
Talent Development and Workforce Readiness - We support employees in the growth of their careers through several training opportunities and development programs. These include tuition reimbursement, online, instructor-led and on-the-job learning formats, as well as leadership development and succession planning.
In addition, we have an apprenticeship program that combines supervised, structured on-the-job training with related instruction to produce highly skilled trade and technical workers. Our program builds lifetime skills and comprehensive knowledge in the high-demand technical trades necessary for our success. The program gives us the flexibility to tailor training to match our needs – training employees in our facilities, on our equipment, and consistent with our safety standards and employee expectations. We instill company Values, methods and procedures from day one.
2) REGULATION - Alliant Energy, IPL and WPL are subject to regulation by various federal, state and local agencies. The following includes the primary regulations impacting Alliant Energy’s, IPL’s and WPL’s businesses.
FERC -
Public Utility Holding Company Act of 2005 - Alliant Energy is registered with FERC as a public utility holding company, pursuant to the Public Utility Holding Company Act of 2005, and is required to maintain certain records and to report certain transactions involving its public utilities, service company and other entities regulated by FERC. Corporate Services, IPL and WPL are subject to regulation by FERC under the Public Utility Holding Company Act of 2005 for various matters including, but not limited to, affiliate transactions, public utility mergers, acquisitions and dispositions, and books, records and accounting requirements.
Energy Policy Act - The Energy Policy Act requires creation of an Electric Reliability Organization to provide oversight by FERC. FERC designated North American Electric Reliability Corporation as the overarching Electric Reliability Organization. Midwest Reliability Organization, which is a regional member of North American Electric Reliability Corporation, has direct responsibility for mandatory electric reliability standards for IPL and WPL.
Federal Power Act - FERC also has jurisdiction, under the Federal Power Act, over certain electric utility facilities and operations, electric wholesale and transmission rates, dividend payments, issuance of IPL’s securities, and accounting practices of Corporate Services, IPL and WPL.
Electric Wholesale Rates - IPL and WPL receive wholesale electric market-based rate authority from FERC. Market-based rate authorization allows for wholesale sales of electricity within the MISO market and in transactions directly with third parties, based on the market value of the transactions. IPL and WPL also have FERC-approved cost of service formula-based rates related to the provision of firm full- and partial-requirement wholesale electric sales, which allow for true-ups to actual costs, including fuel costs.
Electric Transmission Rates - FERC regulates the rates charged for electric transmission facilities used in interstate commerce. IPL and WPL do not own or operate electric transmission facilities; however, both IPL and WPL pay for the use of the interstate electric transmission system based upon FERC-regulated rates. IPL and WPL rely primarily on the use of the ITC and ATC transmission systems, respectively.
Natural Gas Act - FERC regulates the transportation and sale for resale of natural gas in interstate commerce under the Natural Gas Act. Under the Natural Gas Act, FERC has authority over certain natural gas facilities and operations of IPL and WPL.

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IUB - IPL is subject to regulation by the IUB for various matters including, but not limited to, retail utility rates and standards of service, accounting requirements, sales of assets with values that exceed 3% of IPL’s revenues, and approval of the location and construction of EGUs.
Retail Utility Base Rates - IPL files periodic requests with the IUB for retail rate changes and may base those requests on either historical or forward-looking test periods. The IUB must decide on requests for retail rate changes within 10 months of the date of the application for which changes are filed. The historical test periods may be adjusted for certain known and measurable changes to capital investments, cost of capital and operating and maintenance expenses consistent with IUB rules and regulations. Forward-looking test periods must follow established regulatory principles as applied to the forecasted information and include a requirement for a subsequent proceeding review after the close of the forward-looking test period to evaluate whether actual costs and revenue were reasonably consistent with the forward-looking test period.
Energy Efficiency - In accordance with Iowa law, IPL is required to file an EEP every five years with the IUB. An EEP provides a utility’s plan and related budget to achieve specified levels of electric and gas energy savings. IUB approval demonstrates that IPL’s EEP is reasonably expected to achieve cost-effective delivery of the energy efficiency programs. Refer to Note 1(g) for discussion of the recovery of these costs from IPL’s retail electric and gas customers.
Electric Generating Units - IPL must obtain a certificate of public convenience, use and necessity (GCU Certificate) from the IUB in order to construct a new, or significantly alter (including fuel switching) an existing, EGU located in Iowa with 25 MW or more of capacity. IPL’s ownership and operation of EGUs (including those located outside the state of Iowa) to serve Iowa customers is subject to retail utility rate regulation by the IUB.
Gas Pipeline Projects - IPL must obtain a pipeline permit from the IUB related to the siting of utility gas pipelines in Iowa that will be operated at a pressure over 150 pounds per square inch and will transport gas to a distribution system or single, large volume customer.
Advance Rate-making Principles - Iowa law provides Iowa utilities with rate-making principles prior to making certain generation investments in Iowa. As a result, IPL may file for, and the IUB must render a decision on, rate-making principles for certain new EGUs located in Iowa, including any alternative energy production facility (such as a wind or solar facility), combined-cycle natural gas-fired EGU, and certain base-load EGUs with a nameplate generating capacity of 300 MW or more (such as nuclear or coal-fired generation). Advance rate-making principles are also available for the repowering of an alternative energy production facility or certain significant alterations of an existing EGU. Upon approval of rate-making principles by the IUB, IPL must either build the EGU or repower the alternative energy production facility under the approved rate-making principles, or not at all.
Electric Generating Unit Environmental Controls Projects - IPL is required to submit an updated emissions plan and budget biennially to the IUB setting out a multi-year plan and budget for managing regulated emissions from its coal-fired EGUs in a cost-effective manner. IPL must simultaneously submit this plan and budget to the Iowa Department of Natural Resources for a determination of whether the plan and budget meet state environmental requirements for regulated emissions. The reasonable and prudent costs associated with implementing the approved plan are expected to be included in IPL’s future retail electric rates.
PSCW - WPL is subject to regulation by the PSCW related to its operations in Wisconsin for various matters including, but not limited to, retail utility rates and standards of service, accounting requirements, issuance and use of proceeds of securities, affiliate transactions, approval of the location and construction of EGUs and certain other additions and extensions to facilities. In addition, Alliant Energy is subject to regulation by the PSCW for the type and amount of Alliant Energy’s holdings in non-utility businesses and other affiliated interest activities, among other matters.
Retail Utility Base Rates - WPL files periodic requests with the PSCW for retail rate changes. These filings are required to be based on forward-looking test periods. There is no statutory time limit for the PSCW to decide on retail base rate requests. However, the PSCW attempts to process retail base rate reviews in approximately 10 months and has the ability to approve interim retail rate relief, subject to refund, if necessary. Currently, WPL is required to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels.
Public Benefits - WPL contributes 1.2% of its annual retail utility revenues to help fund Focus on Energy, Wisconsin’s state-wide energy efficiency and renewable energy resource program. In addition, WPL contributes to a program that provides assistance to income-eligible residents in Wisconsin. These contributions are recovered from customers through a bill surcharge of up to 3% of customers’ utilities bills. Refer to Note 1(g) for discussion of the recovery of these costs from WPL’s retail electric and gas customers.
New Electric Generating Units - A CA application is required to be filed with the PSCW for construction approval of any new EGU with a capacity of less than 100 MW and a project cost of $11.0 million or more. WPL must obtain a CPCN from the PSCW in order to construct a new EGU in Wisconsin with a capacity of 100 MW or more. In addition, WPL’s ownership and operation of EGUs (including those located outside the state of Wisconsin) to serve Wisconsin customers are subject to retail utility rate regulation by the PSCW.

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Electric Generating Unit Upgrades and Electric Distribution Projects - A CA application is required to be filed with the PSCW for construction approval of any additions to EGUs, including environmental controls projects, as well as electric distribution projects, with estimated project costs of $11.0 million or more.
Gas Distribution Projects - A CA application is required to be filed with the PSCW for construction approval of gas projects with an estimated project cost of $2.5 million or more and at any time that WPL requests to extend gas service to a new portion of its service territory.
Advance Rate-making Principles - Wisconsin law provides Wisconsin utilities with the opportunity to request rate-making principles prior to the purchase or construction of any EGU utilized to serve Wisconsin customers. WPL is not obligated to file for or accept authorized rate-making principles under Wisconsin law. WPL can proceed with an approved project under traditional rate-making terms or accept authorized rate-making principles under Wisconsin law.
Environmental - Alliant Energy, IPL and WPL are subject to regulation of environmental matters by federal, state and local authorities as a result of their current and past operations. Alliant Energy, IPL and WPL monitor these environmental matters and address them by installing controls that reduce emissions and by implementing operational modifications or other measures to address compliance obligations. There is currently significant regulatory uncertainty with respect to environmental rules and regulations discussed below. Given the dynamic nature of environmental regulations and other related regulatory requirements, Alliant Energy, IPL and WPL have compliance plans to address these environmental obligations. Prudent expenditures incurred by IPL and WPL to comply with environmental requirements are eligible to be recovered in rates from their customers. The following are major environmental matters that could potentially have a significant impact on financial condition and results of operations.
Climate Change and Greenhouse Gases Regulations - There is continued deliberation on the public policy that the U.S. should adopt to address climate change, including assessment of both domestic actions and international efforts. In 2007, the Supreme Court provided direction on the EPA’s authority to regulate GHG and ruled that these emissions are covered by the CAA. In 2009, the EPA issued a ruling that found GHG emissions contribute to climate change, and therefore, threaten public health and welfare, which was the prerequisite for implementing carbon reduction standards under the CAA. While the EPA’s rules to regulate GHG issued under the authority of the CAA remain subject to further review, growing emphasis on climate change and evolving energy technologies are driving efforts to decarbonize the environment through voluntary emissions reductions. The primary GHG directly emitted from Alliant Energy’s utility operations is CO2 from the combustion of fossil fuels at their larger EGUs.
Clean Air Act Section 111(d) - In 2015, the EPA published final standards under Section 111(d) of the CAA, referred to as the Clean Power Plan, to reduce CO2 emissions from existing fossil-fueled EGUs. In July 2019, the EPA published the final Affordable Clean Energy rule, which repealed the Clean Power Plan effective September 6, 2019. The Affordable Clean Energy rule established emission guidelines for states to develop plans by July 2022 to reduce CO2 emissions from existing coal-fired EGUs. In January 2021, the U.S. Court of Appeals for the District of Columbia Circuit vacated the Affordable Clean Energy rule and remanded the rule back to the EPA for reconsideration. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters.
Clean Air Act Section 111(b) - In 2015, the EPA published final standards under Section 111(b) of the CAA, which establish CO2 emissions limits for certain new fossil-fueled EGUs. Marshalltown and West Riverside are subject to the EPA’s Section 111(b) regulation and have been designed to achieve compliance with these standards. Litigation related to Section 111(b) is suspended while the EPA revises Section 111(b), and Alliant Energy, IPL and WPL are currently unable to predict with certainty the impact of these standards. In January 2021, the EPA published a final rule establishing that EGUs are a significant source of GHG and reaffirming that CO2 emissions from EGUs can be regulated under Section 111 of the CAA.
Water Quality -
Effluent Limitation Guidelines - In 2015, the EPA published final effluent limitation guidelines, which required changes to discharge limits for wastewater from certain IPL and WPL steam EGUs. In December 2020, revised effluent limitation guidelines became effective, which incorporated flexibility to the 2015 rule, including a new subcategory for coal-fired EGUs that will be retired or converted to no longer burn coal before 2028. Compliance for existing steam-electric generating facilities is determined by each facility’s wastewater discharge permit and will generally be required by December 31, 2025. Projects required for compliance are facility-specific. Estimated capital expenditures to comply with the December 2020 guidelines for 2021 through 2024 are included in the “Other Generation” line in the construction and acquisition expenditures table in “Liquidity and Capital Resources” in MDA. In January 2021, the new Presidential Administration issued an Executive Order requiring the review and possible revision of environmental regulations issued during the prior Administration. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of the January 2021 Executive Order.
Land and Solid Waste -
Coal Combustion Residuals Rule - The final CCR Rule, which regulates CCR as a non-hazardous waste, became effective in 2015. IPL and WPL have coal-fired EGUs with coal ash ponds and active CCR landfills that are impacted by this rule.

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Litigation related to the CCR Rule remains on-going and has resulted in various proposed rule updates. Alliant Energy, IPL and WPL are currently unable to predict with certainty the impact of these updates.
MGP Sites - Refer to Note 17(e) for discussion of IPL’s and WPL’s MGP sites.
Renewable Energy Standards - Iowa and Wisconsin have renewable energy standards, which establish the minimum amount of energy IPL and WPL must supply from renewable resources. IPL primarily relies upon renewable energy generated from the wind resources it owns and renewable energy acquired under PPAs to meet these requirements. WPL utilizes its current renewable portfolio, which primarily consists of wind and hydro energy, both owned and acquired under PPAs, to meet these requirements. IPL and WPL currently exceed their respective renewable energy standards requirements.
3) STRATEGY - Refer to “Overview” in MDA for discussion of Alliant Energy’s strategy, which supports its mission to deliver energy solutions and exceptional service that its customers and communities count on - safely, efficiently and responsibly.
C. INFORMATION RELATING TO UTILITY OPERATIONS
Alliant Energy’s utility business (IPL and WPL) has three segments: a) electric operations; b) gas operations; and c) other, which includes IPL’s steam operations and the unallocated portions of the utility business. IPL’s and WPL’s electric, gas and other revenues as a percentage of total revenues were as follows:

IPL |  | WPL

1) ELECTRIC UTILITY OPERATIONS
General - Electric utility operations represent the largest operating segment for Alliant Energy, IPL and WPL. Alliant Energy’s electric utility operations are located in the Midwest with IPL providing retail electric service in Iowa and WPL providing retail and wholesale electric service in Wisconsin. IPL also sells electricity to wholesale customers in Minnesota, Illinois and Iowa. Refer to the “Electric Operating Information” tables for additional details regarding electric utility operations.
Customers - IPL and WPL provide electric utility service to a diversified base of retail customers in several industries, with the largest concentrations in the farming, agriculture, industrial manufacturing, chemical (including ethanol), packaging and food industries. IPL and WPL also sell electricity to wholesale customers, which primarily consist of municipalities and rural electric cooperatives.
Seasonality - Electric sales are seasonal to some extent with the annual peak normally occurring in the summer months due to air conditioning requirements. Electric sales are also impacted to a certain extent in the winter months due to heating requirements.
Competition - Retail electric customers in Iowa and Wisconsin currently do not have the ability to choose their electric supplier, and IPL and WPL have obligations to serve all their retail electric customers. Although electric service in Iowa and Wisconsin is regulated, IPL and WPL still face competition from self-generation by large industrial customers, customer- and third party-owned generation (e.g. solar panels), alternative energy sources, and petitions to municipalize (Iowa) as well as service territory expansions by municipal utilities through annexations (Wisconsin). In addition, the wholesale power market is competitive and IPL and WPL compete against independent power producers, other utilities and MISO market purchases to serve wholesale customers for their electric energy and capacity needs. Alliant Energy’s strategy includes actions to retain current customers and attract new customers into IPL’s and WPL’s service territories in an effort to keep energy rates low for all of their customers. Refer to “Overview” in MDA for discussion of the strategy element focusing on growing customer demand.
Electric Supply - Alliant Energy, IPL and WPL have met, and expect to continue meeting, customer demand of electricity through a mix of electric supply, including owned EGUs, PPAs and additional purchases from wholesale energy markets. Alliant Energy expects its mix of electric supply to change in the next several years with IPL’s and WPL’s planned solar generation and the proposed retirement and/or fuel switching of various EGUs, as well as the potential sale of partial interests in West Riverside to neighboring utilities. Long-term generation plans are intended to meet customer demand, reduce air emissions and water impacts, reduce reliance on wholesale market purchases and mitigate the impacts of future EGU

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retirements while maintaining compliance with long-term electric demand planning reserve margins, renewable energy standards established by regulators and other various requirements.
Electric Demand Planning Reserve Margin - IPL and WPL are required to maintain a planning reserve margin above their load at the time of the MISO-wide peak to ensure reliability of electric service to their customers. The required installed capacity reserve margin is 18.3% and the required unforced capacity reserve margin is 9.4% for the June 1, 2021 through May 31, 2022 MISO planning year. IPL and WPL currently have adequate capacity to meet such MISO planning reserve margin requirements.
Generation Fuel Supply - IPL and WPL own a portfolio of EGUs located in Iowa, Wisconsin and Minnesota with a diversified fuel mix that includes natural gas, renewable resources and coal. Refer to “Properties” in Item 2 for details of IPL’s and WPL’s EGUs. The average cost of delivered fuel per million British Thermal Units used for electric generation was as follows:

| IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
All fuels | $2.22 |  |  | $2.17 |  |  | $2.46 |  |  | $2.36 |  |  | $2.55 |  |  | $2.72 |
Natural gas (a) | 2.54 |  |  | 2.52 |  |  | 3.12 |  |  | 2.51 |  |  | 2.76 |  |  | 3.30 |
Coal | 1.84 |  |  | 1.81 |  |  | 1.97 |  |  | 2.19 |  |  | 2.35 |  |  | 2.45 |

(a)The average cost of natural gas includes commodity and transportation costs, as well as realized gains and losses from swap and option contracts used to hedge the price of natural gas volumes expected to be used by IPL’s and WPL’s natural gas-fired EGUs.
Natural Gas - Alliant Energy, IPL and WPL own several natural gas-fired EGUs, and WPL also has exclusive rights to the output of AEF’s Sheboygan Falls Energy Facility under an affiliated lease agreement. These facilities help meet customer demand for electricity when natural gas prices are low enough to make natural gas-fired generation economical compared to other fuel sources. Alliant Energy manages the gas supply to these gas-fired EGUs and helps ensure an adequate supply is available at known prices through a combination of gas commodity, pipeline transportation and storage agreements held by IPL and WPL for numerous years. Alliant Energy, IPL and WPL believe they are reasonably insulated against gas price volatility for these EGUs given their use of forward contracts and hedging practices, as well as their regulatory cost-recovery mechanisms.
Coal - Coal is one of the fuel sources for owned EGUs. Coal contracts entered into with different entities help ensure that a specified supply of coal is available, and delivered, at known prices for IPL’s and WPL’s coal-fired EGUs. Alliant Energy, IPL and WPL believe their coal supply portfolio represents a reasonable balance between the risks of insufficient supplies and those associated with being unable to respond to future coal market changes. Remaining coal requirements are expected to be met from either future term contracts or purchases in the spot market. Currently, all of the coal utilized by IPL and WPL is from the Wyoming Powder River Basin.
Alliant Energy, IPL and WPL believe they are reasonably insulated against coal price volatility given their current coal procurement process, the specific coal market in their primary purchase region and regulatory cost-recovery mechanisms. The coal procurement process supports periodic purchases, staggering of contract terms, stair-stepped levels of supply going forward and supplier diversity. Similarly, given the term lengths of their transportation agreements and strategic alignment of agreement expirations for negotiation purposes, Alliant Energy, IPL and WPL believe they are reasonably insulated against future higher coal transportation rates from the major railroads.
Purchased Power - IPL and WPL periodically enter into PPAs and purchase electricity from wholesale energy markets to meet a portion of their customer demand for electricity.
Electric Transmission - IPL and WPL do not own electric transmission service assets and currently receive transmission services from ITC and ATC, respectively. ITC and ATC are independent, for-profit, transmission-only companies and are transmission-owning members of the MISO Regional Transmission Organization, Midwest Reliability Organization and Reliability First Corporation Regional Entities. The annual transmission service rates that ITC or ATC charges their customers are calculated each calendar year using a FERC-approved cost of service formula rate. As a result, ITC and ATC can implement new rates each calendar year without filing a request with FERC. However, new rates are subject to challenge by either FERC or customers. If the rates proposed by ITC or ATC are determined by FERC to be unjust or unreasonable, or another mechanism is determined by FERC to be just and reasonable, ITC’s or ATC’s rates would change accordingly. Refer to Note 1(g) for discussion of a transmission cost rider utilized by IPL for recovery of its electric transmission service expense, and discussion of WPL’s electric transmission service expense, which is recovered from its retail electric customers through changes in base rates determined during periodic rate proceedings. Refer to Note 17(g) for discussion of MISO transmission owner return on equity complaints.

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MISO Markets - IPL and WPL are members of MISO, a FERC-approved Regional Transmission Organization, which is responsible for monitoring and ensuring equal access to the transmission system in their footprint. IPL and WPL participate in the wholesale energy and ancillary services markets operated by MISO, which are discussed in more detail below. As agent for IPL and WPL, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases between IPL and WPL based on statements received from MISO.
Wholesale Energy Market - IPL and WPL sell and purchase power in the day-ahead and real-time wholesale energy markets operated by MISO. MISO’s bid/offer-based markets compare the cost of IPL and WPL generation against other generators, which affects IPL and WPL generation operations, energy purchases and energy sales. MISO generally dispatches the lowest cost generators, while recognizing current system constraints, to reduce costs for purchasers in the wholesale energy market. In addition, MISO may dispatch generators that support reliability needs, but that would not have operated based on economic needs. In these cases, MISO’s settlement assures that these generators are made whole financially for their variable costs.
Ancillary Services Market - IPL and WPL also participate in MISO’s ancillary services market, which integrates the procurement and use of regulation and contingency reserves with the existing wholesale energy market to ensure reliability of electricity supply. MISO’s ancillary services market has had the overall impact of lowering ancillary services costs in the MISO footprint.
Financial Transmission Rights and Auction Revenue Rights - In areas of constrained transmission capacity, energy costs could be higher due to congestion and its impact on locational marginal prices. FTRs provide a hedge for certain congestion costs that occur in the MISO energy market. MISO allocates auction revenue rights to IPL and WPL annually based on a fiscal year from June 1 through May 31 and historical use of the transmission system. The allocated auction revenue rights are used by IPL and WPL to acquire FTRs through the FTR auctions operated by MISO.
Resource Adequacy - MISO has resource adequacy requirements to help ensure adequate resources to meet forecasted peak load obligations plus a reserve margin. Only accredited capacity assigned to EGUs is available to meet these requirements. In order for an EGU to receive accredited capacity, it must meet MISO capacity accreditation requirements, which can include satisfying transmission requirements identified in its interconnection agreement prior to the MISO planning year.

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Electric Operating Information - Alliant Energy | 2020 |  | 2019 |  | 2018
Revenues (in millions): |  |  |  |  |
Residential | $1,093 |  |  | $1,092 |  |  | $1,063 |
Commercial | 718 |  |  | 770 |  |  | 736 |
Industrial | 841 |  |  | 889 |  |  | 889 |
Retail subtotal | 2,652 |  |  | 2,751 |  |  | 2,688 |
Sales for resale | 204 |  |  | 250 |  |  | 259 |
Other | 64 |  |  | 63 |  |  | 53 |
Total | $2,920 |  |  | $3,064 |  |  | $3,000 |
Sales (000s MWh): |  |  |  |  |
Residential | 7,294 |  |  | 7,207 |  |  | 7,367 |
Commercial | 6,107 |  |  | 6,466 |  |  | 6,487 |
Industrial | 11,134 |  |  | 11,448 |  |  | 11,830 |
Retail subtotal | 24,535 |  |  | 25,121 |  |  | 25,684 |
Sales for resale | 6,046 |  |  | 6,594 |  |  | 5,804 |
Other | 71 |  |  | 79 |  |  | 96 |
Total | 30,652 |  |  | 31,794 |  |  | 31,584 |
Customers (End of Period): |  |  |  |  |
Retail | 974,144 |  |  | 968,485 |  |  | 962,654 |
Other | 2,841 |  |  | 2,816 |  |  | 2,860 |
Total | 976,985 |  |  | 971,301 |  |  | 965,514 |
Other Selected Electric Data: |  |  |  |  |
Maximum summer peak hour demand (MW) | 5,496 |  |  | 5,626 |  |  | 5,459 |
Maximum winter peak hour demand (MW) | 4,158 |  |  | 4,395 |  |  | 4,556 |
Cooling degree days (a): |  |  |  |  |
Cedar Rapids, Iowa (IPL) (normal - 800) | 800 |  |  | 805 |  |  | 1,032 |
Madison, Wisconsin (WPL) (normal - 686) | 736 |  |  | 657 |  |  | 799 |
Sources of electric energy (000s MWh): |  |  |  |  |
Gas | 10,440 |  |  | 11,060 |  |  | 9,731 |
Purchased power: |  |  |  |  |
Nuclear | 2,347 |  |  | 3,748 |  |  | 3,538 |
Wind (b) | 3,683 |  |  | 2,383 |  |  | 1,086 |
Other (b) | 2,521 |  |  | 3,264 |  |  | 4,076 |
Wind (b) | 4,872 |  |  | 2,896 |  |  | 1,603 |
Coal | 7,021 |  |  | 8,643 |  |  | 12,113 |
Other (b) | 254 |  |  | 239 |  |  | 240 |
Total | 31,138 |  |  | 32,233 |  |  | 32,387 |
Revenue per KWh sold to retail customers (cents) | 10.81 |  |  | 10.95 |  |  | 10.47 |

(a)Cooling degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base. Normal degree days are calculated using a rolling 20-year average of historical cooling degree days. Refer to “Gas Operating Information” below for details of heating degree days.
(b)All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with renewable energy standards or other regulatory requirements.

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Electric Operating Information | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Revenues (in millions): |  |  |  |  |  |  |  |  |  |  |
Residential | $602 |  |  | $601 |  |  | $590 |  |  | $491 |  |  | $491 |  |  | $473 |
Commercial | 474 |  |  | 510 |  |  | 487 |  |  | 244 |  |  | 260 |  |  | 249 |
Industrial | 488 |  |  | 504 |  |  | 501 |  |  | 353 |  |  | 385 |  |  | 388 |
Retail subtotal | 1,564 |  |  | 1,615 |  |  | 1,578 |  |  | 1,088 |  |  | 1,136 |  |  | 1,110 |
Sales for resale | 88 |  |  | 128 |  |  | 117 |  |  | 116 |  |  | 122 |  |  | 142 |
Other | 43 |  |  | 38 |  |  | 36 |  |  | 21 |  |  | 25 |  |  | 17 |
Total | $1,695 |  |  | $1,781 |  |  | $1,731 |  |  | $1,225 |  |  | $1,283 |  |  | $1,269 |
Sales (000s MWh): |  |  |  |  |  |  |  |  |  |  |
Residential | 3,623 |  |  | 3,613 |  |  | 3,752 |  |  | 3,671 |  |  | 3,594 |  |  | 3,615 |
Commercial | 3,835 |  |  | 4,109 |  |  | 4,169 |  |  | 2,272 |  |  | 2,357 |  |  | 2,318 |
Industrial | 6,372 |  |  | 6,420 |  |  | 6,749 |  |  | 4,762 |  |  | 5,028 |  |  | 5,081 |
Retail subtotal | 13,830 |  |  | 14,142 |  |  | 14,670 |  |  | 10,705 |  |  | 10,979 |  |  | 11,014 |
Sales for resale | 3,485 |  |  | 4,479 |  |  | 2,980 |  |  | 2,561 |  |  | 2,115 |  |  | 2,824 |
Other | 34 |  |  | 36 |  |  | 37 |  |  | 37 |  |  | 43 |  |  | 59 |
Total | 17,349 |  |  | 18,657 |  |  | 17,687 |  |  | 13,303 |  |  | 13,137 |  |  | 13,897 |
Customers (End of Period): |  |  |  |  |  |  |  |  |  |  |
Retail | 494,258 |  |  | 492,830 |  |  | 489,831 |  |  | 479,886 |  |  | 475,655 |  |  | 472,823 |
Other | 856 |  |  | 855 |  |  | 900 |  |  | 1,985 |  |  | 1,961 |  |  | 1,960 |
Total | 495,114 |  |  | 493,685 |  |  | 490,731 |  |  | 481,871 |  |  | 477,616 |  |  | 474,783 |
Other Selected Electric Data: |  |  |  |  |  |  |  |  |  |  |
Maximum summer peak hour demand (MW) | 2,951 |  |  | 2,944 |  |  | 2,929 |  |  | 2,609 |  |  | 2,682 |  |  | 2,647 |
Maximum winter peak hour demand (MW) | 2,311 |  |  | 2,377 |  |  | 2,553 |  |  | 1,873 |  |  | 2,031 |  |  | 2,011 |
Cooling degree days (a): |  |  |  |  |  |  |  |  |  |  |
Cedar Rapids, Iowa (IPL) (normal - 800) | 800 |  |  | 805 |  |  | 1,032 |  |  | N/A |  | N/A |  | N/A
Madison, Wisconsin (WPL) (normal - 686) | N/A |  | N/A |  | N/A |  | 736 |  |  | 657 |  |  | 799 |
Sources of electric energy (000s MWh): |  |  |  |  |  |  |  |  |  |  |
Gas | 5,296 |  |  | 6,362 |  |  | 5,930 |  |  | 5,144 |  |  | 4,698 |  |  | 3,801 |
Purchased power: |  |  |  |  |  |  |  |  |  |  |
Nuclear | 2,347 |  |  | 3,748 |  |  | 3,538 |  |  | N/A |  | N/A |  | N/A
Wind (b) | 2,359 |  |  | 1,788 |  |  | 549 |  |  | 1,324 |  |  | 595 |  |  | 537 |
Other (b) | 391 |  |  | 326 |  |  | 1,472 |  |  | 2,130 |  |  | 2,938 |  |  | 2,604 |
Wind (b) | 3,843 |  |  | 2,067 |  |  | 890 |  |  | 1,029 |  |  | 829 |  |  | 713 |
Coal | 3,185 |  |  | 4,470 |  |  | 5,690 |  |  | 3,836 |  |  | 4,173 |  |  | 6,423 |
Other (b) | 12 |  |  | 11 |  |  | 40 |  |  | 242 |  |  | 228 |  |  | 200 |
Total | 17,433 |  |  | 18,772 |  |  | 18,109 |  |  | 13,705 |  |  | 13,461 |  |  | 14,278 |
Revenue per KWh sold to retail customers (cents) | 11.31 |  |  | 11.42 |  |  | 10.76 |  |  | 10.16 |  |  | 10.35 |  |  | 10.08 |

(a)Cooling degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base. Normal degree days are calculated using a rolling 20-year average of historical cooling degree days. Refer to “Gas Operating Information” below for details of heating degree days.
(b)All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with renewable energy standards or other regulatory requirements.
2) GAS UTILITY OPERATIONS
General - Gas utility operations represent the second largest operating segment for Alliant Energy, IPL and WPL. Alliant Energy’s gas utility operations are located in the Midwest with IPL providing gas service in Iowa and WPL providing gas service in Wisconsin. Refer to the “Gas Operating Information” tables for additional details regarding gas utility operations. Refer to Note 1(g) for information relating to utility natural gas cost recovery mechanisms and Note 17(b) for discussion of natural gas commitments.
Customers - IPL and WPL provide gas utility service to a diversified base of retail customers and industries, including research, education, hospitality, manufacturing and chemicals (including ethanol). In addition, IPL and WPL provide transportation service to commercial and industrial customers by moving customer-owned gas through Alliant Energy’s distribution systems to the customers’ meters.
Seasonality - Gas sales follow a seasonal pattern with an annual base-load of gas and a large heating peak occurring during the winter season. Natural gas obtained from producers, marketers and brokers, as well as gas in storage, is utilized to meet

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the peak heating season requirements. Storage contracts generally allow IPL and WPL to purchase gas in the summer and inject it into underground storage fields, and remove it from storage fields in the winter to deliver to customers.
Competition - Gas customers in Iowa and Wisconsin currently do not have the ability to choose their gas distributor, and IPL and WPL have obligations to serve all their gas customers. While the gas utility distribution function is expected to remain a regulated function, sales of the natural gas commodity and related services are subject to competition from third-parties who provide alternative fuel sources (e.g. propane). However, when natural gas service is available for a given area, customers in such area have generally selected natural gas over propane as a more cost competitive solution for their fuel needs. Refer to “Customer Investments” in MDA for discussion of plans to expand gas distribution systems.
Gas Supply - IPL and WPL maintain purchase agreements with numerous suppliers of natural gas from various gas producing regions of the U.S. and Canada. In providing gas commodity service to retail customers, Corporate Services administers a diversified portfolio of transportation and storage contracts on behalf of IPL and WPL. The tariffs for IPL’s and WPL’s retail gas customers provide for subsequent adjustments to their rates for the cost of gas sold to these customers. As a result, natural gas prices do not have a material impact on IPL’s or WPL’s gas margins.
Gas Demand Planning Reserve Margin - IPL and WPL are required to maintain adequate pipeline capacity to ensure they meet their customers’ maximum daily system demand requirements. IPL and WPL currently have planning reserve margins of 2% and 15%, respectively, above their forecasted maximum daily system demand requirements from November 2020 through March 2021.

Gas Operating Information - Alliant Energy | 2020 |  | 2019 |  | 2018
Revenues (in millions): |  |  |  |  |
Residential | $214 |  |  | $259 |  |  | $254 |
Commercial | 107 |  |  | 133 |  |  | 133 |
Industrial | 12 |  |  | 16 |  |  | 15 |
Retail subtotal | 333 |  |  | 408 |  |  | 402 |
Transportation/other | 40 |  |  | 47 |  |  | 45 |
Total | $373 |  |  | $455 |  |  | $447 |
Sales (000s Dths): |  |  |  |  |
Residential | 27,809 |  |  | 30,791 |  |  | 29,356 |
Commercial | 17,996 |  |  | 21,611 |  |  | 21,003 |
Industrial | 3,003 |  |  | 3,448 |  |  | 3,030 |
Retail subtotal | 48,808 |  |  | 55,850 |  |  | 53,389 |
Transportation/other | 102,790 |  |  | 97,135 |  |  | 90,357 |
Total | 151,598 |  |  | 152,985 |  |  | 143,746 |
Retail Customers (End of Period) | 419,994 |  |  | 417,322 |  |  | 415,174 |
Other Selected Gas Data: |  |  |  |  |
Heating degree days (a): |  |  |  |  |
Cedar Rapids, Iowa (IPL) (normal - 6,659) | 6,625 |  |  | 7,262 |  |  | 6,868 |
Madison, Wisconsin (WPL) (normal - 6,955) | 6,789 |  |  | 7,397 |  |  | 7,303 |
Revenue per Dth sold to retail customers | $6.82 |  |  | $7.31 |  |  | $7.53 |
Purchased gas costs per Dth sold to retail customers | $3.67 |  |  | $3.89 |  |  | $4.27 |

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Gas Operating Information | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Revenues (in millions): |  |  |  |  |  |  |  |  |  |  |
Residential | $116 |  |  | $149 |  |  | $152 |  |  | $98 |  |  | $110 |  |  | $102 |
Commercial | 59 |  |  | 75 |  |  | 76 |  |  | 48 |  |  | 58 |  |  | 57 |
Industrial | 8 |  |  | 12 |  |  | 10 |  |  | 4 |  |  | 4 |  |  | 5 |
Retail subtotal | 183 |  |  | 236 |  |  | 238 |  |  | 150 |  |  | 172 |  |  | 164 |
Transportation/other | 25 |  |  | 28 |  |  | 28 |  |  | 15 |  |  | 19 |  |  | 17 |
Total | $208 |  |  | $264 |  |  | $266 |  |  | $165 |  |  | $191 |  |  | $181 |
Sales (000s Dths): |  |  |  |  |  |  |  |  |  |  |
Residential | 14,521 |  |  | 16,078 |  |  | 15,925 |  |  | 13,288 |  |  | 14,713 |  |  | 13,431 |
Commercial | 8,925 |  |  | 10,906 |  |  | 10,707 |  |  | 9,071 |  |  | 10,705 |  |  | 10,296 |
Industrial | 2,062 |  |  | 2,514 |  |  | 2,019 |  |  | 941 |  |  | 934 |  |  | 1,011 |
Retail subtotal | 25,508 |  |  | 29,498 |  |  | 28,651 |  |  | 23,300 |  |  | 26,352 |  |  | 24,738 |
Transportation/other | 39,543 |  |  | 38,323 |  |  | 37,899 |  |  | 63,247 |  |  | 58,812 |  |  | 52,458 |
Total | 65,051 |  |  | 67,821 |  |  | 66,550 |  |  | 86,547 |  |  | 85,164 |  |  | 77,196 |
Retail Customers (End of Period) | 224,927 |  |  | 224,613 |  |  | 224,413 |  |  | 195,067 |  |  | 192,709 |  |  | 190,761 |
Other Selected Gas Data: |  |  |  |  |  |  |  |  |  |  |
Maximum daily winter peak demand (Dth) | 253,439 |  |  | 303,508 |  |  | 264,787 |  |  | 189,439 |  |  | 229,022 |  |  | 220,784 |
Heating degree days (a): |  |  |  |  |  |  |  |  |  |  |
Cedar Rapids, Iowa (IPL) (normal - 6,659) | 6,625 |  | 7,262 |  | 6,868 |  | N/A |  | N/A |  | N/A
Madison, Wisconsin (WPL) (normal - 6,955) | N/A |  | N/A |  | N/A |  | 6,789 |  | 7,397 |  | 7,303
Revenue per Dth sold to retail customers | $7.17 |  | $8.00 |  | $8.31 |  | $6.44 |  | $6.53 |  | $6.63
Purchased gas cost per Dth sold to retail customers | $3.87 |  | $4.06 |  | $4.51 |  | $3.45 |  | $3.70 |  | $3.99

(a)Heating degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base. Normal degree days are calculated using a rolling 20-year average of historical heating degree days.
3) OTHER UTILITY OPERATIONS - STEAM - IPL’s Prairie Creek facility is the primary source of steam for IPL’s two high-pressure steam customers in Iowa. These customers are each under contract through 2025 for taking minimum quantities of annual steam usage, with certain conditions.
ITEM 1A. RISK FACTORS
You should carefully consider each of the risks described below relating to Alliant Energy, IPL and WPL, together with all of the other information contained in this combined report, before making an investment decision with respect to our securities. If any of the following risks develop into actual events, our business, financial condition or results of operations could be materially and adversely affected, and you may lose all or part of your investment.
Risks Related to Business Operations
The outbreak of the novel coronavirus (COVID-19) pandemic could adversely affect our business functions, financial condition, results of operations and cash flows - The continued spread of COVID-19 has resulted in widespread impacts on the economy and could lead to a prolonged reduction in economic activity, disruptions to supply chains and capital markets, and reduced labor availability and productivity. The COVID-19 pandemic has impacted and may continue to impact the economic conditions in our service territories, which may adversely impact our sales and our customers’ abilities to pay their bills. Travel and transportation restrictions and closures of commercial spaces and industrial facilities have been imposed in and across the U.S., including in the service territories in which we operate. Governmental and regulatory responses to COVID-19 include suspending service disconnects, which may increase customer account arrears, possibly increasing our allowance for expected credit losses and decreasing our cash flows.
Closures of commercial spaces and industrial facilities may result in a reduction in demand of electricity and natural gas from commercial and industrial customers. The negative impacts on the economy could adversely impact the market value of the assets that fund our pension plans, which could necessitate accelerated funding of the plans to meet minimum federal government requirements. The negative impacts on the economy could also adversely impact the ability of counterparties to meet contractual payment obligations, including guarantees, or deliver contracted commodities and other goods or services at the contracted price, which could increase company expenses. Our access to the capital markets could be adversely affected by COVID-19, which could cause us to need alternative sources of funding for our operations and for working capital, any of which could increase our cost of capital.
Travel bans and restrictions, quarantines, shelter in place orders and shutdowns may cause disruptions in supply chains or access to labor that may adversely impact our planned construction projects, our ability to satisfy compliance requirements, or our operations, including our ability to maintain reliable electric and gas service. This may cause us to miss milestones on construction projects and experience operational delays, which, in the case of renewable energy projects, could delay our

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completion of such projects past the in-service dates required to qualify for the maximum general renewable tax credits for investments in such renewable energy projects. We have modified certain business practices to be consistent with government restrictions and best practices encouraged by government and regulatory authorities and developed risk mitigation plans for critical items and services required to continue our operations. The effects of these government restrictions could adversely impact implementation of our regulatory plans and our operations. If our workforce contracts COVID-19, it could negatively impact our operations, including our ability to maintain reliable electric and gas service.
The degree to which COVID-19 may impact our business operations, financial condition and results of operations is unknown at this time and will depend on future developments, including the ultimate geographic spread of COVID-19, the severity of the disease, the duration of the outbreak, possible resurgence of the disease at a later date, emergence of variants, speed, efficacy and adoption rates of vaccines, and further actions that may be taken by governmental and regulatory authorities.
A cyber attack may disrupt our operations or lead to a loss or misuse of confidential and proprietary information or potential liability - We operate in an industry that requires the continuous use and operation of sophisticated information technology systems and network infrastructure. We face threats from use of malicious code (such as malware, viruses and ransomware), employee theft or misuse, advanced persistent threats, and phishing attacks. More of our workforce is working remotely due to the COVID-19 pandemic, which has increased the number of devices connected to the internet that impact our operations and therefore increase our exposure to a cyber attack. Cyber attacks targeting electronic control systems used at our generating facilities and for electric and gas distribution systems could result in a full or partial disruption of our electric and/or gas operations. We have relied on a global supply chain for certain components of our operating and technology systems, which may increase our exposure to cyber attacks. Any disruption of these operations could result in a loss of service to customers and a significant decrease in revenues, as well as significant expense to repair system damage and remedy security breaches. Due to the evolving nature of cyber attacks and cyber security, our current safeguards to protect our operating systems and information technology assets may not always be effective. We rely on third parties for software to protect against cyber attacks and we are at risk if such third parties are targets of cyber attacks. If the technology systems were to fail or be breached by a cyber attack or a computer virus, and not be recovered in a timely fashion, we may be unable to fulfill critical business functions and confidential data could be compromised, adversely impacting our financial condition and results of operation.
In addition, we may collect and retain sensitive information, including personal information about our customers, shareowners and employees. In some cases, we outsource administration of certain functions to vendors that could be targets of cyber attacks. For example, we outsource administration of our employee health insurance to Anthem, which was the target of a cyber attack in 2014. Any theft, loss and/or fraudulent use of customer, shareowner, employee or proprietary data as a result of a cyber attack could subject us to significant litigation, liability and costs, as well as adversely impact our reputation with customers and regulators, among others.
Demand for energy may decrease - Our results of operations are affected by the demand for energy in our service territories. Energy demand may decrease due to many things, including proliferation of customer and third party-owned generation, technological advances that reduce the costs of renewable energy and storage solutions for our customers, loss of service territory or franchises, energy efficiency measures, technological advances that increase energy efficiency, third-party disrupters, loss of wholesale customers, the adverse impact of tariffs on our customers, and economic conditions. The loss of sales due to lower demand for energy may increase our rates for remaining customers, as our rates must cover our fixed costs. Increased customer rates may cause decreased demand for energy as customers move to customer and third party-owned generation and implement energy efficiency measures to reduce costs. The loss of customers, the inability to replace those customers with new customers, and the decrease in demand for energy could negatively impact our financial condition and results of operations.
Our strategy includes large construction projects, which are subject to risks - Our strategy includes constructing renewable generating facilities and large-scale additions and upgrades to our electric and gas distribution systems. These construction projects are subject to various risks. These risks include: the inability to obtain necessary permits in a timely manner; adverse interpretation or enforcement of permit conditions; changes in applicable laws or regulations; changes in costs of materials, equipment, commodities, fuel or labor; delays caused by construction accidents or injuries; shortages in materials, equipment and qualified labor; changes to the scope or timing of the projects; general contractors or subcontractors not performing as required under their contracts; the inability to agree to contract terms or disputes in contract terms; poor initial cost estimates; work stoppages; adverse weather conditions; government actions; legal action; unforeseen engineering or technology issues; limited access to capital or other proposed financing arrangements such as tax equity financing; and other adverse economic conditions. We may not be able to recover all costs for the projects in rates and face increased risk of potential impairment of our project investment if a construction project is not completed or is delayed, or final costs exceed expectations or the costs approved by our regulators. Inability to recover costs, or inability to complete projects in a timely manner, could adversely impact our financial condition and results of operations.
Our utility business is seasonal and may be adversely affected by the impacts of weather - Electric and gas utility businesses are seasonal businesses. Demand for electricity is greater in the summer months associated with higher air conditioning needs and winter months associated with higher heating needs. Demand for natural gas depends significantly upon temperature patterns in winter months due to heavy use in residential and commercial heating. As a result, our overall

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operating results in the future may fluctuate substantially on a seasonal basis. In addition, we have historically generated less revenues and income when temperatures are warmer in the winter and/or cooler in the summer. Thus, mild winters and/or summers could have an adverse impact on our financial condition and results of operations.
We face risks associated with operating electric and natural gas infrastructure - The operation of electric generation and distribution infrastructure involves many risks, including start-up risks, breakdown or failure of equipment, fires developing from our power lines, transformers or substations, dam failure at one of our hydroelectric facilities, the dependence on a specific fuel source, including the supply and transportation of fuel, the risk of performance below expected or contracted levels of output or efficiency, public and employee safety, operator error and ruptured oil and chemical tanks. The operation of our natural gas transmission and distribution infrastructure also involves many risks, such as leaks, explosions, mechanical problems and employee and public safety. Our electric and natural gas infrastructure is aging, which increases certain of these risks. In addition, the North American electric transmission grid is highly interconnected and, in extraordinary circumstances, disruptions at particular points within the grid could cause an extensive power outage in our service territories. Increased utilization of customer- and third party-owned generation technologies could also disrupt the reliability and balance of the electricity grid. Further, the electric transmission system in our utilities’ service territories can experience constraints, limiting the ability to transmit electricity within our service territories. The transmission constraints could result in an inability to deliver electricity from generating facilities, particularly wind generating facilities, to the national grid, or to access lower cost sources of electricity.
These risks could cause significant harm to employees and customers including loss of human life, significant damage to property, adverse impacts on the environment and impairment of our operations, all of which could result in substantial financial losses to us. We are also responsible for compliance with new and changing regulatory standards involving safety, reliability and environmental compliance, including regulations under the Pipeline and Hazardous Materials Safety Administration. Failure to meet these regulatory standards could result in substantial fines. Lastly, we have obligations to provide electric and natural gas service to customers under regulatory requirements and contractual commitments. Failure to meet our service obligations could adversely impact our financial condition and results of operations.
Storms or other natural disasters may impact our operations in unpredictable ways - Storms and other natural disasters, including events such as floods, tornadoes, windstorms like the 2020 derecho in Iowa, blizzards, ice storms, extreme hot temperatures, extreme cold temperatures, fires, solar flares or pandemics may adversely impact our ability to generate, purchase or distribute electric energy and gas or obtain fuel or other critical supplies. In addition, we could incur large costs to repair damage to our generating facilities and electric and gas infrastructure, or costs related to environmental remediation, due to storms or other natural disasters. The restoration costs may not be fully covered by insurance policies and may not be fully recovered in rates, or recovery in rates may be delayed. Storms and natural disasters may impact our customers and the resulting reduced demand for energy could cause lower sales and revenues, which may not be replaced or recovered in rates, or rate recovery may be delayed. Any of these items could adversely impact our financial condition and results of operations.
Threats of terrorism and catastrophic events that could result from terrorism may impact our operations in unpredictable ways - We are subject to direct and indirect effects of terrorist threats and activities. Generation, transmission and distribution facilities, in general, have been identified as potential targets of physical or cyber attacks. Physical attacks on transmission and distribution facilities that appeared to be terrorist-style attacks have occurred. Our gas distribution system could also be the target of terrorist threats and activities. The risks posed by such attacks could include, among other things, the inability to generate, purchase or distribute electric energy or obtain fuel sources, the increased cost of security and insurance, the disruption of, volatility in, or other effects on capital markets, and a decline in the economy and/or energy usage within our service territories, all of which could adversely impact our financial condition and results of operations. In addition, the cost of repairing damage to our facilities and infrastructure caused by acts of terrorism, and the loss of revenue if such events prevent us from providing utility service to our customers, could adversely impact our financial condition and results of operations.
We may not be able to fully recover costs related to commodity prices - We have natural gas and coal supply and transportation contracts in place for some of the natural gas and coal we require to generate electricity. We also have transportation and supply agreements in place to facilitate delivery of natural gas to our customers. Our counterparties to these contracts may not fulfill their obligations to provide natural gas or coal to us due to financial or operational problems caused by natural disasters, severe weather, economic conditions, pandemics, physical attacks or cyber attacks. If we were unable to obtain enough natural gas or coal for our electric generating facilities under our existing contracts, or to obtain electricity under existing or future purchased power agreements, we could be required to purchase natural gas or coal at higher prices or forced to purchase electricity from higher-cost generating resources in the Midcontinent Independent System Operator, Inc. (MISO) energy market. We may be obligated to pay for coal deliveries under our contracts even if our coal-fired generating facilities do not operate enough to fully utilize the amounts of coal covered by the contracts. If, for natural gas delivery to our customers, we were unable to obtain our natural gas supply requirements under existing or future natural gas supply and transportation contracts, we could be required to purchase natural gas at higher prices from other sources. Natural gas market prices have been volatile in the past and could be volatile in the future due to additional future regulations, periods of extremely cold temperatures or disruption in supply caused by major storms or pipeline explosions. We may not be able to pass on all of the changes in costs to our customers, especially at WPL where we do not have an automatic retail electric fuel

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cost adjustment clause to timely recover such costs. Increases in prices and costs due to disruptions that are not recovered in rates fully, in a timely manner, may adversely impact our financial condition and results of operations.
Energy industry changes could have a negative effect on our businesses - We operate in a highly regulated business environment. The advent of new and unregulated markets has the potential to significantly impact our financial condition and results of operations. Further, competitors may not be subject to the same operating, regulatory and financial requirements that we are, potentially causing a substantial competitive disadvantage for us. Changes in public policy that could be the result of a new Presidential Administration, such as new tax incentives that we cannot take advantage of or efforts to deregulate the utility industry, could provide an advantage to competitors. Changes in technology could also alter the channels through which electric customers buy or utilize power, which could reduce the revenues or increase the expenses of our utility companies. Increased competition in our primary retail electric service territories may have an adverse impact on our financial condition and results of operations.
We face risks related to non-utility operations - We rely on our non-utility operations for a portion of our earnings. If our non-utility holdings do not perform at expected levels, we could experience an adverse impact on our financial condition and results of operations.
Risks Related to Laws and Regulations
Our utility business is significantly impacted by government legislation, regulation and oversight - Our utility financial condition is influenced by how regulatory authorities, including the IUB, the PSCW and FERC, establish the rates we can charge our customers, our authorized rates of return and common equity levels, and the costs that may be recovered from customers. Our ability to timely obtain rate adjustments to earn authorized rates of return depends upon timely regulatory action under applicable statutes and regulations, and cannot be guaranteed. In future rate reviews, IPL and WPL may not receive an adequate amount of rate relief to recover all costs and earn their authorized rates of return, rates may be reduced, rate refunds may be required, rate adjustments may not be approved on a timely basis, costs may not be otherwise recovered through rates, future rates may be temporarily frozen, certain rate base items may not receive a full weighted average cost of capital, and authorized rates of return on capital may be reduced. As a result, we may experience adverse impacts on our financial condition and results of operations.
In addition, our operations are subject to extensive regulation primarily by the IUB, the PSCW and FERC. We are also subject to oversight and monitoring by organizations such as the North American Electric Reliability Corporation, the Midwest Reliability Organization, the Pipeline and Hazardous Materials Safety Administration, and MISO. The impacts on our operations include: our ability to site and construct new generating facilities, such as renewable energy projects, and recover associated costs, including our ability to continue to use a renewable energy rider in Iowa; our ability to decommission generating facilities and recover related costs and the remaining carrying value of these facilities and related assets; the rates paid to transmission operators and how those costs are recovered from customers, including our ability to continue to use a transmission rider in Iowa; our ability to site, construct and recover costs for new natural gas pipelines; our ability to recover costs to upgrade our electric and gas distribution systems; the amount of certain sources of energy we must use, such as renewable sources; our ability to purchase generating facilities and recover the costs associated therewith; our ability to sell utility assets and any conditions placed upon the sale of such assets; our ability to enter into purchased power agreements and recover the costs associated therewith; resource adequacy requirements, energy capacity standards, and when new facilities such as IPL’s and WPL’s planned additional solar generation may be fully accredited with energy capacity; the allocation of expenditures by transmission companies on transmission network upgrades and our ability to recover costs associated therewith; reliability; safety; the issuance of securities and ability to use other financing arrangements, such as tax equity financing to finance renewable energy projects; accounting matters; and transactions between affiliates. These regulatory authorities and organizations are also empowered to impose financial penalties and other sanctions, including requirements to implement new compliance programs. Failure to obtain approvals for any of these matters in a timely manner, or receipt of approvals with uneconomical conditions, may cause us not to pursue the construction of such projects or to record an impairment of our assets and may have a material adverse impact on our financial condition and results of operations. Changes to these regulations could materially increase our costs or cause us to reconsider our strategy, which could have a material adverse impact on our financial condition and results of operations.
Provisions of the Wisconsin Utility Holding Company Act may limit our ability to invest in or grow our non-utility activities and may deter potential purchasers who might be willing to pay a premium for our stock.
Changes to certain tax elections, tax regulations and future taxable income could negatively impact our financial condition and results of operations - We have significantly reduced our federal and state income tax obligations through tax planning strategies and the utilization of bonus depreciation deductions for certain expenditures for property. These tax planning strategies and bonus depreciation deductions have generated large taxable losses and tax credits that have resulted in significant federal and state net operating losses and tax credit carryforwards. We plan to utilize substantially all of these net operating losses and tax credit carryforwards in the future to reduce our income tax obligations. If we cannot generate enough taxable income in the future to utilize all of the net operating losses and tax credit carryforwards before they expire due to lower than expected financial performance or changes to tax regulations, we may incur material charges to earnings. In addition, our tax liability is determined by our taxable income multiplied by the current tax rates in effect. If the tax rates are

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increased or a minimum corporate income tax is implemented, as has been proposed by the new Presidential Administration, we may experience adverse impacts to our financial condition and results of operations.
Our utility business currently operates wind generating facilities, which generate production tax credits for us to use to reduce our federal tax obligations. The amount of production tax credits we earn is dependent on the date the qualifying generating facilities are placed in-service, the level of electricity output generated by our qualifying generating facilities and the applicable tax credit rate. If there is a disagreement on the in-service date, the amount of production tax credits that we can generate may be significantly reduced. A variety of operating and economic parameters, including transmission constraints, the imbalance of supply and demand of wind energy resulting in unfavorable pricing for wind energy, adverse weather conditions and breakdown or failure of equipment, could significantly reduce the production tax credits generated by our wind farms resulting in a material adverse impact on our financial condition and results of operations. Our strategic plan includes developing solar generating facilities, which are expected to generate investment tax credits. Investment tax credits are dependent on the date the qualifying generating facilities begin construction and the costs of the qualifying generating facilities. If there is a disagreement on the dates construction began and ended or the qualifying costs, the amount of investment tax credits awarded may be significantly reduced, possibly adversely impacting our financial condition and results of operations.
Our utility businesses are subject to numerous environmental laws and regulations - Our utilities are subject to numerous federal, regional, state and local environmental laws, regulations, court orders, and international treaties. These laws, regulations and court orders generally concern emissions into the air, discharges into water, use of water, wetlands preservation, remediation of contamination, waste disposal, disposal of coal combustion residuals, hazardous waste disposal, threatened and endangered species, and noise regulation, among others. Failure to comply with such laws, regulations and court orders, or to obtain or comply with any necessary environmental permits pursuant to such laws and regulations, could result in injunctions, fines or other sanctions. Environmental laws and regulations affecting power generation and electric and gas distribution are complex and subject to continued uncertainty and could be changed by the new Presidential Administration. These laws and regulations have imposed, and proposed laws and regulations could impose in the future, additional costs on our utility operations. We have incurred, and will continue to incur, capital and other expenditures to comply with these and other environmental laws and regulations. Changes in or new development of environmental restrictions may force us to incur significant expenses or expenses that may exceed our estimates. There can be no assurance that we would be able to recover all or any increased environmental costs from our customers. Failure to comply with the laws, regulations and court orders, changes in the laws and regulations and failure to recover costs of compliance may adversely impact our financial condition and results of operations.
Actions related to global climate change and reducing greenhouse gases (GHG) emissions could negatively impact us - Regulators, customers and investors continue to raise concerns about climate change and GHG emissions. National regulatory action is in flux and international regulatory actions continue to evolve. We are focused on executing a long-term strategy to deliver reliable and affordable energy with lower carbon dioxide (CO2) emissions independent of changing policies and political landscape. However, it is unclear how these climate change concerns will ultimately impact us. We could incur costs or other obligations to comply with future GHG regulations, and could become the target of legal claims or challenges, because generating electricity using fossil fuels emits CO2 and other GHG. Further, investors may determine that we are too reliant on fossil fuels, reducing demand for our stock, which may cause our stock price to decrease, or not buy our debt securities, which may cause our cost of capital to increase. We could face additional pressures from customers, investors or other stakeholders to more rapidly reduce CO2 emissions on a voluntary-basis, including faster adoption of lower CO2 emitting technologies and management of excess renewable energy credits. The timing and pace to fully achieve decarbonization is also contingent on the future development of technologies to reliably store and manage electricity, as well as electrification of other economic sectors. The EPA’s approach and timing for implementing rules to regulate CO2 emissions at fossil-fuel fired electric generating units remains undecided and subject to litigation and could change based on the new Presidential Administration. Various legislative and regulatory proposals to address climate change at the national, state and local levels continue to be introduced. Regulation or legislation mandating CO2 emissions reductions or other clean energy standards could materially increase costs, causing some electric generating units to be uneconomical to operate or maintain. We are vulnerable to potential risks associated with transition to a lower-carbon economy that may extend to our supply chain and natural gas operations. Furthermore, acute and chronic physical risks could disrupt our operations or affect our property. We cannot provide any assurance regarding the potential impacts of climate change policy or GHG regulations on our operations and these could have a material adverse impact on our financial condition and results of operations.
Risks Related to Economic, Financial and Labor Market Conditions
We are subject to employee workforce factors that could affect our businesses - We operate in an industry that requires specialized technical skills. Further, we must build a work force that is innovative, customer-focused and competitive to thrive in the future in order to successfully implement our strategy. It may be difficult to hire and retain such a skilled workforce due to labor market conditions, such as low unemployment rates in our service territories, the length of time employees need to acquire the skills, and general competition for talent. We are also subject to collective bargaining agreements covering approximately 1,800 employees. Any work stoppage experienced in connection with negotiations of collective bargaining agreements could adversely affect our financial condition and results of operations as well as our ability to implement our strategy.

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We are subject to limitations on our ability to pay dividends - Alliant Energy is a holding company with no significant operations of its own. The primary sources of funds for Alliant Energy to pay dividends to its shareowners are dividends and distributions from its subsidiaries, primarily its utility subsidiaries. Our subsidiaries are separate and distinct legal entities and have no obligation to pay any amounts to Alliant Energy, whether by dividends, distributions, loans or other payments. The ability of our subsidiaries to pay dividends or make distributions to Alliant Energy and, accordingly, our ability to pay dividends on Alliant Energy common stock will depend on regulatory limitations, earnings, cash flows, capital requirements and general financial condition of our subsidiaries. Our utilities have dividend payment restrictions based on the terms of any outstanding preferred stock and regulatory limitations applicable to them. If we do not receive adequate dividends and distributions from our subsidiaries, then we may not be able to make, or may have to reduce, dividend payments on Alliant Energy common stock.
We may incur material post-closing adjustments related to past asset and business divestitures - We have sold certain non-utility subsidiaries such as Whiting Petroleum Corporation (Whiting Petroleum). We may continue to incur liabilities relating to our previous ownership of, or the transactions pursuant to which we disposed of, these subsidiaries and assets. Any potential liability depends on a number of factors outside of our control, including the financial condition of Whiting Petroleum, certain of its partners, and/or their assignees. Any required payments on retained liabilities, guarantees or indemnification obligations with respect to Whiting Petroleum or other past and future asset or business divestitures could adversely impact our financial condition and results of operations.
We are dependent on the capital markets and could be negatively impacted by disruptions in the capital markets - Successful implementation of our strategy is dependent upon our ability to access the capital markets. We have forecasted capital expenditures of approximately $6 billion over the next four years. Disruption, uncertainty or volatility in the capital markets could increase our cost of capital or limit our ability to raise funds needed to operate our businesses. Disruptions could be caused by Federal Reserve policies and actions, currency concerns, economic downturn or uncertainty, monetary policies, a negative view of the utility industry or our company, failures of financial institutions, U.S. debt management concerns, U.S. debt limit and budget debates, including government shutdowns, European and worldwide sovereign debt concerns, other global or geopolitical events, or other factors. Increases in interest rates may cause the price of our equity securities to decline. Any disruptions in capital markets could adversely impact our ability to implement our strategy.
We rely on our strong credit ratings to access the credit markets. If our credit ratings are downgraded for any reason, such as worsening credit metric impacts, negative changes to our regulatory environment, or general negative outlook for the utility industry, we could pay higher interest rates in future financings, the pool of potential lenders could be reduced, borrowing costs under existing credit facilities could increase, our access to the commercial paper market could be limited, or we could be required to provide additional credit assurance, including cash collateral, to contract counterparties. If our access to capital were to become significantly constrained or costs of capital increased significantly due to lowered credit ratings, prevailing industry conditions, regulatory constraints, volatility of the capital markets or other factors, our financial condition and results of operations could be adversely affected.
Our pension and other postretirement benefits plans are subject to investment and interest rate risk that could negatively impact our financial condition - We have pension and other postretirement benefits plans that provide benefits to many of our employees and retirees. Costs of providing benefits and related funding requirements of these plans are subject to changes in the liabilities of the plans and market value of the assets that fund the plans. The funded status of the plans and the related costs reflected in our financial statements are affected by various factors, which are subject to an inherent degree of uncertainty, including economic conditions, financial market performance, interest rates, life expectancies and demographics. Recessions and volatility in the domestic and international financial markets have negatively affected the asset values of our pension plans at various times in the past. Poor investment returns or lower interest rates may necessitate accelerated funding of the plans to meet minimum federal government requirements, which could have an adverse impact on our financial condition and results of operations.
ITEM 1B. UNRESOLVED STAFF COMMENTS
None.
ITEM 2. PROPERTIES
Alliant Energy - As a holding company, Alliant Energy doesn’t directly own any significant properties other than the stock of its subsidiaries. The principal properties of those subsidiaries are as follows:

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IPL and WPL
Electric - At December 31, 2020, IPL’s and WPL’s EGUs by primary fuel type were as follows:

IPL |  |  |  |  |  |  |  | Nameplate |  | Generating
|  |  |  | In-service |  |  |  | Capacity |  | Capacity
Name of EGU and Location |  |  |  | Dates |  |  |  | in MW |  | in MW (a)
Marshalltown Generating Station (Units 1-3); Marshalltown, IA |  |  |  | 2017 |  |  |  | 706 |  | 622
Emery Generating Station (Units 1-3); Mason City, IA |  |  |  | 2004 |  |  |  | 603 |  | 529
Marshalltown Combustion Turbines (Units 1-3); Marshalltown, IA |  |  |  | 1978 |  |  |  | 189 |  | 142
Prairie Creek Generating Station (Unit 4); Cedar Rapids, IA |  |  |  | 1967 |  |  |  | 149 |  | 107
Burlington Combustion Turbines (Units 1-4); Burlington, IA |  |  |  | 1994-1996 |  |  |  | 79 |  | 38
Total Gas |  |  |  |  |  |  |  | 1,726 |  | 1,438
Upland Prairie (121 Units); Clay and Dickinson Cos., IA |  |  |  | 2019 |  |  |  | 299 |  | 106
Whispering Willow - North (81 Units); Franklin Co., IA |  |  |  | 2020 |  |  |  | 201 |  | 33
Whispering Willow - East (121 Units); Franklin Co., IA |  |  |  | 2009 |  |  |  | 200 |  | 31
Golden Plains (82 Units); Winnebago and Kossuth Cos., IA |  |  |  | 2020 |  |  |  | 200 |  | 33
English Farms (69 Units); Poweshiek Co., IA |  |  |  | 2019 |  |  |  | 172 |  | 40
Richland (53 Units); Sac Co., IA |  |  |  | 2020 |  |  |  | 131 |  | —
Franklin County (60 Units); Franklin Co., IA |  |  |  | 2012 |  |  |  | 99 |  | 16
Total Wind |  |  |  |  |  |  |  | 1,302 |  | 259
Ottumwa Generating Station (Unit 1); Ottumwa, IA (b) |  |  |  | 1981 |  |  |  | 348 |  | 318
Lansing Generating Station (Unit 4); Lansing, IA |  |  |  | 1977 |  |  |  | 275 |  | 209
Burlington Generating Station (Unit 1); Burlington, IA |  |  |  | 1968 |  |  |  | 212 |  | 189
George Neal Generating Station (Unit 4); Sioux City, IA (c) |  |  |  | 1979 |  |  |  | 179 |  | 156
George Neal Generating Station (Unit 3); Sioux City, IA (d) |  |  |  | 1975 |  |  |  | 164 |  | 137
Prairie Creek Generating Station (Units 1 and 3); Cedar Rapids, IA |  |  |  | 1958-1997 |  |  |  | 65 |  | 26
Louisa Generating Station (Unit 1); Louisa, IA (e) |  |  |  | 1983 |  |  |  | 32 |  | 28
Total Coal |  |  |  |  |  |  |  | 1,275 |  | 1,063
Lime Creek Combustion Turbines (Units 1-2); Mason City, IA |  |  |  | 1991 |  |  |  | 90 |  | 64
Total Oil |  |  |  |  |  |  |  | 90 |  | 64
Dubuque Solar Garden; Dubuque, IA |  |  |  | 2017 |  |  |  | 5 |  | 2
Marshalltown Solar Garden; Marshalltown, IA |  |  |  | 2020 |  |  |  | 3 |  | 1
Total Solar |  |  |  |  |  |  |  | 8 |  | 3
Total capacity |  |  |  |  |  |  |  | 4,401 |  | 2,827

WPL |  |  |  |  |  |  |  | Nameplate |  | Generating
|  |  |  | In-service |  |  |  | Capacity |  | Capacity
Name of EGU and Location |  |  |  | Dates |  |  |  | in MW |  | in MW (a)
Riverside Energy Center (Units 1-3); Beloit, WI |  |  |  | 2004 |  |  |  | 675 |  | 534
West Riverside Energy Center (Units 1-3); Beloit, WI (f) |  |  |  | 2020 |  |  |  | 664 |  | 529
Neenah Energy Facility (Units 1-2); Neenah, WI |  |  |  | 2000 |  |  |  | 371 |  | 295
South Fond du Lac Combustion Turbines (2 Units); Fond du Lac, WI (g) |  |  |  | 1994 |  |  |  | 191 |  | 156
Total Gas |  |  |  |  |  |  |  | 1,901 |  | 1,514
Bent Tree (122 Units); Freeborn Co., MN |  |  |  | 2010-2011 |  |  |  | 201 |  | 29
Kossuth (56 Units); Kossuth Co., IA |  |  |  | 2020 |  |  |  | 152 |  | —
Cedar Ridge (41 Units); Fond du Lac Co., WI |  |  |  | 2008 |  |  |  | 68 |  | 9
Forward Wind Energy Center (37 Units); Dodge and Fond du Lac Cos., WI (i) |  |  |  | 2008 |  |  |  | 59 |  | 8
Total Wind |  |  |  |  |  |  |  | 480 |  | 46
Columbia Energy Center (Units 1-2); Portage, WI (h) |  |  |  | 1975-1978 |  |  |  | 595 |  | 562
Edgewater Generating Station (Unit 5); Sheboygan, WI |  |  |  | 1985 |  |  |  | 414 |  | 390
Total Coal |  |  |  |  |  |  |  | 1,009 |  | 952
Prairie du Sac Hydro Plant (8 Units); Prairie due Sac, WI |  |  |  | 1914-1940 |  |  |  | 33 |  | 12
Kilbourn Hydro Plant (4 Units); Wisconsin Dells, WI |  |  |  | 1926-1939 |  |  |  | 10 |  | 6
Total Hydro |  |  |  |  |  |  |  | 43 |  | 18
Total capacity |  |  |  |  |  |  |  | 3,433 |  | 2,530

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(a)Based on the accredited generating capacity of the EGUs as of December 31, 2020 included in MISO’s resource adequacy process for the planning period from June 2020 through May 2021. Richland and Kossuth did not receive any accredited generating capacity for this planning period since construction was completed after the start of the planning period.
(b)Represents IPL’s 48% ownership interest in this 726 MW (nameplate capacity) / 662 MW (generating capacity) EGU, which is operated by IPL.
(c)Represents IPL’s 25.695% ownership interest in this 696 MW (nameplate capacity) / 608 MW (generating capacity) EGU, which is operated by MidAmerican Energy Company.
(d)Represents IPL’s 28% ownership interest in this 584 MW (nameplate capacity) / 489 MW (generating capacity) EGU, which is operated by MidAmerican Energy Company.
(e)Represents IPL’s 4% ownership interest in this 812 MW (nameplate capacity) / 703 MW (generating capacity) EGU, which is operated by MidAmerican Energy Company.
(f)Represents WPL’s 91.8% ownership interest in this 723 MW (nameplate capacity) / 576 MW (generating capacity) EGU, which is operated by WPL.
(g)Represents Units 2 and 3, which WPL owns. WPL also operates, but does not own, South Fond du Lac Combustion Turbines Units 1 and 4.
(h)Represents WPL’s 53.5% ownership interest in this 1,112 MW (nameplate capacity) / 1,050 MW (generating capacity) EGU, which is operated by WPL.
(i)Represents WPL’s 42.64% ownership interest in this 138 MW (nameplate capacity) / 19 MW (generating capacity) EGU, which is operated by Invenergy Services, LLC.
IPL and WPL own overhead electric distribution line, underground electric distribution cable and substation distribution transformers, substantially all of which are located in Iowa for IPL and Wisconsin for WPL.
Gas - IPL’s and WPL’s gas properties consist primarily of mains and services, meters, regulating and gate stations and other related transmission and distribution equipment. IPL’s and WPL’s gas distribution facilities include gas mains located in Iowa and Wisconsin, respectively.
Other - IPL’s other property includes steam service assets. Refer to Note 10 for information regarding WPL’s lease of the Sheboygan Falls Energy Facility from AEF’s Non-utility Generation business.
Corporate Services - Corporate Services’ property included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2020 consisted primarily of a customer billing and information system for IPL and WPL and other computer software, and the corporate headquarters building located in Madison, Wisconsin.
AEF - AEF’s principal properties included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2020 were as follows:
Non-utility Generation - Includes the Sheboygan Falls Energy Facility, a 347 MW, simple-cycle, natural gas-fired facility near Sheboygan Falls, Wisconsin that was placed in service in 2005 and is leased to WPL. The Sheboygan Falls Energy Facility was accredited with 292 MW of generating capacity for MISO’s resource adequacy process for the planning period from June 2020 through May 2021.
Travero - Includes a short-line rail freight service in Iowa, and a barge, rail and truck freight terminal on the Mississippi River.
ITEM 3. LEGAL PROCEEDINGS
None. SEC regulations require Alliant Energy, IPL and WPL to disclose information about certain proceedings arising under federal, state or local environmental provisions when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions that Alliant Energy, IPL and WPL reasonably believe will exceed a specified threshold. Pursuant to the SEC regulations, Alliant Energy, IPL and WPL use a threshold of $1 million for purposes of determining whether disclosure of any such proceedings is required. Applying this threshold, there are no environmental matters to disclose for this period. Refer to Note 17(c) for discussion of legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business.
ITEM 4. MINE SAFETY DISCLOSURES
None.
INFORMATION ABOUT EXECUTIVE OFFICERS
The executive officers of Alliant Energy, IPL and WPL for which information must be included are the same; however, different positions may be held at the various registrants. None of the executive officers for Alliant Energy, IPL or WPL listed below are related to any member of the Board of Directors or nominee for director or any other executive officer. All of the executive officers have no definite terms of office and serve at the pleasure of the Board of Directors. The executive officers of Alliant Energy, IPL and WPL as of the date of this filing are as follows:

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Table of Cont ents

Name |  | Age as of Filing Date |  | Registrant |  | Positions
John O. Larsen |  | 57 |  | Alliant Energy |  | Mr. Larsen has served as a director since February 2019, and as Chairman of the Board, President and Chief Executive Officer (CEO) since July 2019. He previously served as President and Chief Operating Officer since January 2019, as President from January 2018 to January 2019, and as Senior Vice President (VP) from February 2014 to January 2018.
|  |  |  | IPL |  | Mr. Larsen has served as CEO since January 2019, as a director since February 2019, and as Chairman of the Board since July 2019. He previously served as Senior VP since February 2014.
|  |  |  | WPL |  | Mr. Larsen has served as CEO since January 2019, as a director since February 2019, and as Chairman of the Board since July 2019. He previously served as President since December 2010.
Robert J. Durian |  | 50 |  | Alliant Energy, IPL and WPL |  | Mr. Durian has served as Executive VP and Chief Financial Officer (CFO) since February 2020. He previously served as Senior VP and CFO since February 2019; as Senior VP, CFO and Treasurer from January 2018 to February 2019; as VP, CFO and Treasurer from December 2016 to January 2018; as VP, Chief Accounting Officer (CAO) and Treasurer from July 2016 to December 2016; and as VP, CAO and Controller from July 2015 to July 2016.
James H. Gallegos |  | 60 |  | Alliant Energy, IPL and WPL |  | Mr. Gallegos has served as Executive VP, General Counsel and Corporate Secretary since February 2020. He previously served as Senior VP, General Counsel and Corporate Secretary since February 2015.
David A. de Leon |  | 58 |  | Alliant Energy and IPL |  | Mr. de Leon has served as Senior VP since January 2019. He previously served as VP since April 2017 and as Director-Generation Construction from February 2014 to April 2017.
|  |  |  | WPL |  | Mr. de Leon has served as President since January 2019. He previously served as VP since April 2017 and as Director-Generation Construction from February 2014 to April 2017.
Terry L. Kouba |  | 62 |  | Alliant Energy and WPL |  | Mr. Kouba has served as Senior VP since January 2019. He previously served as VP since February 2014.
|  |  |  | IPL |  | Mr. Kouba has served as President since January 2019. He previously served as VP since February 2014.
Benjamin M. Bilitz |  | 45 |  | Alliant Energy, IPL and WPL |  | Mr. Bilitz has served as CAO and Controller since December 2016. He previously served as Controller since July 2016 and as Assistant Controller from March 2011 to July 2016.

PART II
ITEM 5. MARKET FOR REGISTRANTS’ COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES
Common Stock Data - Alliant Energy’s common stock trades on the Nasdaq Global Select Market under the symbol “LNT,” and the closing sales price at December 31, 2020 was $51.53.
Shareowners - At December 31, 2020, there were 23,282 holders of record of Alliant Energy’s common stock, including holders through Alliant Energy’s Shareowner Direct Plan. Alliant Energy is the sole common shareowner of all 13,370,788 and 13,236,601 shares of IPL and WPL common stock, respectively, currently outstanding. As a result, there is no established public trading market for the common stock of either IPL or WPL.
Dividends - In November 2020, Alliant Energy announced an increase in its targeted 2021 annual common stock dividend to $1.61 per share, which is equivalent to a quarterly rate of $0.4025 per share, beginning with the February 2021 dividend payment. The timing and amount of future dividends is subject to an approved dividend declaration from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.
Common Stock Repurchases - A summary of Alliant Energy common stock repurchases for the quarter ended December 31, 2020 was as follows:

|  | Total Number |  | Average Price |  | Total Number of Shares |  | Maximum Number (or Approximate
|  | of Shares |  | Paid Per |  | Purchased as Part of |  | Dollar Value) of Shares That May
Period |  | Purchased (a) |  | Share |  | Publicly Announced Plan |  | Yet Be Purchased Under the Plan (a)
October 1 to October 31 |  | 3,624 |  | $54.73 |  | — |  | N/A
November 1 to November 30 |  | 2,605 |  | 56.40 |  | — |  | N/A
December 1 to December 31 |  | 67 |  | 50.60 |  | — |  | N/A
|  | 6,296 |  | 55.38 |  | — |  |

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(a)All shares were purchased on the open market and held in a rabbi trust under the DCP. There is no limit on the number of shares of Alliant Energy common stock that may be held under the DCP, which currently does not have an expiration date.
ITEM 6. SELECTED FINANCIAL DATA
Information for Item 6, Selected Financial Data, has been omitted pursuant to SEC modernization rules that are effective as of the filing date of this report.
ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
This MDA includes information relating to Alliant Energy, IPL and WPL, as well as AEF and Corporate Services. Where appropriate, information relating to a specific entity has been segregated and labeled as such. The following discussion and analysis should be read in conjunction with the Financial Statements and Notes included in this report. Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share. In addition, this MDA includes certain financial information for 2020 compared to 2019. Refer to MDA in the combined 2019 Form 10-K for details on certain financial information for 2019 compared to 2018.
OVERVIEW
Strategy and Mission
Alliant Energy’s mission is to deliver affordable energy solutions and exceptional service that its customers and communities count on - safely, efficiently and responsibly. The mission is supported by a strategy focused on meeting the evolving expectations of customers while providing an attractive return for investors, as well as serving its customers and building strong communities. This strategy includes the following key elements:
Providing affordable energy solutions to customers - Alliant Energy’s strategy focuses on affordable energy solutions that support retention and growth of its existing customers and attract new customers to its service territories.
Key Highlights -
•WPL maintaining flat base rates in 2020 and 2021 by utilizing Federal Tax Reform benefits and lower fuel costs to offset higher revenue requirements from rate base additions.
•IPL’s renewable energy rider became effective February 26, 2020, which allows for annual adjustments to electric rates charged to IPL’s retail electric customers for actual renewable energy costs incurred to fund IPL’s 1,000 MW of wind generating facilities placed in service in 2019 and 2020, and tax benefits.
•Providing $35 million of billing credits to IPL’s retail electric customers beginning in the third quarter of 2020 through June 2021, largely driven by Federal Tax Reform benefits for customers.
•Providing $42 million of billing credits to IPL’s retail electric customers in the second quarter of 2020 through its transmission cost rider for amounts previously collected in rates.
•Significant fuel cost reductions achieved in 2020 and further reductions in fuel cost expected in 2021 as a result of expansion of renewable generation, operating highly efficient, low cost natural gas facilities and shortening the term of IPL’s DAEC PPA by 5 years.
•Changes in recovery amounts for energy efficiency costs through the energy efficiency rider resulted in lower costs for IPL’s retail electric and gas customers in 2020.
Making customer-focused investments - Alliant Energy’s strategic priorities include making significant customer-focused investments toward cleaner energy and sustainable customer solutions. Alliant Energy’s strategy drives a capital allocation process focused on: 1) transitioning its generation portfolio to meet the growing interest of customers for cleaner sources of energy, 2) upgrading its electric and gas distribution systems to strengthen safety and resiliency, as well as enable distributed energy solutions in its service territories, and 3) enhancing its customers’ experience with evolving technology and greater flexibility.
Key Highlights (refer to “Customer Investments” for details) -
•IPL’s completion of more than 500 MW of new wind farms: Whispering Willow North (201 MW in January 2020), Golden Plains (200 MW in March 2020) and Richland (131 MW in September 2020).
•WPL’s completion of the natural gas-fired West Riverside Energy Center (723 MW in May 2020), the Kossuth wind farm (152 MW in October 2020) and the expansion of its gas distribution system in Western Wisconsin in November 2020.
•Planned development and acquisition of additional renewable energy, including approximately 1,000 MW of solar generation at WPL by the end of 2023, approximately 400 MW of solar generation by the end of 2023 at IPL and approximately 100 MW of distributed energy resources, including community solar and energy storage systems beginning in 2021 at IPL. In addition, WPL may also develop additional solar generation and distributed energy resources.
Growing customer demand - Alliant Energy’s strategy supports expanding electric and gas usage in its service territories by promoting electrification initiatives and economic development in the communities it serves.
Key Highlights -
•WPL entered into a wholesale power supply agreement with Consolidated Water Power Company, which was effective January 1, 2021 and is expected to bring approximately 60 MW of load to WPL’s electric system.

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•Alliant Energy has various development-ready sites throughout Iowa and Wisconsin, including the 1,300-acre Big Cedar Industrial Center Mega-site in Cedar Rapids, Iowa, and the 730-acre Prairie View Industrial Center Super Park in Ames, Iowa, which are rail-served ready-to-build manufacturing and industrial sites in close proximity to the regional airport and interstate freeways and access IPL’s electric services. The Big Cedar Industrial Center Mega-site also accesses Travero’s rail and warehousing services. In addition, the Beaver Dam Commerce Park is a 520-acre ready-to-build manufacturing and industrial site in Beaver Dam, Wisconsin, with access to commercial and freight airports, interstate freeways and WPL’s electric services.
COVID-19
The outbreak of COVID-19 has become a global pandemic and Alliant Energy’s service territories are not immune to the challenges presented by COVID-19. Despite these challenges, Alliant Energy, IPL and WPL continue to focus on providing the critical, reliable service their customers depend on, while emphasizing the health and welfare of their employees, customers and communities. Alliant Energy, IPL and WPL have not experienced significant impacts on their overall business operations, financial condition, results of operations or cash flows; however, the degree to which the COVID-19 pandemic may impact such items in the future is currently unknown and will depend on future developments of the pandemic as well as possible additional actions by government and regulatory authorities. Alliant Energy has mitigated the impact of sales declines from COVID-19 by accelerating planned cost transformation activities. Actual and potential impacts from COVID-19 include, but are not limited to, the following:
Operational and Supply Chain Impacts - Alliant Energy has modified certain business practices to help ensure the health and safety of its employees, contractors, customers and vendors consistent with orders and best practices issued by government and regulatory authorities. For example, Alliant Energy implemented its business continuity and pandemic plans for critical items and services, including travel restrictions, physical distancing, working-from-home protocols, and rescheduling of planned EGU outages. Alliant Energy also temporarily suspended service disconnects, waived late payment fees for its customers, and modified reconnect service procedures to ensure continuity of service for customers unable to pay their bills and consistency with regulatory orders.
While Alliant Energy has not experienced any significant issues to-date, it continues to monitor potential disruptions or constraints in materials and supplies from key suppliers. Alliant Energy’s construction projects are currently progressing as planned with added safety protocols, and while it continues to monitor its supply chain, there have been no immediate disruptions. Alliant Energy’s wind farms under construction during the pandemic were placed in service as previously planned to meet the timing requirements to qualify for the maximum renewable tax credits. In addition, Alliant Energy does not currently expect any material changes to its construction and acquisition expenditures plans disclosed in “Liquidity and Capital Resources” resulting from COVID-19.
Alliant Energy has not experienced, and currently does not expect, an interruption in its ability to provide electric and natural gas services to its customers. Alliant Energy currently expects to incur incremental direct expenses related to certain of these operational and supply chain impacts but does not expect them to have a material impact on its results of operations.
Customer Impacts - COVID-19 has resulted in various travel restrictions and closures of commercial spaces and industrial facilities in Alliant Energy’s service territories. While the total expected impact of COVID-19 on future sales is currently unknown, Alliant Energy has experienced higher electric residential sales and lower electric commercial and industrial sales since the outset of the pandemic, and expects these sales trends by customer class to continue into 2021 but at lower impacts than in 2020. In 2020 compared to 2019, Alliant Energy’s retail electric residential temperature-normalized sales increased 3%, and its retail electric commercial and industrial temperature-normalized sales decreased 4% in aggregate. In addition, Alliant Energy has not experienced a material increase in customer bankruptcies in 2020.
Liquidity and Capital Resources Impacts - In response to the uncertainty of the impacts of COVID-19, Alliant Energy enhanced its liquidity position in the first quarter of 2020 by settling $222 million under the equity forward sale agreements and AEF accelerating the refinancing of its $300 million term-loan credit agreement that would have been due in April 2020. Alliant Energy also enhanced its liquidity position by accelerating and/or increasing the size of new debt offerings in 2020, including WPL's issuance of $350 million of debentures due 2050 in April 2020, IPL's issuance of $400 million of senior debentures due 2030 in June 2020 and AEF's issuance of $200 million of senior notes due 2026 in November 2020. Alliant Energy maintains a single credit facility, which allows borrowing capacity to shift among Alliant Energy (at the parent company level), IPL and WPL, as needed. During March and April 2020, Alliant Energy and WPL borrowed under the single credit facility for a portion of their temporary cash needs to obtain more favorable interest rates than available in the commercial paper market at that time. In addition, IPL maintains a sales of accounts receivable program as an alternative financing source; however, if customer arrears were to exceed certain levels, IPL’s access to the program may be restricted.
Alliant Energy, IPL and WPL currently expect to maintain compliance with the financial covenants of the credit facility agreement, and Alliant Energy currently expects to maintain compliance with the financial covenants in AEF’s term loan credit agreement. In addition, Alliant Energy currently expects to have adequate liquidity to fulfill its contractual obligations, access to capital markets and continue with its planned quarterly dividend payments.

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Credit Risk Impacts - Alliant Energy’s temporary suspension of service disconnects and waivers of late payment fees for its customers, as well as broad economic factors, may negatively impact its customers’ willingness and ability to pay, which could increase customer arrears and bad debts, and negatively impact Alliant Energy’s cash flows from operations. Currently, Alliant Energy does not anticipate any material credit risk related to its commodity transactions.
Regulatory Impacts - In March 2020, WPL received authorization from the PSCW to defer certain incremental costs incurred resulting from COVID-19, including bad debt expenses and foregone revenues from late payment fees. In August 2020, IPL received authorization from the IUB for utilization of a regulatory asset account to track increased expenses and other financial impacts incurred after March 1, 2020 resulting from COVID-19. The recovery of any authorized deferrals will be addressed in future regulatory proceedings. In 2020, such amounts were not material.
Legislative Impacts - In March 2020, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was enacted. The most significant provision of the CARES Act for Alliant Energy relates to an acceleration of refunds of existing alternative minimum tax credits to increase liquidity. In July 2020, Alliant Energy received $11 million of credits that otherwise would have been received in 2021 and 2022. In addition, Alliant Energy has deferred certain 2020 payroll taxes to 2021 and 2022. The CARES Act also provides additional funding to the Low Income Home Energy Assistance Program, which assists certain of Alliant Energy’s customers with managing their energy costs, as well as financial support for certain of Alliant Energy’s residential, small business and non-profit customers.
In December 2020, the Coronavirus Response and Relief Supplemental Appropriations Act of 2021 (CRRSA) was enacted. The most significant provision of the CRRSA Act for Alliant Energy relates to the extension of certain renewable tax credits, and as a result, Alliant Energy will evaluate additional opportunities for repowering of its existing wind farms and additional solar projects beyond 2023. The CRRSA Act also provides additional funding to the Low Income Home Energy Assistance Program, as well as financial support for certain of Alliant Energy’s residential, small business and non-profit customers.
Derecho Windstorm
In August 2020, a derecho windstorm caused considerable damage to IPL’s electric distribution system in its service territory, and over 250,000 of its customers lost power. IPL completed its initial restoration efforts in August 2020 and permanent repairs to the system will continue into 2021. Refer to Note 2 for further discussion, including IPL’s current estimate and requested regulatory treatment of certain incremental costs and benefits incurred resulting from the windstorm.
RESULTS OF OPERATIONS
Results of operations include financial information prepared in accordance with GAAP as well as utility electric margins and utility gas margins, which are not measures of financial performance under GAAP. Utility electric margins are defined as electric revenues less electric production fuel, purchased power and electric transmission service expenses. Utility gas margins are defined as gas revenues less cost of gas sold. Utility electric margins and utility gas margins are non-GAAP financial measures because they exclude other utility and non-utility revenues, other operation and maintenance expenses, depreciation and amortization expenses, and taxes other than income tax expense.
Management believes that utility electric and gas margins provide a meaningful basis for evaluating and managing utility operations since electric production fuel, purchased power and electric transmission service expenses and cost of gas sold are generally passed through to customers, and therefore, result in changes to electric and gas revenues that are comparable to changes in such expenses. The presentation of utility electric and gas margins herein is intended to provide supplemental information for investors regarding operating performance. These utility electric and gas margins may not be comparable to how other entities define utility electric and gas margin. Furthermore, these measures are not intended to replace operating income as determined in accordance with GAAP as an indicator of operating performance.
Additionally, the table below includes EPS for Utilities and Corporate Services, ATC Holdings, and Non-utility and Parent, which are non-GAAP financial measures. Alliant Energy believes these non-GAAP financial measures are useful to investors because they facilitate an understanding of segment performance and trends, and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance.
Financial Results Overview - Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners were as follows (dollars in millions, except per share amounts):

| 2020 |  | 2019
| Income (Loss) |  | EPS |  | Income (Loss) |  | EPS
Utilities and Corporate Services | $586 |  | $2.36 |  |  | $529 |  | $2.22 |
ATC Holdings | 34 |  | 0.14 |  |  | 34 |  | 0.14 |
Non-utility and Parent | (6) |  | (0.03) |  |  | (6) |  | (0.03) |
Alliant Energy Consolidated | $614 |  | $2.47 |  |  | $557 |  | $2.33 |

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Alliant Energy’s Utilities and Corporate Services income increased $57 million in 2020 compared to 2019. The increase was primarily due to higher earnings resulting from IPL’s and WPL’s increasing rate base. This item was partially offset by higher depreciation expense, lower AFUDC and higher WPL electric fuel-related costs, net of recoveries.
Operating income and a reconciliation of utility electric and gas margins to the most directly comparable GAAP measure, operating income, was as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  |  |  | 2020 |  | 2019 |  |  |  | 2020 |  | 2019 |  |
Operating income | $740 |  |  | $778 |  |  |  |  | $410 |  |  | $403 |  |  |  |  | $306 |  |  | $347 |  |  |
Electric utility revenues | $2,920 |  |  | $3,064 |  |  |  |  | $1,695 |  |  | $1,781 |  |  |  |  | $1,225 |  |  | $1,283 |  |  |
Electric production fuel and purchased power expenses | (652) |  |  | (777) |  |  |  |  | (352) |  |  | (435) |  |  |  |  | (300) |  |  | (342) |  |  |
Electric transmission service expense | (449) |  |  | (481) |  |  |  |  | (298) |  |  | (340) |  |  |  |  | (151) |  |  | (141) |  |  |
Utility Electric Margin (non-GAAP) | 1,819 |  |  | 1,806 |  |  |  |  | 1,045 |  |  | 1,006 |  |  |  |  | 774 |  |  | 800 |  |  |
Gas utility revenues | 373 |  |  | 455 |  |  |  |  | 208 |  |  | 264 |  |  |  |  | 165 |  |  | 191 |  |  |
Cost of gas sold | (182) |  |  | (222) |  |  |  |  | (99) |  |  | (120) |  |  |  |  | (83) |  |  | (102) |  |  |
Utility Gas Margin (non-GAAP) | 191 |  |  | 233 |  |  |  |  | 109 |  |  | 144 |  |  |  |  | 82 |  |  | 89 |  |  |
Other utility revenues | 49 |  |  | 46 |  |  |  |  | 44 |  |  | 44 |  |  |  |  | 5 |  |  | 2 |  |  |
Non-utility revenues | 74 |  |  | 83 |  |  |  |  | — |  |  | — |  |  |  |  | — |  |  | — |  |  |
Other operation and maintenance expenses | (670) |  |  | (712) |  |  |  |  | (375) |  |  | (404) |  |  |  |  | (254) |  |  | (261) |  |  |
Depreciation and amortization expenses | (615) |  |  | (567) |  |  |  |  | (356) |  |  | (327) |  |  |  |  | (254) |  |  | (236) |  |  |
Taxes other than income tax expense | (108) |  |  | (111) |  |  |  |  | (57) |  |  | (60) |  |  |  |  | (47) |  |  | (47) |  |  |
Operating income | $740 |  |  | $778 |  |  |  |  | $410 |  |  | $403 |  |  |  |  | $306 |  |  | $347 |  |  |

Operating Income Variances - Variances between periods in operating income for 2020 compared to 2019 were as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
Total higher (lower) utility electric margin variance (Refer to details below) | $13 |  | $39 |  | ($26)
Total lower utility gas margin variance (Refer to details below) | (42) |  | (35) |  | (7)
Total lower other operation and maintenance expenses variance (Refer to details below) | 42 |  | 29 |  | 7
Higher depreciation and amortization expense primarily due to additional plant in service in 2019 and 2020, including IPL’s new wind generation and WPL’s West Riverside Energy Center | (48) |  | (29) |  | (18)
Other | (3) |  | 3 |  | 3
| ($38) |  | $7 |  | ($41)

Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), were as follows:

| Electric |  |  |  | Gas
| Revenues |  | MWhs Sold |  |  |  | Revenues |  | Dths Sold
| 2020 |  | 2019 |  |  |  | 2020 |  | 2019 |  |  |  | 2020 |  | 2019 |  | 2020 |  | 2019
Alliant Energy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail | $2,652 |  |  | $2,751 |  |  |  |  | 24,535 |  |  | 25,121 |  |  |  |  | $333 |  |  | $408 |  |  | 48,808 |  |  | 55,850 |
Sales for resale | 204 |  |  | 250 |  |  |  |  | 6,046 |  |  | 6,594 |  |  |  |  | N/A |  | N/A |  | N/A |  | N/A
Transportation/Other | 64 |  |  | 63 |  |  |  |  | 71 |  |  | 79 |  |  |  |  | 40 |  |  | 47 |  |  | 102,790 |  |  | 97,135 |
| $2,920 |  |  | $3,064 |  |  |  |  | 30,652 |  |  | 31,794 |  |  |  |  | $373 |  |  | $455 |  |  | 151,598 |  |  | 152,985 |
IPL |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail | $1,564 |  |  | $1,615 |  |  |  |  | 13,830 |  |  | 14,142 |  |  |  |  | $183 |  |  | $236 |  |  | 25,508 |  |  | 29,498 |
Sales for resale | 88 |  |  | 128 |  |  |  |  | 3,485 |  |  | 4,479 |  |  |  |  | N/A |  | N/A |  | N/A |  | N/A
Transportation/Other | 43 |  |  | 38 |  |  |  |  | 34 |  |  | 36 |  |  |  |  | 25 |  |  | 28 |  |  | 39,543 |  |  | 38,323 |
| $1,695 |  |  | $1,781 |  |  |  |  | 17,349 |  |  | 18,657 |  |  |  |  | $208 |  |  | $264 |  |  | 65,051 |  |  | 67,821 |
WPL |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail | $1,088 |  |  | $1,136 |  |  |  |  | 10,705 |  |  | 10,979 |  |  |  |  | $150 |  |  | $172 |  |  | 23,300 |  |  | 26,352 |
Sales for resale | 116 |  |  | 122 |  |  |  |  | 2,561 |  |  | 2,115 |  |  |  |  | N/A |  | N/A |  | N/A |  | N/A
Transportation/Other | 21 |  |  | 25 |  |  |  |  | 37 |  |  | 43 |  |  |  |  | 15 |  |  | 19 |  |  | 63,247 |  |  | 58,812 |
| $1,225 |  |  | $1,283 |  |  |  |  | 13,303 |  |  | 13,137 |  |  |  |  | $165 |  |  | $191 |  |  | 86,547 |  |  | 85,164 |

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Sales Trends and Temperatures - Alliant Energy’s retail electric and gas sales volumes decreased 2% and 13% in 2020 compared to 2019, respectively, primarily due to the impacts from COVID-19, the derecho windstorm, and changes in temperatures in Alliant Energy’s service territories, partially offset by an extra day of sales in 2020 due to leap year. In 2020, COVID-19 impacts on sales volumes resulted in increases for retail electric residential sales volumes and decreases for retail electric commercial and industrial sales volumes.
Estimated increases (decreases) to electric and gas margins from the impacts of temperatures were as follows (in millions):

| Electric Margins |  |  | Gas Margins |
| 2020 |  | 2019 |  |  |  |  |  | 2020 |  | 2019 |  |  |  |
IPL | $1 |  | $10 |  |  |  |  |  | $— |  | $5 |  |  |  |
WPL | 3 |  | 4 |  |  |  |  |  | (1) |  | 3 |  |  |  |
Total Alliant Energy | $4 |  | $14 |  |  |  |  |  | ($1) |  | $8 |  |  |  |

Utility Electric Margin Variances - The following items contributed to increased (decreased) utility electric margins for 2020 compared to 2019 (in millions):

| Alliant Energy |  | IPL |  | WPL
Impact of IPL’s retail electric final and interim rate increases effective February 2020 and April 2019, respectively (a) | $63 |  | $63 |  | $—
Higher revenues at IPL due to credits on customers’ bills in 2019 related to production tax credits through the fuel-related cost recovery mechanism (offset by changes in income tax) | 16 |  | 16 |  | —
Lower purchased electric capacity expense at WPL | 8 |  | — |  | 8
Higher revenues at IPL due to changes in electric tax benefit rider credits on customers’ bills (offset by changes in income tax expense) | 6 |  | 6 |  | —
Higher WPL electric fuel-related costs, net of recoveries | (18) |  | — |  | (18)
Lower revenues at IPL due to credits on customers’ bills in 2020 related to excess deferred amortization through the tax benefit rider (offset by changes in income tax) | (15) |  | (15) |  | —
Changes in timing of collection of electric transmission service costs at WPL | (10) |  | — |  | (10)
Estimated changes in sales volumes caused by temperatures | (10) |  | (9) |  | (1)
Lower revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (offset by changes in energy efficiency expense) | (8) |  | (8) |  | —
Other (includes lower temperature-normalized sales primarily due to the derecho windstorm and COVID-19 impacts) | (19) |  | (14) |  | (5)
| $13 |  | $39 |  | ($26)

(a)IPL’s interim retail electric base rate increase was effective April 1, 2019 and final retail electric base rate increase was effective February 26, 2020. Effective with final rates, the recovery of, and return on, IPL’s new wind generation placed in service in 2019 and 2020 is provided through the renewable energy rider. Both interim and final rate increases include a reduction for anticipated production tax credits for IPL’s new wind generation. This reduction is expected to be offset by a reduction in income tax expense resulting from production tax credits recognized from this new wind generation. Refer to Note 2 for further discussion.
Utility Gas Margin Variances - The following items contributed to increased (decreased) utility gas margins for 2020 compared to 2019 (in millions):

| Alliant Energy |  | IPL |  | WPL
Lower revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (offset by changes in energy efficiency expense) | ($34) |  | ($34) |  | $—
Estimated changes in sales volumes caused by temperatures | (9) |  | (5) |  | (4)
Impact of IPL’s retail gas rate increase effective January 2020 | 11 |  | 11 |  | —
Other (includes lower temperature-normalized sales primarily due to COVID-19 impacts) | (10) |  | (7) |  | (3)
| ($42) |  | ($35) |  | ($7)

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Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for 2020 compared to 2019 (in millions):

| Alliant Energy |  | IPL |  | WPL
Lower energy efficiency expense at IPL (primarily offset by lower electric and gas revenues) | $39 |  | $39 |  | $—
Lower incentive compensation expense | 9 |  | 6 |  | 3
Credit loss adjustments related to guarantees for an affiliate of Whiting Petroleum (Refer to Note 17(d)) | 7 |  | — |  | —
Higher generation operation and maintenance expenses (primarily related to new generation, including wind at IPL and WPL and West Riverside at WPL) | (8) |  | (4) |  | (4)
Other | (5) |  | (12) |  | 8
| $42 |  | $29 |  | $7

Other Income and Deductions Variances - The following items contributed to (increased) decreased other income and deductions for 2020 compared to 2019 (in millions):

| Alliant Energy |  | IPL |  | WPL
Higher interest expense primarily due to higher average outstanding long-term debt balances, partially offset by lower interest rates on short-term debt outstanding at Alliant Energy and WPL | ($2) |  | ($12) |  | ($2)
Lower AFUDC primarily due to changes in CWIP balances related to IPL’s new wind generation and WPL’s West Riverside Energy Center and new wind generation | (38) |  | (26) |  | (12)
Other (Refer to Note 6 for details of increased income from unconsolidated equity investments) | 9 |  | — |  | 3
| ($31) |  | ($38) |  | ($11)

Income Taxes - Refer to Note 12 for details of effective income tax rates.
Other Future Considerations - In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations:
•Financing Plans - WPL currently expects to issue up to $300 million of long-term debt in 2021. Alliant Energy currently expects to issue up to $25 million of common stock in 2021 through its Shareowner Direct Plan.
•Common Stock Dividends - Alliant Energy announced a 6% increase in its targeted 2021 annual common stock dividend to $1.61 per share, which is equivalent to a quarterly rate of $0.4025 per share, beginning with the February 2021 dividend payment. The timing and amount of future dividends is subject to an approved dividend declaration from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.
•Higher Earnings on Increasing Rate Base - Alliant Energy, IPL and WPL currently expect an increase in earnings in 2021 compared to 2020 due to impacts from increasing revenue requirements related to investments in the utility business, including IPL’s and WPL’s wind investments, WPL’s Western Wisconsin gas distribution system expansion, and the impacts of IPL’s DAEC PPA amendment buyout payment.
•Extreme Temperatures - In February 2021, portions of the central and southern U.S., including Alliant Energy’s service territories, experienced a prolonged period of very cold temperatures and a series of winter storms. This resulted in significant volatility and increases in commodity prices caused by higher demand for electricity and natural gas and disruptions in commodity supply. As a result, Alliant Energy currently expects to incur higher electric production fuel and cost of gas sold expenses in 2021 compared to 2020 related to the extreme temperatures and winter storms. Any changes in electric production fuel and cost of gas sold is expected to be recovered through IPL’s and WPL’s cost recovery mechanisms resulting in impacts to customer bills in 2021. As a result of these impacts to customers during a pandemic, Alliant Energy plans to work with the respective commissions to evaluate the recovery of any higher costs over a longer period of time.
•Depreciation and Amortization Expenses - Alliant Energy, IPL and WPL currently expect an increase in depreciation and amortization expenses in 2021 compared to 2020 due to property additions, including IPL’s and WPL’s expansion of wind generation and WPL’s natural gas-fired West Riverside Energy Center.
•Allowance for Funds Used During Construction - Alliant Energy currently expects AFUDC to decrease in 2021 compared to 2020 primarily due to decreased CWIP balances related to IPL’s and WPL’s wind generation and WPL’s West Riverside Energy Center, which were placed in service in 2020.

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CUSTOMER INVESTMENTS
Alliant Energy’s, IPL’s and WPL’s strategic priorities include making significant customer-focused investments toward cleaner energy and sustainable customer solutions. These priorities include:
Environmental Stewardship
Alliant Energy’s environmental stewardship is focused on meeting its customers’ energy needs in an economical, efficient and sustainable manner. Alliant Energy proactively considers future environmental compliance requirements and proposed regulations in its planning, decision-making, construction and ongoing operations activities. Alliant Energy is focused on executing a long-term strategy to deliver reliable and affordable energy with lower emissions independent of changing policies and political landscape. To achieve these long-term goals, Alliant Energy will transition away from coal-fired EGUs and incorporate more renewable energy, distributed energy resources, energy efficiency, demand response, highly-efficient natural gas-fired EGUs and other emerging technologies such as energy storage. Alliant Energy’s voluntary environmental-related goals and achievements include the following:
•Reduced air emissions for sulfur dioxide by 90%, nitrogen oxide by 80% and mercury by 90% from 2005 levels, which it achieved in 2019.
•By 2030, reduce CO2 emissions by 50% and water supply by 75% from 2005 levels from its owned fossil-fueled generation, as well as transition 100% of its light-duty fleet vehicles to be electric.
•By 2040, eliminate all coal-fired EGUs from its generating fleet.
•By 2050, achieve an aspirational goal of net-zero CO2 emissions from the electricity it generates.
Future updates to sustainable energy plans and attaining these goals will depend on future economic developments, evolving energy technologies and emerging trends in Alliant Energy’s service territories.
Renewable Generation
Alliant Energy’s cleaner energy strategy, or Clean Energy Blueprint, includes the planned development and acquisition of additional renewable energy, including approximately 1,000 MW of solar generation at WPL by the end of 2023, approximately 400 MW of solar generation by the end of 2023 at IPL and approximately 100 MW of distributed energy resources, including community solar and energy storage systems beginning in 2021 at IPL. Alliant Energy, IPL and WPL continue to evaluate additional opportunities to add more renewable generation, including repowering of existing wind farms and additional solar generation and distributed energy resources. Estimated capital expenditures for these planned projects for 2021 through 2024 are included in the “Renewable projects” line in the construction and acquisition table in “Liquidity and Capital Resources.” IPL and WPL currently assume that a portion of the construction costs for the new solar generation will be financed by a tax equity partner, which is discussed in “IPL and WPL Solar Project Tax Equity Credits” in “Liquidity and Capital Resources.” In addition, Alliant Energy completed the construction and acquisition of approximately 1,200 MW of wind generation in aggregate (approximately 1,000 MW at IPL and approximately 200 MW at WPL) from 2018 through 2020.
WPL’s Solar Generation - In May 2020, WPL filed a CA with the PSCW for approval to acquire, construct, own, and operate 675 MW of new solar generation in the following Wisconsin counties: Grant (200 MW in 2023), Sheboygan (150 MW in 2022), Wood (150 MW in 2022), Jefferson (75 MW in 2022), Richland (50 MW in 2022) and Rock (50 MW in 2023). The 675 MW of new solar generation would replace energy and capacity being eliminated with the planned retirement of the coal-fired Edgewater Generating Station (414 MW) by the end of 2022, and Columbia Unit 1 by the end of 2023 and Columbia Unit 2 by the end of 2024 (595 MW in aggregate). In addition, WPL currently expects to file a second CA with the PSCW in the first half of 2021 for approximately 325 MW of new solar generation. As a result of WPL’s neighboring utilities anticipated exercise of their options to purchase a partial ownership interest in West Riverside, WPL anticipates additional capacity needs by 2024.
IPL’s Solar Generation and Distributed Energy Resources - IPL’s plans include development and acquisition of up to 400 MW of solar generation by the end of 2023 and up to 100 MW of distributed energy resources, including community solar and energy storage systems beginning in 2021. IPL currently plans to file for advance rate-making principles for up to 400 MW of solar generation in the first half of 2021. The 400 MW of new solar generation would help replace a portion of the energy and capacity expected to be eliminated with the planned retirement of the coal-fired Lansing Generating Station (275 MW) by the end of 2022 and the expected reduction of energy and capacity resulting from the planned fuel switch of the Burlington Generating Station (212 MW) from coal to natural gas by the end of 2021.
IPL’s Expansion of Wind Generation - In 2016 and 2018, IPL received approvals from the IUB for advance rate-making principles for 1,000 MW of new wind generation. IPL completed the construction of various wind farms as follows:

Wind Site |  | Nameplate Capacity |  | In-service Date |  | Location
Upland Prairie |  | 299 MW |  | March 2019 |  | Clay and Dickinson Counties, Iowa
English Farms |  | 172 MW |  | March 2019 |  | Poweshiek County, Iowa
Whispering Willow North |  | 201 MW |  | January 2020 |  | Franklin County, Iowa
Golden Plains |  | 200 MW |  | March 2020 |  | Winnebago and Kossuth Counties, Iowa
Richland |  | 131 MW |  | September 2020 |  | Sac County, Iowa

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WPL’s Expansion of Wind Generation - In October 2020, WPL completed the construction of the Kossuth wind farm (152 MW) in Kossuth County, Iowa, pursuant to approvals from the PSCW. In addition, WPL acquired a partial ownership interest in the assets of the Forward Wind Energy Center located in Wisconsin (59 MW) in 2018, pursuant to approvals from the PSCW and FERC.
Complementary Generation Investments
WPL’s Construction of West Riverside Natural Gas-fired Generating Station - In 2016, WPL received an order from the PSCW authorizing WPL to construct a natural gas-fired combined-cycle EGU in Beloit, Wisconsin, referred to as West Riverside. WPL’s construction of West Riverside began in 2016 and the 723 MW EGU was placed in service in May 2020. West Riverside replaces energy and capacity being eliminated with the retirements of various EGUs.
WPL entered into agreements with neighboring utilities and electric cooperatives that provide each of them options to purchase a partial ownership interest in West Riverside. The purchase price for such options is based on the ownership interest acquired and the net book value of West Riverside on the date of the purchase. The exercise of the WPSC and MGE options is subject to PSCW approval, and the timing and ownership amounts of the options are as follows:

Counterparty |  | Option Amount and Timing
Wisconsin Public Service Corporation (WPSC) |  | Up to 200 MW may be exercised through May 2024 (no more than 100 MW to be acquired prior to May 2022) (a)
Madison Gas and Electric Company (MGE) |  | Up to 50 MW may be exercised through May 2025 (no more than 25 MW to be acquired prior to May 2022)
Electric cooperatives |  | Approximately 60 MW were exercised January 2018

(a)If WPSC exercises its options, WPL may exercise reciprocal options, subject to approval by the PSCW, to purchase up to 200 MW of any natural-gas combined-cycle EGU that either WPSC or its affiliated utility, Wisconsin Electric Power Company, places in service within 10 years of the date West Riverside is placed in service.
Plant Retirements and Fuel Switching - The current strategy includes the retirement, or fuel switch from coal to natural gas, of various EGUs in the next several years. IPL currently expects to retire the coal-fired Lansing Generating Station (275 MW) by the end of 2022 and fuel switch the Burlington Generating Station (212 MW) from coal to natural gas by the end of 2021. WPL currently expects to retire the coal-fired Edgewater Generating Station (414 MW) by the end of 2022, Columbia Unit 1 by the end of 2023 and Columbia Unit 2 by the end of 2024. Alliant Energy, IPL and WPL are working with MISO, state regulatory commissions and other regulatory agencies, as required, to determine the timing of these actions, which are subject to change depending on operational, regulatory, market and other factors. Refer to Note 3 for additional details on these EGUs, as well as Note 17(e) for discussion of IPL’s requirements to fuel switch or retire certain EGUs under a Consent Decree.
Other Customer-focused Investments
Electric and Gas Distribution Systems - Customer-focused investments include replacing, modernizing and upgrading infrastructure in the electric and gas distribution systems. Electric system investments will focus on areas such as improving resiliency with more underground electric distribution and enabling distributed energy solutions with higher capacity lines. Gas system investments will focus on pipeline replacement to ensure safety and pipeline expansion to support reliability and economic development. Estimated capital expenditures for expected and current electric and gas distribution infrastructure projects for 2021 through 2024 are included in the “Electric and gas distribution systems” lines in the construction and acquisition expenditures table in “Liquidity and Capital Resources.”
Fiber Optic Telecommunication Network - Alliant Energy is currently installing fiber optic routes between its facilities to enhance its communications network to improve resiliency and reliability of, and enable and strengthen, the integrated grid network to help serve its customers.
Gas Pipeline Expansion - IPL and WPL currently expect to make investments to extend various gas distribution systems to provide natural gas to unserved or underserved areas in their service territories. In April 2020, WPL received authorization from the PSCW to expand its gas distribution system in Western Wisconsin, which was completed in November 2020.
Gas Pipeline Safety - In October 2019, the Pipeline and Hazardous Materials Safety Administration published a final rule that updates safety requirements for gas transmission pipelines, and various updated procedures were implemented in July 2020. Plans to address certain requirements for specific pipelines must be developed by July 2021, and remediation efforts must be completed by July 2035. In anticipation of these rule changes, Alliant Energy, IPL and WPL have been proactively replacing certain of IPL’s transmission pipelines and making modifications to certain of WPL’s transmission pipelines. Alliant Energy, IPL, and WPL also continue to evaluate the impact of this final rule and resulting remediation plans on their financial condition and results of operations.
Non-utility business - Alliant Energy continues to explore growth of its Travero businesses and other limited scope opportunities outside of, but complimentary to, Alliant Energy’s core utility business. This non-utility strategy continues to evolve through exploration of modest strategic opportunities that are accretive to earnings and cash flows within and outside of Alliant Energy’s service territories.

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RATE MATTERS
Rate Reviews
Retail Base Rate Filings - Base rate changes reflect both returns on additions to infrastructure and recovery of changes in costs incurred or expected to be incurred. Given that a portion of the rate changes will offset changes in costs, revenues from rate changes should not be expected to result in an equal change in net income for either IPL or WPL.
IPL’s Retail Electric and Gas Rate Reviews (2020 Forward-looking Test Period) - In 2019, IPL filed retail electric and gas rate review requests with the IUB covering the 2020 forward-looking Test Period. In January 2020, IPL received an order from the IUB approving IPL’s proposed settlement for its retail electric rate review. Final retail electric rates were effective February 26, 2020. In December 2019, IPL received an order from the IUB approving IPL’s proposed settlement for its retail gas rate review. Final retail gas rates were effective January 10, 2020. Refer to Note 2 for details.
IPL currently expects to file a subsequent proceeding with the IUB in the second quarter of 2021 for its 2020 Forward-looking Test Period retail electric and gas rate reviews, which will compare actual revenues and costs to those initially forecasted by IPL. IPL currently does not expect any rate adjustments from the subsequent proceeding.
WPL’s Retail Electric and Gas Rate Review (2021 Forward-looking Test Period) - In December 2020, the PSCW issued an order authorizing WPL to maintain its current retail electric and gas base rates, authorized return on common equity, regulatory capital structure and earnings sharing mechanism through the end of 2021. WPL will utilize anticipated fuel-related cost savings and excess deferred income tax benefits in 2021 to offset the revenue requirement impacts of increasing electric and gas rate base, including the Kossuth wind farm, which was placed in service in October 2020, and the expansion of its gas distribution system in Western Wisconsin, which was placed in service in November 2020.
Planned Rate Review - WPL currently expects to file a retail electric and gas rate review with the PSCW in the second quarter of 2021 for either a single or multiple year forward-looking test period. The key drivers for the anticipated filing include lower excess deferred income tax benefits in 2022 and revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation. Any rate changes granted from this request are expected to be effective on January 1, 2022. WPL currently expects a decision from the PSCW regarding this rate filing by the end of 2021.
Rate Review Details - Details related to IPL’s and WPL’s key jurisdictions were as follows:

|  |  | Average |  | Authorized Return |  | Common Equity |  |
| Regulatory |  | Rate Base |  | on Common |  | Component of Regulatory |  | Effective
| Body |  | (in millions) |  | Equity (a) |  | Capital Structure |  | Date
IPL Retail Electric (2020 Test Period) |  |  |  |  |  |  |  |  |
Marshalltown (b) | IUB |  | $559 |  | 11.00% |  | 51.0% |  | 2/26/2020
Emery (b) | IUB |  | 165 |  | 12.23% |  | 51.0% |  | 2/26/2020
Whispering Willow - East (b) | IUB |  | 163 |  | 11.70% |  | 51.0% |  | 2/26/2020
Renewable energy rider (c) | IUB |  | 1,317 |  | 10.66% |  | 51.0% |  | 2/26/2020
Other (b) | IUB |  | 3,767 |  | 9.50% |  | 51.0% |  | 2/26/2020
IPL Retail Gas (2020 Test Period) (b) | IUB |  | 557 |  | 9.60% |  | 51.0% |  | 1/10/2020
IPL Wholesale Electric | FERC |  | 145 |  | 10.97% |  | 50.0% |  | 1/1/2020
WPL Retail Electric and Gas |  |  |  |  |  |  |  |  |
Electric (2021 Test Period) (d) | PSCW |  | 4,167 |  | 10.00% |  | 52.5% |  | 1/1/2021
Gas (2021 Test Period) (d) | PSCW |  | 481 |  | 10.00% |  | 52.5% |  | 1/1/2021
WPL Wholesale Electric | FERC |  | 296 |  | 10.90% |  | 55.0% |  | 1/1/2020

(a)Authorized returns on common equity may not be indicative of actual returns earned or projections of future returns.
(b)Average rate base amounts reflect IPL’s allocated retail share of rate base and do not include CWIP, and were calculated using a forecasted 13-month average for the test period.
(c)Average rate base amounts recovered through IPL’s renewable energy rider mechanism include construction costs incurred to fund IPL’s 1,000 MW of wind generation facilities placed in service in 2019 and 2020 (11.00% return on common equity), production tax credit carryforwards for the 1,000 MW of wind generation facilities (5.00% return on common equity) and certain transmission facilities classified as intangible assets (9.50% return on common equity), and were calculated using a 13-month average.
(d)Average rate base amounts reflect WPL’s allocated retail share of rate base and do not include CWIP or a cash working capital allowance, and were calculated using a forecasted 13-month average for the test period. The PSCW provides a return on selected CWIP and a cash working capital allowance by adjusting the percentage return on rate base.
Other Rate Matters
Federal Tax Reform - Federal Tax Reform resulted in future benefits to customers as a result of remeasurement of accumulated deferred income taxes (approximately $350 million for IPL and $460 million for WPL of retail revenue requirement). The majority of these benefits are subject to tax normalization rules (protected benefits), which limit the rate at which they can be passed on to their electric and gas customers.

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For those benefits that were not limited by tax normalization rules (the non-protected benefits), IPL began providing retail electric billing credits that will continue through June 2021, which include $27 million of excess deferred tax benefits. After returning these benefits to customers, IPL is not expected to have any significant remaining non-protected benefits as a result of the original Federal Tax Reform impacts.
WPL provided non-protected benefits back to its retail electric and gas customers in 2019 and 2020. In 2020, WPL utilized approximately $72 million to help maintain base rates at current levels and will utilize approximately $113 million to help maintain base rates at current levels through 2021. The remaining non-protected benefits of approximately $5 million will be addressed in WPL’s future retail electric and gas rate reviews.
LIQUIDITY AND CAPITAL RESOURCES
Overview - Alliant Energy, IPL and WPL expect to maintain adequate liquidity to operate their businesses and implement their strategy as a result of operating cash flows generated by their utility business, and available capacity under a single revolving credit facility and IPL’s sales of accounts receivable program, supplemented by periodic issuances of long-term debt and Alliant Energy equity securities. As summarized below, Alliant Energy, IPL and WPL believe they have the ability to generate and obtain adequate amounts of cash to meet their requirements and plans for cash in the next 12 months and beyond.
COVID-19 and Derecho Windstorm Considerations - Refer to “Overview” in MDA for discussion of COVID-19 and the derecho windstorm and the impacts on Alliant Energy’s, IPL’s and WPL’s liquidity and capital resources.
Liquidity Position - At December 31, 2020, Alliant Energy had $54 million of cash and cash equivalents, $611 million ($318 million at the parent company, $250 million at IPL and $43 million at WPL) of available capacity under the single revolving credit facility and $109 million of available capacity at IPL under its sales of accounts receivable program.
Capital Structure - Alliant Energy, IPL and WPL plan to maintain debt-to-total capitalization ratios that are consistent with investment-grade credit ratings. IPL and WPL expect to maintain capital structures consistent with their authorized levels. Capital structures as of December 31, 2020 were as follows (Common Equity (CE); IPL’s Preferred Stock (PS); Long-term Debt (including current maturities) (LD); Short-term Debt (SD)):
Alliant Energy, IPL and WPL intend to manage their capital structures and liquidity positions in such a way that facilitates their ability to raise funds reliably and on reasonable terms and conditions, while maintaining capital structures consistent with those approved by regulators. In addition to capital structures, other important factors used to determine the characteristics of future financings include financial coverage ratios, capital spending plans and solar construction that is expected to be financed by tax equity partners, regulatory orders and rate-making considerations, levels of debt imputed by rating agencies, market conditions, the impact of tax initiatives and legislation, and any potential proceeds from asset sales. The PSCW factors certain imputed debt adjustments in establishing a regulatory capital structure as part of WPL’s retail rate reviews. The IUB does not make any explicit adjustments for imputed debt in establishing capital ratios used in determining customer rates, although such adjustments are considered by IPL in recommending an appropriate capital structure. Debt imputations by rating agencies include, among others, pension and OPEB obligations and the sales of accounts receivable program.
Credit and Capital Markets - Alliant Energy, IPL and WPL maintain a single revolving credit facility to provide backstop liquidity to their commercial paper programs, and ensure a committed source of liquidity in the event the commercial paper market becomes disrupted. In addition, IPL maintains a sales of accounts receivable program as an alternative financing source; however, if customer arrears were to exceed certain levels, IPL’s access to the program may be restricted.
Primary Sources and Uses of Cash - Alliant Energy’s most significant source of cash is from electric and gas sales to IPL’s and WPL’s customers. Cash from these sales reimburses IPL and WPL for prudently-incurred expenses to provide service to their utility customers and generally provides IPL and WPL a return of and a return on the assets used to provide such services. Capital needed to retire debt and fund capital expenditures related to large strategic projects is expected to be met primarily through external financings.

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Cash Flows - Selected information from the cash flows statements was as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  |  | 2020 |  | 2019 |  |  | 2020 |  | 2019 |
Cash, cash equivalents and restricted cash, January 1 | $18 |  |  | $26 |  |  |  | $9 |  |  | $12 |  |  |  | $4 |  |  | $9 |  |
Cash flows from (used for): |  |  |  |  |  |  |  |  |  |  |  |  |  |
Operating activities | 501 |  |  | 660 |  |  |  | (6) |  |  | 173 |  |  |  | 466 |  |  | 423 |  |
Investing activities | (951) |  |  | (1,287) |  |  |  | (301) |  |  | (667) |  |  |  | (613) |  |  | (557) |  |
Financing activities | 488 |  |  | 619 |  |  |  | 348 |  |  | 491 |  |  |  | 146 |  |  | 129 |  |
Net increase (decrease) | 38 |  |  | (8) |  |  |  | 41 |  |  | (3) |  |  |  | (1) |  |  | (5) |  |
Cash, cash equivalents and restricted cash, December 31 | $56 |  |  | $18 |  |  |  | $50 |  |  | $9 |  |  |  | $3 |  |  | $4 |  |

Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for 2020 compared to 2019 (in millions):

| Alliant Energy |  | IPL |  | WPL
DAEC PPA amendment buyout payment in 2020 (Refer to Note 2) | ($110) |  | ($110) |  | $—
Amounts issued to IPL’s retail electric customers in 2020 through its transmission cost rider for amounts previously collected in rates (Refer to Note 2) | (42) |  | (42) |  | —
Timing of WPL’s fuel-related cost recoveries from customers | (38) |  | — |  | (38)
Decreased collections from IPL’s gas customers for energy efficiency amounts through the energy efficiency rider | (34) |  | (34) |  | —
Changes in cash collateral and deposit balances at Corporate Services | (24) |  | — |  | —
Decreased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales | (19) |  | (14) |  | (5)
Changes in income taxes paid/refunded | (16) |  | (25) |  | 42
Credits issued to IPL’s retail electric customers in 2020 through its tax benefit rider related to excess deferred income taxes amortization | (15) |  | (15) |  | —
Changes in interest payments | (6) |  | (19) |  | 1
Higher collections from IPL’s retail electric and gas base rate increases | 74 |  | 74 |  | —
Changes in levels of production fuel | 28 |  | 1 |  | 27
Refunds received in 2020 related to the MISO transmission owner return on equity complaint FERC orders (Refer to Note 1 7(g)) | 20 |  | 15 |  | 5
Other (primarily due to other changes in working capital) | 23 |  | (10) |  | 11
| ($159) |  | ($179) |  | $43

Income Tax Payments and Refunds - Income tax (payments) refunds, including refunds of alternative minimum tax credits, were as follows (in millions):

| 2020 |  | 2019 |  |
IPL | ($18) |  | $7 |  |
WPL | 13 |  | (29) |  |
Other subsidiaries | 10 |  | 43 |  |
Alliant Energy | $5 |  | $21 |  |

Alliant Energy, IPL and WPL currently do not expect to make any significant federal income tax payments through 2023 based on their current federal net operating loss and credit carryforward positions. While no significant federal income tax payments through 2023 are expected to occur, some tax payments and refunds may occur for state taxes and between consolidated group members (including IPL and WPL) under the tax sharing agreement between Alliant Energy and its subsidiaries. Refer to Note 12 for discussion of the carryforward positions.
Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $39 million, $17 million and $18 million of pension plan contributions in 2021, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2020 measurement date. Refer to Note 13(a) for discussion of the current funded levels of pension plans.

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Investing Activities - The following items contributed to increased (decreased) investing activity cash flows for 2020 compared to 2019 (in millions):

| Alliant Energy |  | IPL |  | WPL
Lower (higher) utility construction and acquisition expenditures (a) | $246 |  | $333 |  | ($87)
Changes in the amount of cash receipts on sold receivables | 45 |  | 45 |  | —
Refund from ATC in 2020 for construction deposits WPL previously provided to ATC for transmission network upgrades for West Riverside | 42 |  | — |  | 42
Expenditures for new acquisitions at AEF in 2019 | 13 |  | — |  | —
Other | (10) |  | (12) |  | (11)
| $336 |  | $366 |  | ($56)

(a)Largely due to lower expenditures for IPL’s expansion of wind generation, WPL’s West Riverside Energy Center and IPL’s advanced metering infrastructure, partially offset by higher expenditures for IPL’s and WPL’s electric and gas distribution systems (which include the derecho windstorm) and WPL’s expansion of wind generation.
Construction and Acquisition Expenditures - Construction and acquisition expenditures and financing plans are reviewed, approved and updated as part of the strategic planning process. Changes may result from a number of reasons, including regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, improvements in technology and improvements to ensure reliability of the electric and gas distribution systems. Alliant Energy, IPL and WPL have not yet entered into contractual commitments relating to the majority of their anticipated future construction and acquisition expenditures. As a result, they have some discretion with regard to the level and timing of these expenditures. The table below summarizes anticipated construction and acquisition expenditures (in millions). Cost estimates represent Alliant Energy’s, IPL’s and WPL’s portion of construction expenditures and exclude AFUDC and capitalized interest, if applicable. Such estimates do not reflect the assumption that a portion of the construction is expected to be financed by tax equity partners, which is described in more detail below in “IPL and WPL Solar Project Tax Equity Credits.” Refer to “Customer Investments” for further discussion of certain key projects impacting construction and acquisition plans related to the utility business.

| Alliant Energy |  | IPL |  | WPL
| 2021 | 2022 | 2023 | 2024 |  | 2021 | 2022 | 2023 | 2024 |  | 2021 | 2022 | 2023 | 2024
Generation: |  |  |  |  |  |  |  |  |  |  |  |  |  |
Renewable projects | $485 |  | $750 |  | $635 |  | $320 |  |  | $45 |  | $270 |  | $270 |  | $50 |  |  | $440 |  | $480 |  | $365 |  | $270 |
Other | 90 |  | 180 |  | 175 |  | 90 |  |  | 45 |  | 135 |  | 135 |  | 55 |  |  | 45 |  | 45 |  | 40 |  | 35 |
Distribution: |  |  |  |  |  |  |  |  |  |  |  |  |  |
Electric systems | 470 |  | 435 |  | 535 |  | 695 |  |  | 240 |  | 225 |  | 290 |  | 375 |  |  | 230 |  | 210 |  | 245 |  | 320 |
Gas systems | 70 |  | 75 |  | 70 |  | 70 |  |  | 35 |  | 40 |  | 30 |  | 30 |  |  | 35 |  | 35 |  | 40 |  | 40 |
Other | 180 |  | 185 |  | 190 |  | 195 |  |  | 10 |  | 10 |  | 10 |  | 25 |  |  | 15 |  | 10 |  | 10 |  | 10 |
| $1,295 |  | $1,625 |  | $1,605 |  | $1,370 |  |  | $375 |  | $680 |  | $735 |  | $535 |  |  | $765 |  | $780 |  | $700 |  | $675 |

West Riverside Options - WPL entered into agreements with neighboring utilities that provide them options to purchase a partial ownership interest in West Riverside. If such options are exercised, WPL will receive proceeds from the sale. Refer to “Customer Investments” for additional information, including the timing for the potential exercise of options.
Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for 2020 compared to 2019 (in millions):

| Alliant Energy |  | IPL |  | WPL
Lower (higher) payments to retire long-term debt | ($401) |  | ($200) |  | $100
Lower net proceeds from common stock issuances | (143) |  | — |  | —
Higher common stock dividends | (40) |  | (68) |  | (16)
Higher (lower) net proceeds from issuance of long-term debt | 300 |  | (200) |  | —
Net changes in the amount of commercial paper outstanding | 156 |  | 50 |  | 26
Higher (lower) capital contributions from IPL’s and WPL’s parent company, Alliant Energy | — |  | 279 |  | (100)
Other | (3) |  | (4) |  | 7
| ($131) |  | ($143) |  | $17

IPL and WPL Solar Project Tax Equity Credits - IPL and WPL each propose to own and operate their planned solar projects, which are currently expected to qualify for 30% investment tax credits, through a tax equity partnership, with approximately 35% to 45% of the construction costs financed with capital from the tax equity partner. This would allow IPL’s and WPL’s customers to share the costs of the solar projects with an investment partner for 10 years or less, while ensuring their customers receive energy, capacity, and renewable energy credit benefits from the projects. IPL and WPL would expect to purchase the tax equity partner’s interest in the solar projects within 10 years of operation, and then convert to a traditional

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ownership structure for the remainder of the useful life of the projects. Assuming a portion of the construction costs are financed by the tax equity partner, IPL would receive approximately $205 million from the tax equity partner in 2023, and WPL would receive approximately $210 million in 2022 and $275 million in 2023. IPL and WPL would expect to include their portion of capital expenditures, less the amounts financed by the tax equity partner, in their respective rate base.
FERC and Public Utility Holding Company Act Financing Authorizations - Under the Public Utility Holding Company Act of 2005, FERC has authority over the issuance of utility securities, except to the extent that a public utility’s primary state regulatory commission has retained jurisdiction over such matters. FERC currently has authority over the issuance of securities by IPL. FERC does not have authority over the issuance of securities by Alliant Energy, WPL, AEF or Corporate Services. In 2019, IPL received authorization from FERC to issue securities in 2020 and 2021 as follows (in millions):

| Initial Authorization |  | Remaining Capacity as of December 31, 2020
Long-term debt securities issuances in aggregate | $700 |  | $300
Short-term debt securities outstanding at any time (including borrowings from its parent) | 400 |  | 400
Preferred stock issuances in aggregate | 300 |  | 300

State Regulatory Financing Authorizations - In 2017, WPL received authorization from the PSCW to have up to $400 million of short-term borrowings and/or letters of credit outstanding at any time through the earlier of the expiration date of WPL’s credit facility agreement (including extensions) or December 2024. In September 2020, WPL received authorization from the PSCW to issue up to $1 billion of long-term debt securities in aggregate through December 2023.
Shelf Registrations - Alliant Energy, IPL and WPL have current shelf registration statements on file with the SEC for availability to issue unspecified amounts of securities through December 2023. Alliant Energy’s shelf registration statement may be used to issue common stock, debt and other securities. IPL’s and WPL’s shelf registration statements may be used to issue preferred stock and debt securities.
Common Stock Dividends - Payment of common stock dividends is subject to dividend declaration by Alliant Energy’s Board of Directors and is dependent upon, among other factors, regulatory limitations, earnings, cash flows, capital requirements and general financial condition of subsidiaries. Alliant Energy’s general long-term goal is to maintain a dividend payout ratio that is competitive with the industry average. Based on that, Alliant Energy’s goal is to maintain a dividend payout ratio of approximately 60% to 70% of consolidated earnings from continuing operations. Refer to “Results of Operations” for discussion of expected common stock dividends in 2021.
Common Stock Issuances - Refer to Note 7 for discussion of common stock issuances by Alliant Energy in 2019 and 2020, and “Results of Operations” for discussion of expected issuances of common stock in 2021.
Short-term Debt - In 2017, Alliant Energy, IPL and WPL entered into a single revolving credit facility agreement, which expires in August 2023 and is discussed in Note 9(a). There are currently 13 lenders that participate in the credit facility, with respective commitments ranging from $20 million to $130 million. Subject to certain conditions, Alliant Energy, IPL and WPL may exercise one extension option, extending the maturity date by one year. The credit facility has a provision to expand the facility size up to an additional $300 million, for a potential total commitment of $1.3 billion, subject to lender approval for Alliant Energy and subject to lender and regulatory approvals for IPL and WPL.
The credit agreement contains customary events of default, including a cross-default provision that would be triggered if Alliant Energy or certain of its significant subsidiaries (including IPL and WPL) defaults on debt (other than non-recourse debt) totaling $100 million or more. IPL and WPL are subject to a similar cross-default provision with respect to their own respective consolidated debt. A default by Alliant Energy or its non-utility subsidiaries would not trigger a cross-default at IPL or WPL, nor would a default by either of IPL or WPL constitute a cross-default event for the other. If an event of default under the credit agreement occurs and is continuing, then the lenders may declare any outstanding obligations of the defaulting borrower under the credit agreement immediately due and payable.
The single credit facility agreement contains a financial covenant, which requires Alliant Energy, IPL and WPL to maintain certain debt-to-capital ratios in order to borrow under the credit facility. AEF’s term loan credit agreement contains a financial covenant, which requires Alliant Energy to maintain a certain debt-to-capital ratio in order to borrow under the term loan credit agreement. The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2020 were as follows:

| Alliant Energy |  | IPL |  | WPL
Requirement, not to exceed | 65% |  | 65% |  | 65%
Actual | 55% |  | 46% |  | 50%

The debt component of the capital ratios includes, when applicable, long- and short-term debt (excluding non-recourse debt and hybrid securities to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), finance lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases. Unfunded vested benefits under qualified pension plans and sales of accounts receivable are not included in

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the debt-to-capital ratios. The equity component of the capital ratios excludes accumulated other comprehensive income (loss).
Long-term Debt - Refer to Note 9(b) for discussion of issuances and retirements of long-term debt in 2020 and “Results of Operations” for discussion of expected issuances of long-term debt in 2021. In 2019, IPL issued $300 million of 3.6% senior debentures (green bonds) due 2029 and $300 million of 3.5% senior debentures (green bonds) due 2049. In 2019, WPL issued $350 million of 3% debentures due 2029, and a portion of the proceeds from the issuance was used by WPL to refinance its $250 million 5% debentures that matured in 2019.
Impact of Credit Ratings on Liquidity and Collateral Obligations -
Ratings Triggers - The long-term debt of Alliant Energy and its subsidiaries is not subject to any repayment requirements as a result of explicit credit rating downgrades or so-called “ratings triggers.” However, Alliant Energy and its subsidiaries are parties to various agreements that contain provisions dependent on credit ratings. In the event of a significant downgrade, Alliant Energy or its subsidiaries may need to provide credit support, such as letters of credit or cash collateral equal to the amount of any exposure, or may need to unwind contracts or pay underlying obligations. In the event of a significant downgrade, management believes Alliant Energy, IPL and WPL have sufficient liquidity to cover counterparty credit support or collateral requirements under these various agreements. In addition, a downgrade in the credit ratings of Alliant Energy, IPL or WPL, could also result in them paying higher interest rates in future financings, reduce flexibility with future financing plans, reduce their pool of potential lenders, increase their borrowing costs under existing credit facilities or limit their access to the commercial paper market. Credit ratings and outlooks as of the date of this report are as follows:

|  | Standard & Poor’s Ratings Services |  | Moody’s Investors Service
Alliant Energy: | Corporate/issuer | A- |  | Baa2
| Commercial paper | A-2 |  | P-2
| Senior unsecured long-term debt | N/A |  | N/A
| Outlook | Stable |  | Stable
IPL: | Corporate/issuer | A- |  | Baa1
| Commercial paper | A-2 |  | P-2
| Senior unsecured long-term debt | A- |  | Baa1
| Preferred stock | BBB |  | Baa3
| Outlook | Stable |  | Stable
WPL: | Corporate/issuer | A |  | A3
| Commercial paper | A-1 |  | P-2
| Senior unsecured long-term debt | A |  | A3
| Outlook | Stable |  | Stable

Standard & Poor’s Ratings Services and Moody’s Investors Service issued credit ratings of BBB+ and Baa2, respectively, for the senior notes issued by AEF in 2018 and 2020 (with Alliant Energy as guarantor). Credit ratings are not recommendations to buy or sell securities and are subject to change, and each rating should be evaluated independently of any other rating. Each of Alliant Energy, IPL or WPL assumes no obligation to update their respective credit ratings. Refer to Note 15 for additional information on ratings triggers for commodity contracts accounted for as derivatives.
Off-Balance Sheet Arrangements -
Special Purpose Entities - IPL maintains a Receivables Agreement whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. The purchase commitment from the third party to which IPL sells its receivables expires in March 2021. IPL currently expects to amend and extend the purchase commitment. In 2020 and 2019, IPL evaluated the third party that purchases IPL’s receivable assets under the Receivables Agreement and believes that the third party is a VIE; however, IPL concluded consolidation of the third party was not required.
In addition, IPL’s sales of accounts receivable program agreement contains a cross-default provision that is triggered if IPL or Alliant Energy incurs an event of default on debt totaling $100 million or more. If an event of default under IPL’s sales of accounts receivable program agreement occurs, then the counterparty could terminate such agreement. Refer to Note 5(b) for additional information regarding IPL’s sales of accounts receivable program.
Guarantees and Indemnifications - At December 31, 2020, various guarantees and indemnifications are outstanding related to Alliant Energy’s cash equity ownership interest in a non-utility wind farm and prior divestiture activities. Refer to Note 17(d) for additional information.

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Certain Financial Commitments -
Contractual Obligations - Alliant Energy, IPL and WPL have various long-term contractual obligations as of December 31, 2020, which include long-term debt maturities in Note 9(b), operating and finance leases in Note 10, capital purchase obligations in Note 1 7(a), and other purchase obligations in Note 17(b). At December 31, 2020, Alliant Energy, IPL and WPL had no uncertain tax positions recorded as liabilities. Refer to Note 13(a) for anticipated pension and OPEB funding amounts, which are not included in the above tables. Refer to “Construction and Acquisition Expenditures” above for additional information on construction and acquisition programs. In addition, at December 31, 2020, there were various other liabilities included on the balance sheets that, due to the nature of the liabilities, the timing of payments cannot be estimated.
OTHER MATTERS
Market Risk Sensitive Instruments and Positions - Primary market risk exposures are associated with commodity prices, investment prices and interest rates. Risk management policies are used to monitor and assist in mitigating these market risks and derivative instruments are used to manage some of the exposures related to commodity prices. Refer to Notes 1(h) and 15 for further discussion of derivative instruments, and Note 1(g) for details of utility cost recovery mechanisms that significantly reduce commodity risk.
Commodity Price - Alliant Energy, IPL and WPL are exposed to the impact of market fluctuations in the price and transportation costs of commodities they procure and market. Established policies and procedures mitigate risks associated with these market fluctuations, including the use of various commodity derivatives and contracts of various durations for the forward sale and purchase of these commodities. Exposure to commodity price risks in the utility businesses is also significantly mitigated by current rate-making structures in place for recovery of fuel-related costs as well as the cost of natural gas purchased for resale. IPL’s electric and gas tariffs and WPL’s wholesale electric and gas tariffs provide for subsequent monthly adjustments to their tariff rates for material changes in prudently incurred commodity costs. IPL’s and WPL’s rate mechanisms, combined with commodity derivatives, significantly reduce commodity risk associated with their electric and gas margins. WPL’s retail electric margins have modest exposure to the impact of changes in commodity prices due largely to the current retail recovery mechanism in place in Wisconsin for fuel-related costs.
Investment Price - Alliant Energy, IPL and WPL are exposed to investment price risk as a result of their investments in securities, largely related to securities held by their pension and OPEB plans. Refer to Note 13(a) for details of the securities held by their pension and OPEB plans. Refer to “Critical Accounting Policies and Estimates” for the impact on retirement plan costs of changes in the rate of returns earned by plan assets.
Interest Rate - Alliant Energy, IPL and WPL are exposed to risk resulting from changes in interest rates associated with variable-rate borrowings. In addition, Alliant Energy and IPL are exposed to risk resulting from changes in interest rates on cash amounts outstanding under IPL’s sales of accounts receivable program. Assuming the impact of a hypothetical 100 basis point increase in interest rates on variable-rate borrowings and cash amounts outstanding under IPL’s sales of accounts receivable program at December 31, 2020, Alliant Energy’s, IPL’s and WPL’s annual pre-tax expense would increase by approximately $7 million, $0 and $3 million, respectively. Refer to Notes 5(b) and 9 for additional information on cash amounts outstanding under IPL’s sales of accounts receivable program, and short- and long-term variable-rate borrowings, respectively. Refer to “Critical Accounting Policies and Estimates” for the impacts of changes in discount rates on retirement plan obligations and costs.
New Accounting Standards - Refer to Note 1(o) for discussion of new accounting standards impacting Alliant Energy, IPL and WPL.
Critical Accounting Policies and Estimates - Alliant Energy’s, IPL’s and WPL’s financial statements are prepared in conformity with GAAP, which requires management to apply accounting policies, judgments and assumptions, and make estimates that affect results of operations and the amounts of assets and liabilities reported in the financial statements. The following accounting policies and estimates are critical to the business and the understanding of financial results as they require critical assumptions and judgments by management. The results of these assumptions and judgments form the basis for making estimates regarding the results of operations and the amounts of assets and liabilities that are not readily apparent from other sources. Actual financial results may differ materially from estimates. Management has discussed these critical accounting policies and estimates with the Audit Committee of the Board of Directors. Refer to Note 1 for additional discussion of accounting policies and estimates used in the preparation of the financial statements.
Regulatory Assets and Regulatory Liabilities - IPL and WPL are regulated by various federal and state regulatory agencies. As a result, they are subject to GAAP for regulated operations, which recognizes that the actions of a regulator can provide reasonable assurance of the existence of an asset or liability. Regulatory assets or regulatory liabilities arise as a result of a difference between GAAP and actions imposed by the regulatory agencies in the rate-making process. Regulatory assets generally represent incurred costs that have been deferred as such costs are probable of recovery in future customer rates. Regulatory liabilities generally represent obligations to make refunds to customers or amounts collected in rates for which the related costs have not yet been incurred. Regulatory assets and regulatory liabilities are recognized in accordance with the rulings of applicable federal and state regulators, and future regulatory rulings may impact the carrying value and accounting treatment of regulatory assets and regulatory liabilities.

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Assumptions and judgments are made each reporting period regarding whether regulatory assets are probable of future recovery and regulatory liabilities are probable future obligations by considering factors such as regulatory environment changes, rate orders issued by the applicable regulatory agencies, historical decisions by such regulatory agencies regarding similar regulatory assets and regulatory liabilities, and subsequent events of such regulatory agencies. The decisions made by regulatory authorities have an impact on the recovery of costs, the rate of return on invested capital and the timing and amount of assets to be recovered by rates. A change in these decisions may result in a material impact on results of operations and the amount of assets and liabilities in the financial statements. Note 2 provides details of the nature and amounts of regulatory assets and regulatory liabilities assessed at December 31, 2020.
Income Taxes - Alliant Energy, IPL and WPL are subject to income taxes in various jurisdictions. Assumptions and judgments are made each reporting period to estimate income tax assets, liabilities, benefits and expenses. Judgments and assumptions are supported by historical data and reasonable projections. Significant changes in these judgments and assumptions could have a material impact on financial condition and results of operations. Alliant Energy’s and IPL’s critical assumptions and judgments for 2020 include estimates of qualifying deductions for repairs expenditures and allocation of mixed service costs due to the impact of Iowa rate-making principles on such property-related differences. Critical assumptions and judgments also include projections of future taxable income used to determine the ability to utilize net operating losses and credit carryforwards prior to their expiration. Refer to Note 12 for further discussion of tax matters.
Effect of Rate-making on Property-related Differences - Alliant Energy’s and IPL’s effective income tax rates are normally impacted by certain property-related differences at IPL for which deferred tax is not recorded in the income statement pursuant to Iowa rate-making principles. Changes in methods or assumptions regarding the amount of IPL’s qualifying repairs expenditures, allocation of mixed service costs, and costs related to retirement or removal of depreciable property could result in a material impact on Alliant Energy’s and IPL’s financial condition and results of operations.
Carryforward Utilization - Significant federal tax credit carryforwards and federal and state net operating loss carryforwards exist for Alliant Energy, IPL and WPL as of December 31, 2020. Based on projections of current and future taxable income, Alliant Energy, IPL and WPL plan to utilize substantially all of these carryforwards prior to their expiration. Taxable income must be reduced by federal net operating losses carryforwards prior to utilizing federal tax credit carryforwards. Alliant Energy does not expect to utilize all of its federal net operating loss carryforwards until 2023, and therefore, currently does not expect to utilize 2002 vintage federal credit carryforwards prior to their expiration in 2022, resulting in valuation allowances that remain as of December 31, 2020. Refer to Note 12 for discussion of expected utilization of 2003 vintage federal credit carryforwards prior to their expiration in 2023, which resulted in the reversal of previously recorded valuation allowances in 2020. Federal credit carryforwards generated from 2003 through 2009, which amount to $17 million for Alliant Energy, are expected to be utilized within five years of expiration. All other federal credit carryforwards and federal net operating loss carryforwards are expected to be utilized more than five years before expiration. Changes in tax regulations or assumptions regarding current and future taxable income could require changes to valuation allowances in the future resulting in a material impact on financial condition and results of operations.
Long-Lived Assets - Periodic assessments regarding the recoverability of certain long-lived assets are completed when factors indicate the carrying value of such assets may not be recoverable or such assets are planned to be sold. These assessments require significant assumptions and judgments by management. The long-lived assets assessed for impairment generally include certain assets within regulated operations that may not be fully recovered from IPL’s and WPL’s customers as a result of regulatory decisions in the future, and assets within non-utility operations that are proposed to be sold or are currently generating operating losses.
Regulated Operations - Alliant Energy’s, IPL’s and WPL’s long-lived assets within their regulated operations that were assessed for impairment and plant abandonment in 2020 included IPL’s and WPL’s generating units subject to early retirement.
Generating Units Subject to Early Retirement - Alliant Energy, IPL and WPL evaluate future plans for their electric generation fleet and have announced the early retirement of certain older and less-efficient EGUs. When it becomes probable that an EGU will be retired before the end of its useful life, Alliant Energy, IPL and WPL must assess whether the EGU meets the criteria to be considered probable of abandonment. EGUs that are considered probable of abandonment generally have material remaining net book values and are expected to cease operations in the near term significantly before the end of their original estimated useful lives. If an EGU meets such criteria to be considered probable of abandonment, Alliant Energy, IPL and WPL must assess the probability of full recovery of the remaining carrying value of such EGU. If it is probable that regulators will not allow full recovery of and a full return on the remaining net book value of the abandoned EGU, an impairment charge is recognized equal to the difference between the remaining carrying value and the present value of the future revenues expected from the abandoned EGU.
Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5, met the criteria to be considered probable of abandonment in 2020. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGU from both its retail and wholesale customers, and as a result, Alliant Energy, IPL and WPL concluded that no impairment was required as of December 31, 2020. Alliant Energy, IPL and WPL evaluated their other EGUs that are subject to early retirement and determined that no other EGUs met the criteria to be considered probable of abandonment as of December 31, 2020. Note 3 provides additional details of these assets anticipated to be retired early.

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Unbilled Revenues - Unbilled revenues are primarily associated with utility operations. Energy sales to individual customers are based on the reading of customers’ meters, which occurs on a systematic basis throughout the month. Amounts of energy delivered to customers since the date of the last meter reading are estimated at the end of each reporting period and the corresponding estimated unbilled revenue is recorded. The unbilled revenue is based on estimates of daily system demand volumes, customer usage by class, temperature impacts, line losses and the most recent customer rates. Such process involves the use of various judgments and assumptions and significant changes in these judgments and assumptions could have a material impact on results of operations. As of December 31, 2020, unbilled revenues related to Alliant Energy’s utility operations were $174 million ($92 million at IPL and $82 million at WPL).
Pensions and Other Postretirement Benefits - Alliant Energy, IPL and WPL sponsor various defined benefit pension and OPEB plans that provide benefits to a significant portion of their employees and retirees. Assumptions and judgments are made periodically to estimate the obligations and costs related to their retirement plans. There are many judgments and assumptions involved in determining an entity’s pension and other postretirement liabilities and costs each period including employee demographics (including life expectancies and compensation levels), discount rates, assumed rates of return and funding. Changes made to plan provisions may also impact current and future benefits costs. Judgments and assumptions are supported by historical data and reasonable projections and are reviewed at least annually. The following table shows the impacts of changing certain key actuarial assumptions discussed above (in millions):

|  | Defined Benefit Pension Plans |  | OPEB Plans
Change in Actuarial Assumption |  | Impact on Projected Benefit Obligation at December 31, 2020 |  | Impact on 2021 Net Periodic Benefit Costs |  | Impact on Accumulated Benefit Obligation at December 31, 2020 |  | Impact on 2021 Net Periodic Benefit Costs
Alliant Energy |  |  |  |  |  |  |  |
1% change in discount rate |  | $183 |  | $11 |  | $22 |  | $2
1% change in expected rate of return |  | N/A |  | 10 |  | N/A |  | 1
IPL |  |  |  |  |  |  |  |
1% change in discount rate |  | 86 |  | 6 |  | 8 |  | 1
1% change in expected rate of return |  | N/A |  | 4 |  | N/A |  | 1
WPL |  |  |  |  |  |  |  |
1% change in discount rate |  | 81 |  | 5 |  | 8 |  | 1
1% change in expected rate of return |  | N/A |  | 4 |  | N/A |  | —

Contingencies - Assumptions and judgments are made each reporting period regarding the future outcome of contingent events. Loss contingency amounts are recorded for any contingent events for which the likelihood of loss is probable and able to be reasonably estimated based upon current available information. The amounts recorded may differ from actuals when the uncertainty is resolved. The estimates made in accounting for contingencies, and the gains and losses that are recorded upon the ultimate resolution of these uncertainties, could have a significant effect on results of operations and the amount of assets and liabilities in the financial statements.
Effective January 1, 2020 upon the adoption of the new accounting standard for credit losses, certain contingencies, such as Alliant Energy Resources, LLC’s guarantees of the partnership obligations of an affiliate of Whiting Petroleum, require estimation each reporting period of the expected credit losses on those contingencies. These estimates require significant judgment and result in recognition of a credit loss liability sooner than the previous accounting standards, which required recognition when the contingency became probable and could be reasonably estimated based on then currently available information. With respect to Alliant Energy’s guarantees of the partnership obligations of an affiliate of Whiting Petroleum, the most significant judgments in determining the credit loss liability were the estimate of the exposure under the guarantees and the methodology used for calculating the credit loss liability. As of December 31, 2020, Alliant Energy currently estimates the exposure to be a portion of the known partnership abandonment obligations. The methodology used to determine the credit loss liability considers both quantitative and qualitative information, which utilizes potential outcomes in a range of possible estimated amounts. Factors considered include market and external data points, the creditworthiness of the other partners, Whiting Petroleum’s emergence from bankruptcy in the third quarter of 2020, and forecasted cash flow expenditures associated with the abandonment obligations based on information made available to Alliant Energy. Note 1(o) provides discussion of the adoption of the new accounting standard for credit losses.
Note 17 provides further discussion of contingencies assessed at December 31, 2020 that may have a material impact on financial condition and results of operations, including impacts to Alliant Energy’s ATC Holdings equity earnings as a result of future changes in FERC’s evaluation of certain MISO return on equity complaints, various pending legal proceedings, guarantees and indemnifications.
ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
Quantitative and Qualitative Disclosures About Market Risk are reported in “Other Matters - Market Risk Sensitive Instruments and Positions” in MDA.
ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
To the Shareowners and the Board of Directors of Alliant Energy Corporation:
Opinion on the Financial Statements
We have audited the accompanying consolidated balance sheets of Alliant Energy Corporation and subsidiaries (the “Company”) as of December 31, 2020 and 2019, the related consolidated statements of income, equity, and cash flows, for each of the three years in the period ended December 31, 2020, and the related notes and the schedules listed in the Index at Item 15 (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2020 and 2019, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2020, in conformity with accounting principles generally accepted in the United States of America.
We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company’s internal control over financial reporting as of December 31, 2020, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated February 19, 2021, expressed an unqualified opinion on the Company’s internal control over financial reporting.
Basis for Opinion
These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.
Critical Audit Matter
The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.
Regulatory Assets and Regulatory Liabilities - Impact of rate regulation on the financial statements - Refer to Notes 1 and 2 to the financial statements
Critical Audit Matter Description
Alliant Energy Corporation, through its wholly owned subsidiaries, Interstate Power and Light Company and Wisconsin Power and Light Company is subject to rate regulation by the Federal Energy Regulatory Commission and the respective state commissions in Iowa and Wisconsin (collectively, the “regulatory agencies”). Management has determined it meets the requirements under accounting principles generally accepted in the United States of America to prepare its financial statements applying the Regulated Operations Topic 980 of the Financial Accounting Standards Board’s Accounting Standards Codification. As of December 31, 2020, the Company had a recorded consolidated regulatory assets balance of $2,010 million and regulatory liabilities balance of $1,306 million.

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The Company’s rates are subject to regulatory rate-setting processes and annual earnings oversight. The regulation of rates is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital. Regulatory assets represent incurred costs that have been deferred and are probable of recovery in future customer rates. Regulatory liabilities represent obligations to make refunds to customers or amounts collected in rates for which the costs have not yet been incurred. The Company’s regulatory assets and regulatory liabilities are recognized in accordance with the rulings of the regulatory agencies. A change in these rulings may result in a material impact on results of operations and the amount of assets and liabilities in the financial statements. Future regulatory rulings may impact the carrying value and accounting treatment of the regulatory assets and regulatory liabilities.
We identified the impact of rate regulation as a critical audit matter due to the significant judgments made by management to support its assertions about impacted account balances and disclosures and the high degree of subjectivity involved in assessing the impact of future regulatory orders on the financial statements. Management judgments include assessing the likelihood of the recovery of incurred costs and refund of obligations to customers in future rates. Given that management’s accounting judgments are based on assumptions about the outcome of future decisions by the regulatory agencies, auditing these judgments required specialized knowledge of accounting for rate regulation and the rate-setting process due to its inherent complexities.
How the Critical Audit Matter Was Addressed in the Audit
Our audit procedures related to the regulatory filings by management and the uncertainty of future decisions by the regulatory agencies included the following, among others:
•We tested the design and operating effectiveness of management’s controls over the evaluation of regulatory assets and liabilities, including the monitoring and evaluation of regulatory developments that may affect the likelihood of recovering costs in future rates or of a future reduction in rates.
•We inspected the Company’s analysis supporting the probability of recovery for regulatory assets or refund or future reduction in rates for regulatory liabilities not yet addressed in a regulatory order to assess the reasonability of management’s assertions.
•We inquired of management regarding current events impacting the Company and inspected minutes of the board of directors and other committees of the Company and evaluated whether matters were identified that may have an impact on recorded regulatory asset and liability balances.
•We read relevant regulatory orders, regulatory statutes, interpretations, procedural memorandums, filings made by interveners, and other publicly available information issued by the regulatory agencies that pertain to the Company as well as to other relevant public utilities. We evaluated the external information and assessed whether there were matters in such information that would be contradictory to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.
•We obtained representation letters from management and evaluated such letters to assess whether information was present that would be relevant to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.
•We evaluated the Company’s disclosures related to the impacts of rate regulation and regulatory developments, including disclosures related to the regulatory balances recorded.
/s/ DELOITTE & TOUCHE LLP
Milwaukee, Wisconsin
February 19, 2021
We have served as the Company’s auditor since 2002.

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ALLIANT ENERGY CORPORATION
CONSOLIDATED STATEMENTS OF INCOME

| Year Ended December 31,
| 2020 |  | 2019 |  | 2018
| (in millions, except per share amounts)
Revenues: |  |  |  |  |
Electric utility | $2,920 |  |  | $3,064 |  |  | $3,000 |
Gas utility | 373 |  |  | 455 |  |  | 447 |
Other utility | 49 |  |  | 46 |  |  | 48 |
Non-utility | 74 |  |  | 83 |  |  | 39 |
Total revenues | 3,416 |  |  | 3,648 |  |  | 3,534 |
Operating expenses: |  |  |  |  |
Electric production fuel and purchased power | 652 |  |  | 777 |  |  | 855 |
Electric transmission service | 449 |  |  | 481 |  |  | 496 |
Cost of gas sold | 182 |  |  | 222 |  |  | 232 |
Other operation and maintenance | 670 |  |  | 712 |  |  | 646 |
Depreciation and amortization | 615 |  |  | 567 |  |  | 507 |
Taxes other than income taxes | 108 |  |  | 111 |  |  | 104 |
Total operating expenses | 2,676 |  |  | 2,870 |  |  | 2,840 |
Operating income | 740 |  |  | 778 |  |  | 694 |
Other (income) and deductions: |  |  |  |  |
Interest expense | 275 |  |  | 273 |  |  | 247 |
Equity income from unconsolidated investments, net | (61) |  |  | (53) |  |  | (55) |
Allowance for funds used during construction | (55) |  |  | (93) |  |  | (76) |
Other | 14 |  |  | 15 |  |  | 8 |
Total other (income) and deductions | 173 |  |  | 142 |  |  | 124 |
Income before income taxes | 567 |  |  | 636 |  |  | 570 |
Income tax expense (benefit) | (57) |  |  | 69 |  |  | 48 |
Net income | 624 |  |  | 567 |  |  | 522 |
Preferred dividend requirements of Interstate Power and Light Company | 10 |  |  | 10 |  |  | 10 |
Net income attributable to Alliant Energy common shareowners | $614 |  |  | $557 |  |  | $512 |
Weighted average number of common shares outstanding: |  |  |  |  |
Basic | 248.4 |  |  | 238.5 |  |  | 233.6 |
Diluted | 248.7 |  |  | 239.0 |  |  | 233.6 |
Earnings per weighted average common share attributable to Alliant Energy common shareowners: |  |  |  |  |
Basic | $2.47 |  |  | $2.34 |  |  | $2.19 |
Diluted | $2.47 |  |  | $2.33 |  |  | $2.19 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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Table of Cont ents
ALLIANT ENERGY CORPORATION
CONSOLIDATED BALANCE SHEETS

| December 31,
| 2020 |  | 2019
| (in millions, except per share and share amounts)
ASSETS |  |  |
Current assets: |  |  |
Cash and cash equivalents | $54 |  |  | $16 |
Accounts receivable, less allowance for expected credit losses | 412 |  |  | 402 |
Production fuel, at weighted average cost | 66 |  |  | 78 |
Gas stored underground, at weighted average cost | 46 |  |  | 49 |
Materials and supplies, at weighted average cost | 105 |  |  | 100 |
Regulatory assets | 81 |  |  | 87 |
Other | 123 |  |  | 144 |
Total current assets | 887 |  |  | 876 |
Property, plant and equipment, net | 14,336 |  |  | 13,527 |
Investments: |  |  |
ATC Holdings | 331 |  |  | 320 |
Other | 154 |  |  | 148 |
Total investments | 485 |  |  | 468 |
Other assets: |  |  |
Regulatory assets | 1,929 |  |  | 1,758 |
Deferred charges and other | 73 |  |  | 72 |
Total other assets | 2,002 |  |  | 1,830 |
Total assets | $17,710 |  |  | $16,701 |

LIABILITIES AND EQUITY |  |  |
Current liabilities: |  |  |
Current maturities of long-term debt | $8 |  |  | $657 |
Commercial paper | 389 |  |  | 337 |
Accounts payable | 377 |  |  | 422 |
Accrued taxes | 67 |  |  | 70 |
Regulatory liabilities | 249 |  |  | 212 |
Other | 207 |  |  | 356 |
Total current liabilities | 1,297 |  |  | 2,054 |
Long-term debt, net (excluding current portion) | 6,769 |  |  | 5,533 |
Other liabilities: |  |  |
Deferred tax liabilities | 1,814 |  |  | 1,714 |
Regulatory liabilities | 1,057 |  |  | 1,212 |
Pension and other benefit obligations | 511 |  |  | 484 |
Other | 374 |  |  | 299 |
Total other liabilities | 3,756 |  |  | 3,709 |
Commitments and contingencies (Note 17) |  |  |
Equity: |  |  |
Alliant Energy Corporation common equity: |  |  |
Common stock - $0.01 par value - 480,000,000 shares authorized; 249,868,415 and 245,022,800 shares outstanding | 2 |  |  | 2 |
Additional paid-in capital | 2,704 |  |  | 2,446 |
Retained earnings | 2,994 |  |  | 2,766 |
Accumulated other comprehensive income (loss) | (1) |  |  | 1 |
Shares in deferred compensation trust - 380,542 and 381,232 shares at a weighted average cost of $28.73 and $26.24 per share | (11) |  |  | (10) |
Total Alliant Energy Corporation common equity | 5,688 |  |  | 5,205 |
Cumulative preferred stock of Interstate Power and Light Company | 200 |  |  | 200 |
Total equity | 5,888 |  |  | 5,405 |
Total liabilities and equity | $17,710 |  |  | $16,701 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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Table of Cont ents
ALLIANT ENERGY CORPORATION
CONSOLIDATED STATEMENTS OF CASH FLOWS

| Year Ended December 31,
| 2020 |  | 2019 |  | 2018
| (in millions)
Cash flows from operating activities: |  |  |  |  |
Net income | $624 |  |  | $567 |  |  | $522 |
Adjustments to reconcile net income to net cash flows from operating activities: |  |  |  |  |
Depreciation and amortization | 615 |  |  | 567 |  |  | 507 |
Deferred tax expense (benefit) and tax credits | (66) |  |  | 56 |  |  | 67 |
Equity component of allowance for funds used during construction | (39) |  |  | (66) |  |  | (51) |
Other | 37 |  |  | 20 |  |  | 8 |
Other changes in assets and liabilities: |  |  |  |  |
Accounts receivable | (468) |  |  | (472) |  |  | (475) |
Regulatory assets | (130) |  |  | (16) |  |  | (16) |
Regulatory liabilities | (113) |  |  | (40) |  |  | 1 |
Deferred income taxes | 171 |  |  | 54 |  |  | 56 |
DAEC PPA amendment buyout payment | (110) |  |  | — |  |  | — |
Other | (20) |  |  | (10) |  |  | (91) |
Net cash flows from operating activities | 501 |  |  | 660 |  |  | 528 |
Cash flows used for investing activities: |  |  |  |  |
Construction and acquisition expenditures: |  |  |  |  |
Utility business | (1,293) |  |  | (1,539) |  |  | (1,569) |
Other | (73) |  |  | (101) |  |  | (65) |
Cash receipts on sold receivables | 458 |  |  | 413 |  |  | 605 |
Other | (43) |  |  | (60) |  |  | (38) |
Net cash flows used for investing activities | (951) |  |  | (1,287) |  |  | (1,067) |
Cash flows from financing activities: |  |  |  |  |
Common stock dividends | (377) |  |  | (337) |  |  | (312) |
Proceeds from issuance of common stock, net | 247 |  |  | 390 |  |  | 197 |
Proceeds from issuance of long-term debt | 1,250 |  |  | 950 |  |  | 1,500 |
Payments to retire long-term debt | (657) |  |  | (256) |  |  | (856) |
Net change in commercial paper and other short-term borrowings | 52 |  |  | (104) |  |  | 26 |
Other | (27) |  |  | (24) |  |  | (24) |
Net cash flows from financing activities | 488 |  |  | 619 |  |  | 531 |
Net increase (decrease) in cash, cash equivalents and restricted cash | 38 |  |  | (8) |  |  | (8) |
Cash, cash equivalents and restricted cash at beginning of period | 18 |  |  | 26 |  |  | 34 |
Cash, cash equivalents and restricted cash at end of period | $56 |  |  | $18 |  |  | $26 |
Supplemental cash flows information: |  |  |  |  |
Cash (paid) refunded during the period for: |  |  |  |  |
Interest | ($274) |  |  | ($268) |  |  | ($247) |
Income taxes, net | $5 |  |  | $21 |  |  | ($5) |
Significant non-cash investing and financing activities: |  |  |  |  |
Accrued capital expenditures | $131 |  |  | $196 |  |  | $299 |
Beneficial interest obtained in exchange for securitized accounts receivable | $188 |  |  | $188 |  |  | $119 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION
CONSOLIDATED STATEMENTS OF EQUITY

| Total Alliant Energy Common Equity |  |  |  |
|  |  |  |  |  |  | Accumulated |  | Shares in |  | Cumulative |  |
|  |  | Additional |  |  |  | Other |  | Deferred |  | Preferred |  |
| Common |  | Paid-In |  | Retained |  | Comprehensive |  | Compensation |  | Stock |  | Total
| Stock |  | Capital |  | Earnings |  | Income (Loss) |  | Trust |  | of IPL |  | Equity
| (in millions)
2018: |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance | $2 |  | $1,845 |  | $2,346 |  | $— |  | ($11) |  | $200 |  |  | $4,382 |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 512 |  |  |  |  |  |  |  |  | 512 |
Common stock dividends ($1.34 per share) |  |  |  |  | (312) |  |  |  |  |  |  |  |  | (312) |
At-the-market offering program and Shareowner Direct Plan issuances |  |  | 197 |  |  |  |  |  |  |  |  |  |  | 197 |
Equity-based compensation plans and other |  |  | 4 |  |  |  |  |  |  | 1 |  |  |  | 5 |
Other comprehensive income, net of tax |  |  |  |  |  |  | 2 |  |  |  |  |  | 2 |
Ending balance | 2 |  | 2,046 |  |  | 2,546 |  |  | 2 |  | (10) |  | 200 |  |  | 4,786 |
2019: |  |  |  |  |  |  |  |  |  |  |  |  |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 557 |  |  |  |  |  |  |  |  | 557 |
Common stock dividends ($1.42 per share) |  |  |  |  | (337) |  |  |  |  |  |  |  |  | (337) |
Equity forward settlements and Shareowner Direct Plan issuances |  |  | 390 |  |  |  |  |  |  |  |  |  |  | 390 |
Equity-based compensation plans and other |  |  | 10 |  |  |  |  |  |  |  |  |  |  | 10 |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (1) |  |  |  |  |  | (1) |
Ending balance | 2 |  | 2,446 |  |  | 2,766 |  |  | 1 |  | (10) |  | 200 |  |  | 5,405 |
2020: |  |  |  |  |  |  |  |  |  |  |  |  |
Net income attributable to Alliant Energy common shareowners |  |  |  |  | 614 |  |  |  |  |  |  |  |  | 614 |
Common stock dividends ($1.52 per share) |  |  |  |  | (377) |  |  |  |  |  |  |  |  | (377) |
Equity forward settlements and Shareowner Direct Plan issuances |  |  | 247 |  |  |  |  |  |  |  |  |  |  | 247 |
Equity-based compensation plans and other |  |  | 11 |  |  |  |  |  |  | (1) |  |  |  | 10 |
Adoption of new accounting standard, net of tax (refer to Note 1(o)) |  |  |  |  | (9) |  |  |  |  |  |  |  |  | (9) |
Other comprehensive loss, net of tax |  |  |  |  |  |  | (2) |  |  |  |  |  | (2) |
Ending balance | $2 |  | $2,704 |  |  | $2,994 |  |  | ($1) |  | ($11) |  | $200 |  |  | $5,888 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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Table of Cont ents
REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
To the Shareowners and the Board of Directors of Interstate Power and Light Company:
Opinion on the Financial Statements
We have audited the accompanying consolidated balance sheets of Interstate Power and Light Company and subsidiary (the “Company”) as of December 31, 2020 and 2019, the related consolidated statements of income, equity, and cash flows, for each of the three years in the period ended December 31, 2020, and the related notes and the schedule listed in the Index at Item 15 (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2020 and 2019, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2020, in conformity with accounting principles generally accepted in the United States of America.
Basis for Opinion
These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.
Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.
Critical Audit Matter
The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.
Regulatory Assets and Regulatory Liabilities - Impact of rate regulation on the financial statements - Refer to Notes 1 and 2 to the financial statements
Critical Audit Matter Description
Interstate Power and Light Company is subject to rate regulation by the Federal Energy Regulatory Commission and state commission in Iowa (collectively, the “regulatory agencies”). Management has determined it meets the requirements under accounting principles generally accepted in the United States of America to prepare its financial statements applying the Regulated Operations Topic 980 of the Financial Accounting Standards Board’s Accounting Standards Codification. As of December 31, 2020, the Company had a recorded consolidated regulatory assets balance of $1,483 million and regulatory liabilities balance of $676 million.
The Company’s rates are subject to regulatory rate-setting processes and annual earnings oversight. The regulation of rates is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital. Regulatory assets represent incurred costs that have been deferred and are probable of recovery in future customer rates. Regulatory liabilities represent obligations to make refunds to customers or amounts collected in rates for which the costs have not yet been incurred. The Company’s regulatory assets and regulatory liabilities are recognized in accordance with the rulings of the regulatory agencies. A change in these rulings may result in a material impact on results of operations and the amount of assets and liabilities in the financial statements. Future regulatory rulings may impact the carrying value and accounting treatment of the regulatory assets and regulatory liabilities.

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Table of Cont ents
We identified the impact of rate regulation as a critical audit matter due to the significant judgments made by management to support its assertions about impacted account balances and disclosures and the high degree of subjectivity involved in assessing the impact of future regulatory orders on the financial statements. Management judgments include assessing the likelihood of the recovery of incurred costs and refund of obligations to customers in future rates. Given that management’s accounting judgments are based on assumptions about the outcome of future decisions by the regulatory agencies, auditing these judgments required specialized knowledge of accounting for rate regulation and the rate-setting process due to its inherent complexities.
How the Critical Audit Matter Was Addressed in the Audit
Our audit procedures related to the regulatory filings by management and the uncertainty of future decisions by the regulatory agencies included the following, among others:
•We tested the design and operating effectiveness of management’s controls over the evaluation of regulatory assets and liabilities, including the monitoring and evaluation of regulatory developments that may affect the likelihood of recovering costs in future rates or of a future reduction in rates.
•We inspected the Company’s analysis supporting the probability of recovery for regulatory assets or refund or future reduction in rates for regulatory liabilities not yet addressed in a regulatory order to assess the reasonability of management’s assertions.
•We inquired of management regarding current events impacting the Company and inspected minutes of the board of directors and other committees of the Company and evaluated whether matters were identified that may have an impact on recorded regulatory asset and liability balances.
•We read relevant regulatory orders, regulatory statutes, interpretations, procedural memorandums, filings made by interveners, and other publicly available information issued by the regulatory agencies that pertain to the Company as well as to other relevant public utilities. We evaluated the external information and assessed whether there were matters in such information that would be contradictory to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.
•We obtained representation letters from management and evaluated such letters to assess whether information was present that would be relevant to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.
•We evaluated the Company’s disclosures related to the impacts of rate regulation and regulatory developments, including disclosures related to the regulatory balances recorded.
/s/ DELOITTE & TOUCHE LLP
Milwaukee, Wisconsin
February 19, 2021
We have served as the Company’s auditor since 2002.

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Table of Cont ents
INTERSTATE POWER AND LIGHT COMPANY
CONSOLIDATED STATEMENTS OF INCOME

| Year Ended December 31,
| 2020 |  | 2019 |  | 2018
| (in millions)
Revenues: |  |  |  |  |
Electric utility | $1,695 |  |  | $1,781 |  |  | $1,731 |
Gas utility | 208 |  |  | 264 |  |  | 266 |
Steam and other | 44 |  |  | 44 |  |  | 45 |
Total revenues | 1,947 |  |  | 2,089 |  |  | 2,042 |
Operating expenses: |  |  |  |  |
Electric production fuel and purchased power | 352 |  |  | 435 |  |  | 469 |
Electric transmission service | 298 |  |  | 340 |  |  | 353 |
Cost of gas sold | 99 |  |  | 120 |  |  | 129 |
Other operation and maintenance | 375 |  |  | 404 |  |  | 403 |
Depreciation and amortization | 356 |  |  | 327 |  |  | 283 |
Taxes other than income taxes | 57 |  |  | 60 |  |  | 54 |
Total operating expenses | 1,537 |  |  | 1,686 |  |  | 1,691 |
Operating income | 410 |  |  | 403 |  |  | 351 |
Other (income) and deductions: |  |  |  |  |
Interest expense | 139 |  |  | 127 |  |  | 119 |
Allowance for funds used during construction | (24) |  |  | (50) |  |  | (42) |
Other | 8 |  |  | 8 |  |  | 3 |
Total other (income) and deductions | 123 |  |  | 85 |  |  | 80 |
Income before income taxes | 287 |  |  | 318 |  |  | 271 |
Income tax expense (benefit) | (47) |  |  | 24 |  |  | (3) |
Net income | 334 |  |  | 294 |  |  | 274 |
Preferred dividend requirements | 10 |  |  | 10 |  |  | 10 |
Net income available for common stock | $324 |  |  | $284 |  |  | $264 |

Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of IPL’s common stock outstanding during the periods presented.
Refer to accompanying Combined Notes to Consolidated Financial Statements.

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Table of Cont ents
INTERSTATE POWER AND LIGHT COMPANY
CONSOLIDATED BALANCE SHEETS

| December 31,
| 2020 |  | 2019
| (in millions, except per share and share amounts)
ASSETS |  |  |
Current assets: |  |  |
Cash and cash equivalents | $50 |  |  | $9 |
Accounts receivable, less allowance for expected credit losses | 210 |  |  | 203 |
Income tax refunds receivable | 26 |  |  | 11 |
Production fuel, at weighted average cost | 48 |  |  | 47 |
Gas stored underground, at weighted average cost | 20 |  |  | 22 |
Materials and supplies, at weighted average cost | 63 |  |  | 55 |
Regulatory assets | 52 |  |  | 44 |
Other | 27 |  |  | 18 |
Total current assets | 496 |  |  | 409 |
Property, plant and equipment, net | 7,889 |  |  | 7,481 |
Other assets: |  |  |
Regulatory assets | 1,431 |  |  | 1,356 |
Deferred charges and other | 33 |  |  | 31 |
Total other assets | 1,464 |  |  | 1,387 |
Total assets | $9,849 |  |  | $9,277 |

LIABILITIES AND EQUITY |  |  |
Current liabilities: |  |  |
Current maturities of long-term debt | $— |  |  | $200 |
Accounts payable | 162 |  |  | 207 |
Accounts payable to associated companies | 45 |  |  | 39 |
Regulatory liabilities | 103 |  |  | 116 |
Accrued taxes | 54 |  |  | 63 |
Accrued interest | 34 |  |  | 37 |
Other | 49 |  |  | 168 |
Total current liabilities | 447 |  |  | 830 |
Long-term debt, net (excluding current portion) | 3,345 |  |  | 2,947 |
Other liabilities: |  |  |
Deferred tax liabilities | 1,035 |  |  | 1,008 |
Regulatory liabilities | 573 |  |  | 599 |
Pension and other benefit obligations | 186 |  |  | 168 |
Other | 299 |  |  | 253 |
Total other liabilities | 2,093 |  |  | 2,028 |
Commitments and contingencies (Note 17) |  |  |
Equity: |  |  |
Interstate Power and Light Company common equity: |  |  |
Common stock - $2.50 par value - 24,000,000 shares authorized; 13,370,788 shares outstanding | 33 |  |  | 33 |
Additional paid-in capital | 2,752 |  |  | 2,348 |
Retained earnings | 979 |  |  | 891 |
Total Interstate Power and Light Company common equity | 3,764 |  |  | 3,272 |
Cumulative preferred stock | 200 |  |  | 200 |
Total equity | 3,964 |  |  | 3,472 |
Total liabilities and equity | $9,849 |  |  | $9,277 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY
CONSOLIDATED STATEMENTS OF CASH FLOWS

| Year Ended December 31,
| 2020 |  | 2019 |  | 2018
| (in millions)
Cash flows from (used for) operating activities: |  |  |  |  |
Net income | $334 |  |  | $294 |  |  | $274 |
Adjustments to reconcile net income to net cash flows from (used for) operating activities: |  |  |  |  |
Depreciation and amortization | 356 |  |  | 327 |  |  | 283 |
Deferred tax expense (benefit) and tax credits | (52) |  |  | 15 |  |  | 2 |
Equity component of allowance for funds used during construction | (17) |  |  | (35) |  |  | (29) |
Other | 12 |  |  | 1 |  |  | 4 |
Other changes in assets and liabilities: |  |  |  |  |
Accounts receivable | (466) |  |  | (467) |  |  | (494) |
Regulatory assets | (93) |  |  | (11) |  |  | (20) |
Accounts payable | 6 |  |  | (21) |  |  | (25) |
Regulatory liabilities | (20) |  |  | 2 |  |  | 1 |
Deferred income taxes | 79 |  |  | 35 |  |  | 44 |
DAEC PPA amendment buyout payment | (110) |  |  | — |  |  | — |
Other | (35) |  |  | 33 |  |  | (45) |
Net cash flows from (used for) operating activities | (6) |  |  | 173 |  |  | (5) |
Cash flows used for investing activities: |  |  |  |  |
Construction and acquisition expenditures | (687) |  |  | (1,020) |  |  | (991) |
Cash receipts on sold receivables | 458 |  |  | 413 |  |  | 605 |
Other | (72) |  |  | (60) |  |  | (44) |
Net cash flows used for investing activities | (301) |  |  | (667) |  |  | (430) |
Cash flows from financing activities: |  |  |  |  |
Common stock dividends | (236) |  |  | (168) |  |  | (168) |
Capital contributions from parent | 404 |  |  | 125 |  |  | 425 |
Proceeds from issuance of long-term debt | 400 |  |  | 600 |  |  | 500 |
Payments to retire long-term debt | (200) |  |  | — |  |  | (350) |
Net change in commercial paper | — |  |  | (50) |  |  | 50 |
Other | (20) |  |  | (16) |  |  | (17) |
Net cash flows from financing activities | 348 |  |  | 491 |  |  | 440 |
Net increase (decrease) in cash, cash equivalents and restricted cash | 41 |  |  | (3) |  |  | 5 |
Cash, cash equivalents and restricted cash at beginning of period | 9 |  |  | 12 |  |  | 7 |
Cash, cash equivalents and restricted cash at end of period | $50 |  |  | $9 |  |  | $12 |
Supplemental cash flows information: |  |  |  |  |
Cash (paid) refunded during the period for: |  |  |  |  |
Interest | ($141) |  |  | ($122) |  |  | ($120) |
Income taxes, net | ($18) |  |  | $7 |  |  | ($24) |
Significant non-cash investing and financing activities: |  |  |  |  |
Accrued capital expenditures | $73 |  |  | $112 |  |  | $187 |
Beneficial interest obtained in exchange for securitized accounts receivable | $188 |  |  | $188 |  |  | $119 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY
CONSOLIDATED STATEMENTS OF EQUITY

| Total IPL Common Equity |  |  |  |
|  |  | Additional |  |  |  | Cumulative |  |
| Common |  | Paid-In |  | Retained |  | Preferred |  | Total
| Stock |  | Capital |  | Earnings |  | Stock |  | Equity
| (in millions)
2018: |  |  |  |  |  |  |  |  |
Beginning balance | $33 |  | $1,798 |  |  | $679 |  | $200 |  | $2,710 |
Net income available for common stock |  |  |  |  | 264 |  |  |  | 264 |
Common stock dividends |  |  |  |  | (168) |  |  |  | (168) |
Capital contributions from parent |  |  | 425 |  |  |  |  |  |  | 425 |
Ending balance | 33 |  | 2,223 |  |  | 775 |  | 200 |  | 3,231 |
2019: |  |  |  |  |  |  |  |  |
Net income available for common stock |  |  |  |  | 284 |  |  |  | 284 |
Common stock dividends |  |  |  |  | (168) |  |  |  | (168) |
Capital contributions from parent |  |  | 125 |  |  |  |  |  |  | 125 |
Ending balance | 33 |  | 2,348 |  |  | 891 |  | 200 |  | 3,472 |
2020: |  |  |  |  |  |  |  |  |
Net income available for common stock |  |  |  |  | 324 |  |  |  | 324 |
Common stock dividends |  |  |  |  | (236) |  |  |  | (236) |
Capital contributions from parent |  |  | 404 |  |  |  |  |  |  | 404 |
Ending balance | $33 |  | $2,752 |  |  | $979 |  | $200 |  | $3,964 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
To the Shareowner and the Board of Directors of Wisconsin Power and Light Company:
Opinion on the Financial Statements
We have audited the accompanying consolidated balance sheets of Wisconsin Power and Light Company and subsidiary (the “Company”) as of December 31, 2020 and 2019, the related consolidated statements of income, equity, and cash flows, for each of the three years in the period ended December 31, 2020, and the related notes and the schedule listed in the Index at Item 15 (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2020 and 2019, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2020, in conformity with accounting principles generally accepted in the United States of America.
Basis for Opinion
These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.
Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.
Critical Audit Matter
The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.
Regulatory Assets and Regulatory Liabilities - Impact of rate regulation on the financial statements - Refer to Notes 1 and 2 to the financial statements
Critical Audit Matter Description
Wisconsin Power and Light Company is subject to rate regulation by the Federal Energy Regulatory Commission and state commission in Wisconsin (collectively, the “regulatory agencies”). Management has determined it meets the requirements under accounting principles generally accepted in the United States of America to prepare its financial statements applying the Regulated Operations Topic 980 of the Financial Accounting Standards Board’s Accounting Standards Codification. As of December 31, 2020, the Company had a recorded consolidated regulatory assets balance of $527 million and regulatory liabilities balance of $630 million.
The Company’s rates are subject to regulatory rate-setting processes and annual earnings oversight. The regulation of rates is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital. Regulatory assets represent incurred costs that have been deferred and are probable of recovery in future customer rates. Regulatory liabilities represent obligations to make refunds to customers or amounts collected in rates for which the costs have not yet been incurred. The Company’s regulatory assets and regulatory liabilities are recognized in accordance with the rulings of the regulatory agencies. A change in these rulings may result in a material impact on results of operations and the amount of assets and liabilities in the financial statements. Future regulatory rulings may impact the carrying value and accounting treatment of the regulatory assets and regulatory liabilities.

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We identified the impact of rate regulation as a critical audit matter due to the significant judgments made by management to support its assertions about impacted account balances and disclosures and the high degree of subjectivity involved in assessing the impact of future regulatory orders on the financial statements. Management judgments include assessing the likelihood of the recovery of incurred costs and refund of obligations to customers in future rates. Given that management’s accounting judgments are based on assumptions about the outcome of future decisions by the regulatory agencies, auditing these judgments required specialized knowledge of accounting for rate regulation and the rate-setting process due to its inherent complexities.
How the Critical Audit Matter Was Addressed in the Audit
Our audit procedures related to the regulatory filings by management and the uncertainty of future decisions by the regulatory agencies included the following, among others:
•We tested the design and operating effectiveness of management’s controls over the evaluation of regulatory assets and liabilities, including the monitoring and evaluation of regulatory developments that may affect the likelihood of recovering costs in future rates or of a future reduction in rates.
•We inspected the Company’s analysis supporting the probability of recovery for regulatory assets or refund or future reduction in rates for regulatory liabilities not yet addressed in a regulatory order to assess the reasonability of management’s assertions.
•We inquired of management regarding current events impacting the Company and inspected minutes of the board of directors and other committees of the Company and evaluated whether matters were identified that may have an impact on recorded regulatory asset and liability balances.
•We read relevant regulatory orders, regulatory statutes, interpretations, procedural memorandums, filings made by interveners, and other publicly available information issued by the regulatory agencies that pertain to the Company as well as to other relevant public utilities. We evaluated the external information and assessed whether there were matters in such information that would be contradictory to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.
•We obtained representation letters from management and evaluated such letters to assess whether information was present that would be relevant to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.
•We evaluated the Company’s disclosures related to the impacts of rate regulation and regulatory developments, including disclosures related to the regulatory balances recorded.
/s/ DELOITTE & TOUCHE LLP
Milwaukee, Wisconsin
February 19, 2021
We have served as the Company’s auditor since 2002.

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WISCONSIN POWER AND LIGHT COMPANY
CONSOLIDATED STATEMENTS OF INCOME

| Year Ended December 31,
| 2020 |  | 2019 |  | 2018
| (in millions)
Revenues: |  |  |  |  |
Electric utility | $1,225 |  |  | $1,283 |  |  | $1,269 |
Gas utility | 165 |  |  | 191 |  |  | 181 |
Other | 5 |  |  | 2 |  |  | 3 |
Total revenues | 1,395 |  |  | 1,476 |  |  | 1,453 |
Operating expenses: |  |  |  |  |
Electric production fuel and purchased power | 300 |  |  | 342 |  |  | 386 |
Electric transmission service | 151 |  |  | 141 |  |  | 143 |
Cost of gas sold | 83 |  |  | 102 |  |  | 103 |
Other operation and maintenance | 254 |  |  | 261 |  |  | 242 |
Depreciation and amortization | 254 |  |  | 236 |  |  | 219 |
Taxes other than income taxes | 47 |  |  | 47 |  |  | 47 |
Total operating expenses | 1,089 |  |  | 1,129 |  |  | 1,140 |
Operating income | 306 |  |  | 347 |  |  | 313 |
Other (income) and deductions: |  |  |  |  |
Interest expense | 104 |  |  | 102 |  |  | 98 |
Allowance for funds used during construction | (31) |  |  | (43) |  |  | (34) |
Other | 3 |  |  | 6 |  |  | 5 |
Total other (income) and deductions | 76 |  |  | 65 |  |  | 69 |
Income before income taxes | 230 |  |  | 282 |  |  | 244 |
Income tax expense (benefit) | (19) |  |  | 49 |  |  | 36 |
Net income | $249 |  |  | $233 |  |  | $208 |

Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of WPL’s common stock outstanding during the periods presented.
Refer to accompanying Combined Notes to Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY
CONSOLIDATED BALANCE SHEETS

| December 31,
| 2020 |  | 2019
| (in millions, except per share and share amounts)
ASSETS |  |  |
Current assets: |  |  |
Cash and cash equivalents | $3 |  |  | $4 |
Accounts receivable, less allowance for expected credit losses | 192 |  |  | 191 |
Production fuel, at weighted average cost | 18 |  |  | 31 |
Gas stored underground, at weighted average cost | 26 |  |  | 27 |
Materials and supplies, at weighted average cost | 40 |  |  | 43 |
Regulatory assets | 29 |  |  | 43 |
Prepaid gross receipts tax | 42 |  |  | 42 |
Other | 12 |  |  | 62 |
Total current assets | 362 |  |  | 443 |
Property, plant and equipment, net | 6,022 |  |  | 5,638 |
Other assets: |  |  |
Regulatory assets | 498 |  |  | 402 |
Deferred charges and other | 30 |  |  | 24 |
Total other assets | 528 |  |  | 426 |
Total assets | $6,912 |  |  | $6,507 |

LIABILITIES AND EQUITY |  |  |
Current liabilities: |  |  |
Current maturities of long-term debt | $— |  |  | $150 |
Commercial paper | 257 |  |  | 168 |
Accounts payable | 154 |  |  | 160 |
Accounts payable to associated companies | 35 |  |  | 42 |
Regulatory liabilities | 146 |  |  | 96 |
Other | 82 |  |  | 74 |
Total current liabilities | 674 |  |  | 690 |
Long-term debt, net (excluding current portion) | 2,130 |  |  | 1,783 |
Other liabilities: |  |  |
Deferred tax liabilities | 702 |  |  | 626 |
Regulatory liabilities | 484 |  |  | 613 |
Finance lease obligations - Sheboygan Falls Energy Facility | 42 |  |  | 51 |
Pension and other benefit obligations | 222 |  |  | 211 |
Other | 180 |  |  | 169 |
Total other liabilities | 1,630 |  |  | 1,670 |
Commitments and contingencies (Note 17) |  |  |
Equity: |  |  |
Wisconsin Power and Light Company common equity: |  |  |
Common stock - $5 par value - 18,000,000 shares authorized; 13,236,601 shares outstanding | 66 |  |  | 66 |
Additional paid-in capital | 1,459 |  |  | 1,434 |
Retained earnings | 953 |  |  | 864 |
Total Wisconsin Power and Light Company common equity | 2,478 |  |  | 2,364 |
Total liabilities and equity | $6,912 |  |  | $6,507 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY
CONSOLIDATED STATEMENTS OF CASH FLOWS

| Year Ended December 31,
| 2020 |  | 2019 |  | 2018
| (in millions)
Cash flows from operating activities: |  |  |  |  |
Net income | $249 |  |  | $233 |  |  | $208 |
Adjustments to reconcile net income to net cash flows from operating activities: |  |  |  |  |
Depreciation and amortization | 254 |  |  | 236 |  |  | 219 |
Deferred tax expense (benefit) and tax credits | (15) |  |  | 24 |  |  | 50 |
Other | 2 |  |  | (12) |  |  | (17) |
Other changes in assets and liabilities: |  |  |  |  |
Regulatory liabilities | (93) |  |  | (42) |  |  | 1 |
Deferred income taxes | 90 |  |  | 20 |  |  | 9 |
Other | (21) |  |  | (36) |  |  | (13) |
Net cash flows from operating activities | 466 |  |  | 423 |  |  | 457 |
Cash flows used for investing activities: |  |  |  |  |
Construction and acquisition expenditures | (606) |  |  | (519) |  |  | (578) |
Other | (7) |  |  | (38) |  |  | (30) |
Net cash flows used for investing activities | (613) |  |  | (557) |  |  | (608) |
Cash flows from financing activities: |  |  |  |  |
Common stock dividends | (160) |  |  | (144) |  |  | (140) |
Capital contribution from parent | 25 |  |  | 125 |  |  | 200 |
Proceeds from issuance of long-term debt | 350 |  |  | 350 |  |  | — |
Payments to retire long-term debt | (150) |  |  | (250) |  |  | — |
Net change in commercial paper | 89 |  |  | 63 |  |  | 81 |
Other | (8) |  |  | (15) |  |  | (5) |
Net cash flows from financing activities | 146 |  |  | 129 |  |  | 136 |
Net decrease in cash, cash equivalents and restricted cash | (1) |  |  | (5) |  |  | (15) |
Cash, cash equivalents and restricted cash at beginning of period | 4 |  |  | 9 |  |  | 24 |
Cash, cash equivalents and restricted cash at end of period | $3 |  |  | $4 |  |  | $9 |
Supplemental cash flows information: |  |  |  |  |
Cash (paid) refunded during the period for: |  |  |  |  |
Interest | ($102) |  |  | ($103) |  |  | ($98) |
Income taxes, net | $13 |  |  | ($29) |  |  | $14 |
Significant non-cash investing and financing activities: |  |  |  |  |
Accrued capital expenditures | $55 |  |  | $82 |  |  | $102 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY
CONSOLIDATED STATEMENTS OF EQUITY

|  |  | Additional |  |  |  |  |  | Total
| Common |  | Paid-In |  | Retained |  |  |  | Common
| Stock |  | Capital |  | Earnings |  |  |  | Equity
| (in millions)
2018: |  |  |  |  |  |  |  |  |
Beginning balance | $66 |  | $1,109 |  | $707 |  |  |  | $1,882 |
Net income |  |  |  |  | 208 |  |  |  | 208 |
Common stock dividends |  |  |  |  | (140) |  |  |  | (140) |
Capital contributions from parent |  |  | 200 |  |  |  |  |  | 200 |
Ending balance | 66 |  | 1,309 |  | 775 |  |  |  | 2,150 |
2019: |  |  |  |  |  |  |  |  |
Net income |  |  |  |  | 233 |  |  |  | 233 |
Common stock dividends |  |  |  |  | (144) |  |  |  | (144) |
Capital contributions from parent |  |  | 125 |  |  |  |  |  | 125 |
Ending balance | 66 |  | 1,434 |  | 864 |  |  |  | 2,364 |
2020: |  |  |  |  |  |  |  |  |
Net income |  |  |  |  | 249 |  |  |  | 249 |
Common stock dividends |  |  |  |  | (160) |  |  |  | (160) |
Capital contributions from parent |  |  | 25 |  |  |  |  |  | 25 |
Ending balance | $66 |  | $1,459 |  | $953 |  |  |  | $2,478 |

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION
INTERSTATE POWER AND LIGHT COMPANY
WISCONSIN POWER AND LIGHT COMPANY
COMBINED NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
NOTE 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
NOTE 1(a) General -
Description of Business - Alliant Energy’s financial statements include the accounts of Alliant Energy and its consolidated subsidiaries. Alliant Energy is a Midwest U.S. energy holding company, whose primary wholly-owned subsidiaries are IPL, WPL, AEF and Corporate Services.
IPL’s financial statements include the accounts of IPL and its consolidated subsidiary, IPL SPE LLC, which is used for IPL’s sales of accounts receivable program. IPL is a direct subsidiary of Alliant Energy and is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa. IPL also sells electricity to wholesale customers in Minnesota, Illinois and Iowa, and is engaged in the generation and distribution of steam for two customers in Cedar Rapids, Iowa.
WPL’s financial statements include the accounts of WPL and its consolidated subsidiary. WPL is a direct subsidiary of Alliant Energy and is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Wisconsin. WPL also sells electricity to wholesale customers in Wisconsin.
AEF is comprised of Travero (formerly known as Transportation), ATI, a non-utility wind farm, the Sheboygan Falls Energy Facility and other non-utility holdings. Travero includes a short-line rail freight service in Iowa; a barge, rail and truck freight terminal on the Mississippi River; and freight brokerage and logistics management services. ATI, a wholly-owned subsidiary of AEF, holds all of Alliant Energy’s interest in ATC Holdings. The non-utility wind farm includes a 50% cash equity ownership interest in a 225 MW wind farm located in Oklahoma. The Sheboygan Falls Energy Facility is a 347 MW, simple-cycle, natural gas-fired EGU near Sheboygan Falls, Wisconsin, which is leased to WPL for an initial period of 20 years ending in 2025.
Corporate Services is the subsidiary formed to provide administrative services to Alliant Energy and its subsidiaries.
In March 2020, COVID-19 was declared a global pandemic, which has resulted in widespread travel restrictions, closures of commercial spaces and industrial facilities, and more people working from home in Alliant Energy’s service territories. For 2020, Alliant Energy, IPL and WPL considered the impact of COVID-19 on their overall business operations, financial condition, results of operations and cash flows, along with assumptions and estimates used. While the total expected impact of COVID-19 on future sales is currently unknown, Alliant Energy, IPL and WPL have experienced higher electric residential sales and lower electric commercial and industrial sales since the outset of the pandemic. The degree to which the COVID-19 pandemic may impact Alliant Energy, IPL and WPL in the future is currently unknown and will depend on future developments of the pandemic as well as possible additional actions by government and regulatory authorities.
Basis of Presentation - The financial statements reflect investments in controlled subsidiaries on a consolidated basis and Alliant Energy’s, IPL’s and WPL’s proportionate shares of jointly-owned utility EGUs. Unconsolidated investments that Alliant Energy and WPL do not control are accounted for under the equity method of accounting. Under the equity method of accounting, Alliant Energy and WPL initially record the investment at cost, and adjust the carrying amount of the investment to recognize their respective share of the earnings or losses of the investee. Dividends received from an investee reduce the carrying amount of the equity investment. Investments that do not meet the criteria for consolidation or the equity method of accounting are accounted for under the cost method.
All intercompany balances and transactions, other than certain transactions affecting the rate-making process at IPL and WPL, have been eliminated from the financial statements. Such transactions not eliminated include costs that are recoverable from customers through rate-making processes. The financial statements are prepared in conformity with GAAP, which give recognition to the rate-making practices of FERC and state commissions having regulatory jurisdiction.
Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Use of Estimates - The preparation of the financial statements requires management to make estimates and assumptions that affect: (a) the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements; and (b) the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
NOTE 1(b) Regulatory Assets and Regulatory Liabilities - Alliant Energy, IPL and WPL are subject to regulation by FERC and various state regulatory commissions. As a result, Alliant Energy, IPL and WPL are subject to GAAP provisions for regulated operations, which provide that rate-regulated public utilities record certain costs and credits allowed in the rate-

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making process in different periods than for non-utility entities. Regulatory assets generally represent incurred costs that have been deferred as such costs are probable of recovery in future customer rates. Regulatory liabilities generally represent obligations to make refunds to customers or amounts collected in rates for which the related costs have not yet been incurred. Amounts recorded as regulatory assets or regulatory liabilities are generally recognized in the income statements at the time they are reflected in rates.
NOTE 1(c) Income Taxes - The liability method of accounting is followed for deferred taxes, which requires the establishment of deferred tax assets and liabilities, as appropriate, for temporary differences between the tax basis of assets and liabilities and the amounts reported in the financial statements. Deferred taxes are recorded using currently enacted tax rates and estimates of state apportionment. Changes in deferred tax assets and liabilities associated with certain property-related differences at IPL are accounted for differently than other subsidiaries of Alliant Energy due to rate-making practices in Iowa. Rate-making practices in Iowa do not include the impact of certain deferred tax expenses (benefits) in the determination of retail rates. Based on these rate-making practices, deferred tax expense (benefit) related to these property-related differences at IPL is not recorded in the income statement but instead recorded to regulatory assets or regulatory liabilities until these temporary differences reverse. In Wisconsin, the PSCW allows rate recovery of deferred tax expense on all temporary differences.
Investment tax credits are deferred and amortized to income over the average lives of the related property. Federal Tax Reform repealed corporate federal alternative minimum tax and allowed unutilized alternative minimum tax credits to be refunded over four tax years beginning with the U.S. federal tax return for calendar year 2018. Pursuant to the Coronavirus Aid, Relief, and Economic Security Act, Alliant Energy received the remaining alternative minimum tax credits refunds in 2020. Other tax credits reduce income tax expense in the year claimed.
Alliant Energy files a consolidated federal income tax return and a combined return in Wisconsin, which include Alliant Energy and its subsidiaries. Alliant Energy subsidiaries with a presence in Iowa file as part of a consolidated return in Iowa.
Alliant Energy allocates consolidated income tax expense to its subsidiaries that are members of the group that file a consolidated or combined income tax return. IPL and WPL use the modified separate return approach for calculating their income tax provisions and related deferred tax assets and liabilities. IPL and WPL are assumed to file separate tax returns with the federal and state taxing authorities, except that net operating losses (and other current or deferred tax attributes) are characterized as realized (or realizable) by IPL and WPL when those tax attributes are realized (or realizable) by the consolidated tax return group of Alliant Energy (even if IPL and WPL would not otherwise have realized the attributes on a stand-alone basis). The difference in the income taxes recorded for IPL and WPL under the modified separate return method compared to the income taxes recorded on a separate return basis was not material in 2020, 2019 and 2018.
NOTE 1(d) Cash, Cash Equivalents and Restricted Cash - Cash and cash equivalents include short-term liquid investments that have original maturities of less than 90 days. At December 31, 2020, Alliant Energy’s and IPL’s cash and cash equivalents included $44 million and $44 million of money market fund investments, with interest rates of 0.04% and 0.04%, respectively. At December 31, 2020 and 2019, restricted cash primarily related to requirements in Sheboygan Power, LLC’s debt agreement.
NOTE 1(e) Property, Plant and Equipment -
Utility Plant -
General - Utility plant is recorded at the original cost of acquisition or construction, which includes material, labor, contractor services, AFUDC and allocable overheads, such as supervision, engineering, benefits, certain taxes and transportation. Repairs, replacements and renewals of items of property determined to be less than a unit of property or that do not increase the property’s life or functionality are charged to maintenance expense. Property, plant and equipment that is probable of being retired early is classified as plant anticipated to be retired early. Generally, ordinary retirements of utility plant and salvage value are netted and charged to accumulated depreciation upon removal from utility plant accounts and no gain or loss is recognized consistent with rate-making principles. However, if regulators have approved recovery of the remaining net book value of property, plant and equipment that is retired early, or such approval by regulators is probable, the remaining net book value is reclassified from property, plant and equipment to regulatory assets upon retirement.
Depreciation - IPL and WPL use a combination of remaining life and straight-line depreciation methods as approved by their respective regulatory commissions. The composite or group method of depreciation is used, in which a single depreciation rate is applied to the gross investment in a particular class of property. This method pools similar assets and then depreciates each group as a whole. Periodic depreciation studies are performed to determine the appropriate group lives, net salvage, estimated cost of removal and group depreciation rates. These depreciation studies are subject to review and approval by IPL’s and WPL’s respective regulatory commissions. Depreciation expense is included within the recoverable cost of service component of rates collected from customers. The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows:

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| IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Electric - generation | 3.5% |  | 3.8% |  | 3.6% |  | 3.5% |  | 3.6% |  | 3.6%
Electric - distribution | 2.8% |  | 2.9% |  | 2.8% |  | 2.6% |  | 2.6% |  | 2.6%
Electric - other | 5.2% |  | 5.3% |  | 4.7% |  | 6.1% |  | 5.8% |  | 5.7%
Gas | 3.3% |  | 3.3% |  | 3.2% |  | 2.4% |  | 2.5% |  | 2.5%
Other | 6.3% |  | 5.9% |  | 5.2% |  | 5.9% |  | 5.6% |  | 5.8%

AFUDC - AFUDC represents costs to finance construction additions, including a return on equity component and cost of debt component as required by regulatory accounting. AFUDC for IPL’s construction projects is calculated in accordance with FERC guidelines. AFUDC for WPL’s retail and wholesale jurisdiction construction projects is calculated in accordance with PSCW and FERC guidelines, respectively. The AFUDC rates, computed in accordance with the prescribed regulatory formula, were as follows:

| 2020 |  | 2019 |  | 2018
IPL (Wind generation CWIP) | 7.1% |  | 7.4% |  | 7.5%
IPL (other CWIP) | 7.2% |  | 7.5% |  | 7.5%
WPL (retail jurisdiction) | 7.0% |  | 6.8% |  | 7.7%
WPL (wholesale jurisdiction) | 6.3% |  | 6.9% |  | 7.2%

In accordance with their respective regulatory commission decisions, IPL applies its AFUDC rates to 100% of applicable CWIP balances and WPL generally applies its AFUDC rates to 50% of applicable CWIP balances. WPL may apply its AFUDC rates to 100% of the retail portion of the CWIP balances for construction projects requiring a CA or CPCN that were approved by the PSCW after its then most recent rate order, including West Riverside.
Non-utility and Other Property -
General - Non-utility property is recorded at the original cost of acquisition or construction, which includes material, labor and contractor services. Repairs, replacements and renewals of items of property determined to be less than a unit of property or that do not increase the property’s life or functionality are charged to maintenance expense. Upon retirement or sale of non-utility property, the original cost and related accumulated depreciation are removed from the accounts and any gain or loss is included in the income statements.
Costs related to software developed or obtained for internal use are capitalized and amortized on a straight-line basis over the estimated useful life of the related software. If software is retired prior to being fully amortized, the remaining book value is recorded as a loss in the income statements.
NOTE 1(f) Revenue Recognition -
Utility - Revenues from Alliant Energy’s utility business are primarily from electric and gas sales to customers. Utility revenues are recognized over time as services are rendered or commodities are delivered to customers, and include billed and unbilled components. The billed component is based on the reading of customers’ meters, which occurs on a systematic basis throughout each reporting period and represents the fair value of the services provided or commodities delivered. The unbilled component is estimated and recorded at the end of each reporting period based on estimated amounts of energy delivered to customers since the end of each customer’s last billing period. The unbilled component is based on estimates of daily system demand volumes, customer usage by class, temperature impacts, line losses and the most recent customer rates.
IPL and WPL accrue revenues from their wholesale customers to the extent that the actual net revenue requirements calculated in accordance with FERC-approved formula rates for the reporting period are higher or lower than the amounts billed to wholesale customers during such period. Regulatory assets or regulatory liabilities are recorded as the offset for these accrued revenues under formulaic rate-making programs. As of December 31, 2020, the related amounts accrued for IPL and WPL were not material.
IPL and WPL participate in bid/offer-based wholesale energy and ancillary services markets operated by MISO. The MISO transactions are grouped together, resulting in a net supply to or net purchase from MISO for each hour of each day. The net supply to MISO is recorded as bulk power sales in “Electric utility revenues” and the net purchase from MISO is recorded in “Electric production fuel and purchased power” in the income statements.
Non-utility - Revenues from Alliant Energy’s non-utility businesses are primarily from its Travero business and are recognized over time as services are rendered to customers.
Taxes Collected from Customers - Sales or various other taxes collected by certain of Alliant Energy’s subsidiaries on behalf of other agencies are recorded on a net basis and are not included in revenues.

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Other - Alliant Energy, IPL and WPL do not disclose the value of unsatisfied performance obligations for: (i) contracts with an original expected length of one year or less; and (ii) contracts for which revenue is recognized at the amount to which they have the right to invoice for services performed.
NOTE 1(g) Utility Cost Recovery Mechanisms
Electric Production Fuel and Purchased Power (Fuel-related Costs) - Fuel-related costs are incurred to generate and purchase electricity to meet the demand of IPL’s and WPL’s electric customers. These fuel-related costs include the cost of fossil fuels (primarily natural gas and coal) used to produce electricity at their EGUs, and electricity purchased from MISO wholesale energy markets and under PPAs. These fuel-related costs are recorded in “Electric production fuel and purchased power” in the income statements.
IPL Retail - The cost recovery mechanisms for IPL’s retail electric customers provide for monthly adjustments to their electric rates for changes in fuel-related costs. Changes in the under-/over-collection of these costs are recognized in “Electric production fuel and purchased power” in Alliant Energy’s and IPL’s income statements. The cumulative effects of the under-/over-collection of these costs are recorded in regulatory assets or regulatory liabilities on Alliant Energy’s and IPL’s balance sheets until they are reflected in future billings to customers.
WPL Retail - The cost recovery mechanism for WPL’s retail electric customers is based on forecasts of certain fuel-related costs expected to be incurred during forward-looking test periods and fuel monitoring ranges determined by the PSCW during each retail electric rate proceeding or in a separate fuel cost plan approval proceeding. If WPL’s actual fuel-related costs fall outside these fuel monitoring ranges, WPL is authorized to defer the incremental under-/over-collection of fuel-related costs that are outside the approved ranges. Deferral of under-collections are reduced to the extent actual return on common equity earned by WPL during the fuel cost plan year exceeds the most recently authorized return on common equity. Deferred amounts for fuel-related costs outside the approved fuel monitoring ranges are recognized in “Electric production fuel and purchased power” in Alliant Energy’s and WPL’s income statements. The cumulative effects of these deferred amounts are recorded in regulatory assets or regulatory liabilities on Alliant Energy’s and WPL’s balance sheets until they are reflected in future billings to customers.
IPL and WPL Wholesale - The cost recovery mechanisms for IPL’s and WPL’s wholesale electric customers provide for subsequent adjustments to their electric rates for changes in fuel-related costs. Changes in the under-/over-collection of these costs are recognized in “Electric production fuel and purchased power” in the income statements. The cumulative effects of the under-/over-collection of these costs are recorded in regulatory assets or regulatory liabilities on the balance sheets until they are reflected in future billings to customers.
Purchased Electric Capacity - PPAs help meet the electricity demand of IPL’s and WPL’s customers. Certain PPAs include minimum payments for IPL’s and WPL’s rights to electric generating capacity, which are charged each period to “Electric production fuel and purchased power” in the income statements. Purchased electric capacity expenses are recovered from IPL’s and WPL’s retail electric customers through changes in base rates determined during periodic rate proceedings. Purchased electric capacity expenses are recovered from IPL’s and WPL’s wholesale electric customers through annual changes in base rates determined by a formula rate structure.
Electric Transmission Service - Costs incurred for the transmission of electricity to meet the demands of IPL’s and WPL’s customers are charged to “Electric transmission service” in the income statements.
IPL Retail - Electric transmission service expense is recovered from IPL’s retail electric customers through a transmission cost rider. This cost recovery mechanism provides for periodic adjustments to electric rates charged to retail electric customers for changes in electric transmission service expense. Changes in the under-/over-collection of these costs are recognized in “Electric transmission service” in Alliant Energy’s and IPL’s income statements. The cumulative effects of the under-/over-collection of these costs are recorded in regulatory assets or regulatory liabilities on Alliant Energy’s and IPL’s balance sheets until they are reflected in future billings to customers.
WPL Retail - Electric transmission service expense is recovered from WPL’s retail electric customers through changes in base rates determined during periodic rate proceedings. Pursuant to escrow accounting treatment approved by the PSCW, the difference between actual electric transmission service expense incurred and the amount of electric transmission service costs collected from customers as electric revenues is recognized in “Electric transmission service” in Alliant Energy’s and WPL’s income statements. An offsetting amount is recorded in regulatory assets or regulatory liabilities on Alliant Energy’s and WPL’s balance sheets until reflected in future billings to customers.
IPL and WPL Wholesale - IPL and WPL arrange transmission service for the majority of their respective wholesale electric customers. Electric transmission service expense is allocated to and recovered from these customers based on a load ratio share computation.
Cost of Gas Sold - Costs are incurred for the purchase, transportation and storage of natural gas to serve IPL’s and WPL’s gas customers and the costs associated with the natural gas delivered to customers are charged to “Cost of gas sold” in the income statements. The tariffs for IPL’s and WPL’s retail gas customers provide for subsequent adjustments to their rates

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each month for changes in the cost of gas sold. Changes in the under-/over-collection of these costs are also recognized in “Cost of gas sold” in the income statements. The cumulative effects of the under-/over-collection of these costs are recorded in regulatory assets or regulatory liabilities on the balance sheets until they are reflected in future billings to customers.
Energy Efficiency Costs - Costs incurred to fund energy efficiency programs and initiatives that help customers reduce their energy usage are charged to “Other operation and maintenance” in the income statements. Energy efficiency costs incurred by IPL are recovered from its retail electric and gas customers through energy efficiency and demand response cost recovery factor tariffs, which are revised annually and include a reconciliation to eliminate any under-/over-collection of energy efficiency costs from prior periods. Energy efficiency costs incurred by WPL are recovered from retail electric and gas customers through changes in base rates determined during periodic rate proceedings. Reconciliations of any under-/over-collection of energy efficiency costs from prior periods are also addressed in WPL’s periodic rate proceedings. Changes in the under-/over-collection of energy efficiency costs for IPL and WPL are recognized in “Other operation and maintenance” in the income statements. The cumulative effects of the under-/over-collection of these costs for IPL and WPL are recorded in regulatory assets or regulatory liabilities on the balance sheets until they are reflected in future billings to customers.
Renewable Energy Rider - Effective with the implementation of final rates covering the 2020 forward-looking Test Period, IPL recovers a return of, as well as earn a return on, its new wind generation placed in service in 2019 and 2020 from its retail electric customers through a renewable energy rider. Other applicable costs and tax benefits associated with the new wind generation, excluding operation and maintenance expenses, are also included in the rider. This cost recovery mechanism provides for annual adjustments to electric rates charged to IPL’s retail electric customers for actual renewable energy costs and tax benefits. Changes in the under-/over-collection of these costs are recognized in “Electric utility revenue” in Alliant Energy’s and IPL’s income statements. The cumulative effects of the under-/over-collection of these costs for IPL are recorded in regulatory assets or regulatory liabilities on Alliant Energy’s and IPL’s balance sheets until they are reflected in future billings to customers.
NOTE 1(h) Financial Instruments - Financial instruments are periodically used for risk management purposes to mitigate exposures to fluctuations in certain commodity prices and transmission congestion costs. The fair value of those financial instruments that are determined to be derivatives are recorded as assets or liabilities on the balance sheets. Certain commodity purchase and sales contracts qualified for and were designated under the normal purchase and sale exception, and were accounted for on the accrual basis of accounting. Alliant Energy, IPL and WPL have elected to not net the fair value amounts of derivatives subject to a master netting arrangement by counterparty. Alliant Energy, IPL and WPL do not offset fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) against fair value amounts recognized for derivative instruments that are executed with the same counterparty under the same master netting arrangement. Refer to Note 2 for discussion of the recognition of regulatory assets and regulatory liabilities related to the unrealized losses and gains on derivative instruments. Refer to Notes 15, 16 and 17(f) for further discussion of derivatives and related credit risk.
NOTE 1(i) Asset Impairments -
Property, Plant and Equipment of Regulated Operations - Property, plant and equipment of regulated operations are reviewed for possible impairment whenever events or changes in circumstances indicate all or a portion of the carrying value of the assets may be disallowed for rate-making purposes. If IPL or WPL are disallowed recovery of any portion of the carrying value of their regulated property, plant and equipment that is under construction, has been recently completed or is probable of abandonment, or conclude it is probable recovery will be disallowed, an impairment charge is recognized equal to the amount of the carrying value that was disallowed or is probable of being disallowed. If IPL or WPL are only allowed a partial return on the carrying value of their regulated property, plant and equipment that is under construction, has been recently completed or is probable of abandonment, or conclude it is probable a full return will not be allowed, an impairment charge is recognized equal to the difference between the carrying value and the present value of the future revenues expected from their regulated property, plant and equipment.
Property, Plant and Equipment of Non-utility Operations - Property, plant and equipment of non-utility operations are reviewed for possible impairment whenever events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Impairment is indicated if the carrying value of an asset exceeds its undiscounted future cash flows. If an impairment is indicated, a charge is recognized equal to the amount the carrying value exceeds the asset’s fair value.
Unconsolidated Equity Investments - If events or circumstances indicate the carrying value of investments accounted for under the equity method of accounting exceeds fair value and the decline in value is other than temporary, potential impairment is assessed. If an impairment is indicated, a charge is recognized equal to the amount the carrying value exceeds the investment’s fair value.
NOTE 1(j) Asset Retirement Obligations - The fair value of a legal obligation associated with the retirement of an asset is recorded as a liability when an asset is placed in service, when a legal obligation is subsequently identified or when sufficient information becomes available to determine a reasonable estimate of the fair value of future retirement costs. When an ARO is recorded as a liability, an equivalent amount is added to the asset cost. The fair value of AROs at inception is determined using discounted cash flows analyses. The liability is accreted to its present value and the capitalized cost is depreciated over the useful life of the related asset. Accretion and depreciation expenses related to AROs for IPL’s and WPL’s regulated

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operations are recorded to regulatory assets on the balance sheets. Upon regulatory approval to recover IPL’s AROs expenditures, its regulatory assets are amortized to depreciation and amortization expenses in Alliant Energy’s and IPL’s income statements over the same time period the ARO expenditures are recovered from IPL’s customers. WPL’s regulatory assets related to AROs are recovered as a component of depreciation rates pursuant to PSCW and FERC orders. Accretion and depreciation expenses related to AROs for Alliant Energy’s non-utility operations are recorded to depreciation and amortization expenses in Alliant Energy’s income statements. Upon settlement of the ARO liability, an entity settles the obligation for its recorded amount or incurs a gain or loss. Any gains or losses related to AROs for IPL’s and WPL’s regulated operations are recorded to regulatory liabilities or regulatory assets on the balance sheets.
NOTE 1(k) Debt Issuance and Retirement Costs - Debt issuance costs and debt premiums or discounts are presented on the balance sheets as a direct adjustment to the carrying amount of the related debt liability, and are deferred and amortized over the expected life of each debt issue, considering maturity dates and, if applicable, redemption rights held by others. Alliant Energy’s non-utility businesses and Corporate Services record to interest expense in the period of retirement any unamortized debt issuance costs and debt premiums or discounts on debt retired early.
NOTE 1(l) Current Expected Credit Losses Estimates - Current expected credit losses are estimated for trade and other receivables and credit exposures on guarantees of the performance by third parties. The current expected credit losses for short-term trade receivables are based on estimates of losses resulting from the inability of customers to make required payments. The methodology used to estimate losses is based on historical write-offs, regional economic conditions, significant events that could impact collectability, such as impacts related to COVID-19, the derecho windstorm and related regulatory actions, and forecasted changes to the accounts receivable aging portfolio and write-offs. The current expected credit losses related to guarantees of the performance by third parties are estimated using both quantitative and qualitative information, which utilizes potential outcomes in a range of possible estimated amounts.
NOTE 1(m) Variable Interest Entities - An entity is considered a VIE if its equity investors do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties, the entity is structured with disproportionate voting rights and substantially all of the entity’s activities are conducted on behalf of the investor with disproportionately fewer voting rights, or its equity investors lack any of the following characteristics: (1) power, through voting rights or similar rights, to direct the activities of the entity that most significantly impact the entity’s economic performance; (2) the obligation to absorb expected losses of the entity; or (3) the right to receive expected benefits of the entity. The primary beneficiary of a VIE is required to consolidate the VIE. The financial statements do not reflect any consolidation of VIEs.
NOTE 1(n) Leases - The determination of whether an arrangement qualifies as a lease occurs at the inception of the arrangement. Arrangements that qualify as leases are classified as either operating or finance. Operating and finance lease liabilities represent obligations to make payments arising from the lease. Operating and finance lease assets represent the right to use an underlying asset for the lease term and are recognized at the lease commencement date based on the present value of the lease payments over the lease term. Leases with initial terms less than 12 months are not recognized as leases. For operating leases, an incremental borrowing rate, as determined at the lease commencement date, is used to determine the present value of the lease payments. For finance leases, the rate implicit in the lease, if known, is used to determine the present value of the lease payments. Lease terms include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Operating lease expense is recognized on a straight-line basis over the expected lease term. Finance lease expense is comprised of depreciation and interest expenses. Finance lease assets are depreciated on a straight-line basis over the shorter of the useful life of the underlying asset or the lease term.
NOTE 1(o) New Accounting Standards -
Credit Losses - In 2016, the Financial Accounting Standards Board issued an accounting standard requiring use of a current expected credit loss model rather than an incurred loss method, which is intended to result in more timely recognition of credit losses on trade receivables, certain other assets and off-balance sheet credit exposures. Alliant Energy, IPL and WPL adopted this standard on January 1, 2020 using a modified retrospective method of adoption, which required cumulative effect adjustments to retained earnings on January 1, 2020. IPL and WPL did not record a cumulative effect adjustment to retained earnings and Alliant Energy recorded a pre-tax $12 million (after-tax $9 million) cumulative effect adjustment to decrease retained earnings related to Alliant Energy’s guarantees in the partnership obligations of an affiliate of Whiting Petroleum (refer to Note 17(d) for further discussion). This adjustment is included in “Adoption of new accounting standard” in Alliant Energy’s equity statement for 2020.
NOTE 2. REGULATORY MATTERS
Regulatory Assets - Alliant Energy, IPL and WPL assess whether IPL’s and WPL’s regulatory assets are probable of future recovery by considering factors such as applicable regulations, recent orders by the applicable regulatory agencies, historical treatment of similar costs by the applicable regulatory agencies and regulatory environment changes. Based on these assessments, Alliant Energy, IPL and WPL believe the regulatory assets recognized as of December 31, 2020 are probable of future recovery. However, no assurance can be made that IPL and WPL will recover all of these regulatory assets in future rates. If future recovery of a regulatory asset ceases to be probable, the regulatory asset will be charged to expense. At December 31, regulatory assets were comprised of the following items (in millions):

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| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Tax-related | $890 |  |  | $818 |  |  | $843 |  |  | $777 |  |  | $47 |  |  | $41 |
Pension and OPEB costs | 580 |  |  | 524 |  |  | 291 |  |  | 263 |  |  | 289 |  |  | 261 |
AROs | 119 |  |  | 112 |  |  | 81 |  |  | 76 |  |  | 38 |  |  | 36 |
Assets retired early | 113 |  |  | 134 |  |  | 77 |  |  | 88 |  |  | 36 |  |  | 46 |
IPL’s DAEC PPA amendment | 110 |  |  | 108 |  |  | 110 |  |  | 108 |  |  | — |  |  | — |
WPL’s Western Wisconsin gas distribution expansion investments | 55 |  |  | — |  |  | — |  |  | — |  |  | 55 |  |  | — |
Derivatives | 26 |  |  | 39 |  |  | 13 |  |  | 18 |  |  | 13 |  |  | 21 |
Other | 117 |  |  | 110 |  |  | 68 |  |  | 70 |  |  | 49 |  |  | 40 |
| $2,010 |  |  | $1,845 |  |  | $1,483 |  |  | $1,400 |  |  | $527 |  |  | $445 |

At December 31, 2020, IPL and WPL had $81 million and $11 million, respectively, of regulatory assets that were not earning a return. IPL’s regulatory assets that were not earning a return consisted primarily of retired analog electric meters, emission allowances, clean air compliance projects and debt redemption costs. WPL’s regulatory assets that were not earning a return consisted primarily of costs for future expansion projects and environmental-related costs. The other regulatory assets reported in the above table either earn a return or the cash has not yet been expended, in which case the assets are offset by liabilities that also do not incur a carrying cost.
Tax-related - IPL and WPL record regulatory assets for certain temporary differences (primarily related to utility property, plant and equipment at IPL) that result in a decrease in current rates charged to customers and an increase in future rates charged to customers based on the timing of income tax expense that is used to determine such rates. These temporary differences for IPL include the impacts of qualifying deductions for repairs expenditures, allocation of mixed service costs, and Iowa accelerated tax depreciation, which all contribute to lower current income tax expense during the first part of an asset’s useful life and higher current income tax expense during the latter part of an asset’s useful life. These regulatory assets will be recovered from customers in the future when these temporary differences reverse resulting in additional current income tax expense used to determine customers’ rates.
Pension and other postretirement benefits costs - The IUB, PSCW and FERC have authorized IPL and WPL to record the previously unrecognized net actuarial gains and losses, and prior service costs and credits, as regulatory assets in lieu of accumulated other comprehensive loss on the balance sheets, as these amounts are expected to be recovered in future rates. These regulatory assets will be increased or decreased as the net actuarial gains or losses, and prior service costs or credits, are subsequently amortized and recognized as a component of net periodic benefit costs. Regulatory assets are also increased or decreased as a result of the annual defined benefit plan measurement process. Pension and OPEB costs are included within the recoverable cost of service component of rates charged to IPL’s and WPL’s retail and wholesale customers, which are based upon pension and OPEB costs determined in accordance with GAAP and are calculated in accordance with IPL’s and WPL’s respective regulatory jurisdictions.
AROs - Alliant Energy, IPL and WPL believe it is probable that certain differences between expenses accrued for legal AROs related to their utility operations and expenses recovered currently in rates will be recoverable in future rates, and are deferring the differences as regulatory assets.
Assets retired early - IPL and WPL have retired various natural gas- and coal-fired EGUs, and IPL has retired certain analog electric meters. As a result, the remaining net book value of these assets was reclassified from property, plant and equipment to a regulatory asset on their respective balance sheets. Details regarding the recovery of the remaining net book value of these assets from IPL’s and WPL’s customers are as follows (dollars in millions):

Entity |  | Asset |  | Retirement Date |  | Regulatory Asset Balance as of Dec. 31, 2020 |  | Recovery |  | Regulatory Approval
IPL |  | Sutherland Units 1 and 3 |  | 2017 |  | $23 |  | Return of and return on remaining net book value through 2027 |  | IUB and FERC
IPL |  | M.L. Kapp Unit 2 |  | 2018 |  | 21 |  | Return of and return on remaining net book value through 2029 |  | IUB and FERC
IPL |  | Analog electric meters |  | 2019 |  | 33 |  | Return of remaining net book value through 2028 |  | IUB and FERC
WPL |  | Nelson Dewey Units 1 and 2 and Edgewater Unit 3 |  | 2015 |  | 13 |  | Return of and return on remaining net book value through 2022 |  | PSCW and FERC
WPL |  | Edgewater Unit 4 |  | 2018 |  | 23 |  | Return of and return on remaining net book value through 2028 |  | PSCW and FERC

IPL’s DAEC PPA Amendment - In September 2020, IPL made a buyout payment of $110 million in exchange for shortening the term of its DAEC PPA by 5 years. The payment was recorded as a reduction to “Other current liabilities” on Alliant Energy’s and IPL’s balance sheets and was included in “DAEC PPA amendment buyout payment” in Alliant Energy’s and IPL’s

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cash flows used for operating activities in 2020. The buyout payment, including a return on, will be recovered from IPL’s retail and wholesale customers from 2021 through the end of 2025.
WPL’s Western Wisconsin gas distribution expansion investments - WPL made contributions in aid of construction to a third party for investments as part of its Western Wisconsin gas distribution expansion project. Pursuant to authorization by the PSCW, Alliant Energy and WPL have recorded a regulatory asset for these costs, and are authorized by the PSCW to recover these amounts from WPL’s retail gas customers in base rates beginning in 2021.
Derivatives - In accordance with IPL’s and WPL’s fuel and natural gas recovery mechanisms, prudently incurred costs from derivative instruments are recoverable from customers in the future after any losses are realized, and gains from derivative instruments are refundable to customers in the future after any gains are realized. Based on these recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets.
Regulatory Liabilities - At December 31, regulatory liabilities were comprised of the following items (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Tax-related | $732 |  | $836 |  | $331 |  | $351 |  | $401 |  | $485
Cost of removal obligations | 367 |  | 388 |  | 238 |  | 257 |  | 129 |  | 131
Electric transmission cost recovery | 68 |  | 88 |  | 39 |  | 51 |  | 29 |  | 37
WPL’s West Riverside liquidated damages | 38 |  | — |  | — |  | — |  | 38 |  | —
Derivatives | 28 |  | 20 |  | 25 |  | 17 |  | 3 |  | 3
Other | 73 |  | 92 |  | 43 |  | 39 |  | 30 |  | 53
| $1,306 |  | $1,424 |  | $676 |  | $715 |  | $630 |  | $709

Tax-related regulatory liabilities reduce revenue requirement calculations utilized in IPL’s and WPL’s respective rate proceedings. Cost of removal obligations, to the extent expensed through depreciation rates, reduce rate base. A significant portion of the remaining regulatory liabilities is not used to adjust revenue requirement calculations.
Tax-related - Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities are primarily related to excess deferred tax benefits resulting from the remeasurement of accumulated deferred income taxes caused by Federal Tax Reform. The majority of these benefits related to accelerated depreciation are subject to tax normalization rules. These rules limit the rate at which these tax benefits are allowed to be passed on to customers.
Cost of removal obligations - Alliant Energy, IPL and WPL collect in rates future removal costs for many assets that do not have associated legal AROs. Alliant Energy, IPL and WPL record a regulatory liability for the amounts collected in rates for these future removal costs and reduce the regulatory liability for amounts spent on removal activities. Cash payments related to cost of removal obligations are included in “Other” in cash flows used for investing activities.
Electric transmission cost recovery - Refer to Note 1(g) for details of IPL’s and WPL’s electric transmission cost recovery mechanisms. In 2020, pursuant to a June 2020 IUB order, IPL issued $42 million of credits to its retail electric customers through its transmission cost rider for amounts previously collected in rates, which resulted in a reduction in regulatory liabilities and a corresponding reduction to “Electric transmission service” expense in Alliant Energy’s and IPL’s income statements during 2020.
Refer to Note 17(g) for discussion of refunds received by IPL and WPL in 2020 related to MISO transmission owner return on equity complaints, which were recorded to regulatory liabilities in 2020.
WPL’s West Riverside liquidated damages - Pursuant to terms included in the related West Riverside construction procurement contracts, WPL reached agreement with the contractor on liquidated damages in 2020. A significant portion of the liquidated damages was settled by WPL offsetting amounts owed to the contractor that were previously withheld for payment, which were non-cash investing activities. In December 2020, the PSCW authorized WPL to record the liquidated damages as a regulatory liability, which is expected to be returned to WPL’s customers as determined in future regulatory proceedings.
Derecho Windstorm - In August 2020, a derecho windstorm caused considerable damage to IPL’s electric distribution system in its service territory, and over 250,000 of its customers lost power. IPL completed its initial restoration and rebuilding efforts in August 2020 and permanent repairs to the system will continue into 2021. IPL’s current estimate of the total cost of the windstorm is approximately $140 million, and as of December 31, 2020, approximately $135 million was recorded substantially to “Property, plant and equipment, net” on Alliant Energy’s and IPL’s balance sheets. In December 2020, IPL received approval from the IUB for utilization of a regulatory account to track certain incremental costs and benefits incurred resulting from the windstorm until IPL’s next rate proceeding. Tax benefits and the incremental operation and maintenance expenses

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resulting from the windstorm were deferred and recorded as a net regulatory liability of $7 million as of December 31, 2020, which is included in “Other” regulatory liabilities in the above table.
Rate Reviews -
IPL’s Retail Electric Rate Review (2020 Forward-looking Test Period) - In March 2019, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers based on a 2020 forward-looking Test Period. The key drivers for IPL’s request included recovery of capital projects, including new wind generation. IPL concurrently filed for interim retail electric rates based on 2018 historical data as adjusted for certain known and measurable changes occurring in the first quarter of 2019. An interim retail electric base rate increase of $90 million, on an annual basis, was implemented effective April 1, 2019. In October 2019, IPL reached a settlement agreement with certain intervenor groups for an annual retail electric base rate increase of $127 million. In January 2020, the IUB issued an order approving the settlement with final rates, which were effective February 26, 2020. The agreement includes both the recovery of and a return on IPL’s early retired EGUs, and the recovery of IPL’s retired analog electric meters. In addition, as discussed in Note 1(g), the net impact of certain costs and benefits resulting from IPL’s 1,000 MW expansion of wind generation in 2019 and 2020 is being recovered from its retail electric customers through the renewable energy rider. The agreement also includes IPL providing retail electric billing credits, which began in the third quarter of 2020 and will continue through June 2021, and in aggregate include $27 million of excess deferred tax benefits and $8 million from a partial refund of interim rates implemented in 2019.
IPL’s Retail Gas Rate Review (2020 Forward-looking Test Period) - In March 2019, IPL filed a request with the IUB to increase annual gas base rates for its Iowa retail gas customers based on a 2020 forward-looking Test Period. In October 2019, IPL reached a settlement agreement with intervenor groups for an annual retail gas base rate increase of $12 million. In December 2019, the IUB issued an order approving the settlement with final rates, which were effective January 10, 2020.
IPL’s Retail Electric Rate Review (2016 Test Year) - In April 2017, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers based on a 2016 historical Test Year. An interim retail electric base rate increase of $102 million, on an annual basis, was implemented effective April 13, 2017. In September 2017, IPL reached a partial, non-unanimous settlement agreement with intervenor groups for an annual retail electric base rate increase of $130 million. In February 2018, the IUB issued an order approving the settlement with final rates effective May 1, 2018.
WPL’s Retail Electric and Gas Rate Review (2019/2020 Forward-looking Test Period) - In December 2018, the PSCW issued an order approving WPL’s proposed settlement for its retail electric and gas rate review covering the 2019/2020 Test Period, which was based on a stipulated agreement between WPL and intervenor groups. Under the settlement, WPL retail electric and gas base rates did not change from then current levels through the end of 2020. In September 2020, pursuant to an August 2020 PSCW order, WPL refunded $12 million of 2019 fuel-related cost over-collections to its retail electric customers. In addition, WPL’s amortization of excess deferred taxes resulting from the remeasurement of accumulated deferred income taxes caused by Federal Tax Reform was used to offset increases in WPL’s 2020 increased revenue requirements.
WPL’s Retail Fuel-related Rate Filing (2020 Forward-looking Test Period) - In December 2019, WPL received an order from the PSCW authorizing an annual retail electric rate decrease of $29 million, or approximately 2%, effective January 1, 2020. The decrease primarily reflected a change in expected fuel-related costs in 2020.

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NOTE 3. PROPERTY, PLANT AND EQUIPMENT
At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service | $8,222 |  |  | $7,625 |  |  | $4,884 |  |  | $4,432 |  |  | $3,338 |  |  | $3,193 |
Distribution in service | 6,216 |  |  | 5,783 |  |  | 3,470 |  |  | 3,190 |  |  | 2,746 |  |  | 2,593 |
Other in service | 536 |  |  | 457 |  |  | 358 |  |  | 299 |  |  | 178 |  |  | 158 |
Anticipated to be retired early (a) | 1,269 |  |  | — |  |  | 459 |  |  | — |  |  | 810 |  |  | — |
Total electric plant | 16,243 |  |  | 13,865 |  |  | 9,171 |  |  | 7,921 |  |  | 7,072 |  |  | 5,944 |
Gas plant in service | 1,563 |  |  | 1,463 |  |  | 844 |  |  | 802 |  |  | 719 |  |  | 661 |
Other plant in service | 534 |  |  | 520 |  |  | 354 |  |  | 345 |  |  | 180 |  |  | 175 |
Accumulated depreciation | (4,868) |  |  | (4,602) |  |  | (2,671) |  |  | (2,499) |  |  | (2,197) |  |  | (2,103) |
Net plant | 13,472 |  |  | 11,246 |  |  | 7,698 |  |  | 6,569 |  |  | 5,774 |  |  | 4,677 |
Leased Sheboygan Falls Energy Facility, net (b) | — |  |  | — |  |  | — |  |  | — |  |  | 27 |  |  | 32 |
Construction work in progress | 405 |  |  | 1,835 |  |  | 185 |  |  | 907 |  |  | 220 |  |  | 928 |
Other, net | 7 |  |  | 6 |  |  | 6 |  |  | 5 |  |  | 1 |  |  | 1 |
Total utility | 13,884 |  |  | 13,087 |  |  | 7,889 |  |  | 7,481 |  |  | 6,022 |  |  | 5,638 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (c) | 79 |  |  | 83 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (d) | 373 |  |  | 357 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 452 |  |  | 440 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment | $14,336 |  |  | $13,527 |  |  | $7,889 |  |  | $7,481 |  |  | $6,022 |  |  | $5,638 |

(a)In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring these EGUs by the end of 2022. Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5, met the criteria to be considered probable of abandonment as of December 31, 2020. IPL and WPL are currently allowed a full recovery of and a full return on its respective EGU from both its retail and wholesale customers.
(b)Less accumulated amortization of $95 million and $89 million for WPL as of December 31, 2020 and 2019, respectively. The leased Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.
(c)Less accumulated depreciation of $63 million and $59 million for Alliant Energy as of December 31, 2020 and 2019, respectively.
(d)Less accumulated depreciation of $210 million and $172 million for Alliant Energy as of December 31, 2020 and 2019, respectively.
AFUDC - AFUDC represents costs to finance construction additions, including a return on equity component and cost of debt component as required by regulatory accounting. The concurrent credit for the amount of AFUDC capitalized is recorded as “Allowance for funds used during construction” in the income statements. The amount of AFUDC generated by equity and debt components was as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Equity | $39 |  | $66 |  | $51 |  | $17 |  | $35 |  | $29 |  | $22 |  | $31 |  | $22
Debt | 16 |  | 27 |  | 25 |  | 7 |  | 15 |  | 13 |  | 9 |  | 12 |  | 12
| $55 |  | $93 |  | $76 |  | $24 |  | $50 |  | $42 |  | $31 |  | $43 |  | $34

Non-utility and Other - The non-utility and other property, plant and equipment recorded on Alliant Energy’s balance sheets include the following:
Non-utility Generation - The Sheboygan Falls Energy Facility was placed into service in 2005 and is depreciated using the straight-line method over a 35-year period.
Corporate Services and Other - Property, plant and equipment related to Corporate Services include a customer billing and information system for IPL and WPL and other computer software, and the corporate headquarters building located in Madison, Wisconsin. The customer billing and information system is amortized using the straight-line method over a 12-year period. The majority of the remaining software is amortized over a 5-year period. Other property, plant and equipment include Travero assets (a short-line railway in Iowa and a barge terminal on the Mississippi River). All Corporate Services and Other property, plant and equipment are depreciated using the straight-line method over periods ranging from 5 to 30 years.

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NOTE 4. JOINTLY-OWNED ELECTRIC UTILITY PLANT
Under joint ownership agreements with other utilities, IPL and WPL have undivided ownership interests in jointly-owned EGUs. Each of the respective owners is responsible for the financing of its portion of the construction costs. IPL’s and WPL’s shares of expenses from jointly-owned EGUs are included in the corresponding operating expenses (e.g., electric production fuel, other operation and maintenance, etc.) in the income statements. Information relative to IPL’s and WPL’s ownership interest in these jointly-owned EGUs at December 31, 2020 was as follows (dollars in millions):

| Ownership |  | Electric |  | Accumulated Provision |  | Construction
| Interest % |  | Plant |  | for Depreciation |  | Work in Progress
IPL |  |  |  |  |  |  |
Ottumwa Unit 1 | 48.0% |  | $580 |  | $195 |  | $22
George Neal Unit 4 | 25.7% |  | 192 |  | 96 |  | 2
George Neal Unit 3 | 28.0% |  | 171 |  | 67 |  | —
Louisa Unit 1 | 4.0% |  | 39 |  | 22 |  | —
|  |  | 982 |  | 380 |  | 24
WPL |  |  |  |  |  |  |
Columbia Units 1-2 | 53.5% |  | 786 |  | 289 |  | 4
West Riverside | 91.8% |  | 686 |  | 12 |  | 13
Forward Wind Energy Center | 42.6% |  | 120 |  | 46 |  | —
|  |  | 1,592 |  | 347 |  | 17
Alliant Energy |  |  | $2,574 |  | $727 |  | $41

NOTE 5. RECEIVABLES
NOTE 5(a) Accounts Receivable - Details for accounts receivable included on the balance sheets as of December 31 were as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Customer | $101 |  |  | $92 |  |  | $— |  |  | $— |  |  | $92 |  |  | $84 |
Unbilled utility revenues | 82 |  |  | 82 |  |  | — |  |  | — |  |  | 82 |  |  | 82 |
Deferred proceeds | 188 |  |  | 188 |  |  | 188 |  |  | 188 |  |  | — |  |  | — |
Other | 59 |  |  | 47 |  |  | 23 |  |  | 16 |  |  | 35 |  |  | 31 |
Allowance for expected credit losses | (18) |  |  | (7) |  |  | (1) |  |  | (1) |  |  | (17) |  |  | (6) |
| $412 |  |  | $402 |  |  | $210 |  |  | $203 |  |  | $192 |  |  | $191 |

NOTE 5(b) Sales of Accounts Receivable - IPL maintains a Receivables Agreement whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. The purchase commitment from the third party to which it sells its receivables expires in March 2021. IPL currently expects to amend and extend the purchase commitment. IPL pays a monthly fee to the third party that varies based on interest rates, limits on cash proceeds and cash amounts received from the third party. Deferred proceeds represent IPL’s interest in the receivables sold to the third party. At IPL’s request, deferred proceeds are paid to IPL from collections of receivables, after paying any required expenses incurred by the third party and the collection agent. Corporate Services acts as collection agent for the third party and receives a fee for collection services. The Receivables Agreement can be terminated by the third party if arrears or write-offs exceed certain levels. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. IPL believes that the allowance for expected credit losses related to its sales of receivables is a reasonable approximation of credit risk of the customers that generated the receivables. Refer to Note 16 for discussion of the fair value of deferred proceeds.
Under the Receivables Agreement, IPL has the right to receive cash proceeds, up to a certain limit, from the third party in exchange for the receivables sold. The limit on cash proceeds fluctuates between $90 million and $110 million. Cash proceeds are used by IPL to meet short-term financing needs, and cannot exceed the current limit or amount of receivables available for sale, whichever is less. As of December 31, 2020, IPL had $109 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program were as follows (in millions):

| Maximum |  | Average
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Outstanding aggregate cash proceeds | $96 |  | $108 |  | $116 |  | $9 |  | $36 |  | $53

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As of December 31, the attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

| 2020 |  | 2019
Customer accounts receivable | $114 |  | $125
Unbilled utility revenues | 92 |  | 95
Other receivables | — |  | 1
Receivables sold to third party | 206 |  | 221
Less: cash proceeds | 1 |  | 27
Deferred proceeds | 205 |  | 194
Less: allowance for expected credit losses | 17 |  | 6
Fair value of deferred proceeds | $188 |  | $188
Outstanding receivables past due | $27 |  | $26

Additional attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

| 2020 |  | 2019 |  | 2018
Collections | $2,025 |  | $2,193 |  | $2,077
Write-offs, net of recoveries | 7 |  | 19 |  | 21

NOTE 6. INVESTMENTS
Unconsolidated Equity Investments - Alliant Energy’s unconsolidated investments accounted for under the equity method of accounting are as follows (in millions):

| Ownership Interest at |  | Carrying Value at December 31, |  | Equity (Income) / Loss
| December 31, 2020 |  | 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2018
ATC Holdings | 16%, 20% |  | $331 |  | $320 |  | ($47) |  | ($45) |  | ($38)
Non-utility wind farm in Oklahoma | 50% |  | 103 |  | 105 |  | (8) |  | (5) |  | (16)
Other | Various |  | 42 |  | 33 |  | (6) |  | (3) |  | (1)
|  |  | $476 |  | $458 |  | ($61) |  | ($53) |  | ($55)

Summary aggregate financial information from the financial statements of these holdings is as follows (in millions):

| Alliant Energy |  |
| 2020 |  | 2019 |  | 2018 |  |  |  |  |  |
Revenues | $801 |  |  | $783 |  |  | $724 |  |  |  |  |  |  |
Operating income | 376 |  |  | 359 |  |  | 325 |  |  |  |  |  |  |
Net income | 343 |  |  | 340 |  |  | 217 |  |  |  |  |  |  |
As of December 31: |  |  |  |  |  |  |  |  |  |  |
Current assets | 121 |  |  | 139 |  |  |  |  |  |  |  |  |
Non-current assets | 6,388 |  |  | 5,964 |  |  |  |  |  |  |  |  |
Current liabilities | 317 |  |  | 507 |  |  |  |  |  |  |  |  |
Non-current liabilities | 2,997 |  |  | 2,659 |  |  |  |  |  |  |  |  |
Noncontrolling interest | 192 |  |  | 208 |  |  |  |  |  |  |  |  |

ATC Holdings - As of December 31, 2020, Alliant Energy has a 16% ownership interest in ATC and a 20% ownership interest in ATC Holdco LLC, collectively referred to as ATC Holdings. ATC is an independent, for-profit, transmission-only company. ATC Holdco LLC holds Duke-American Transmission Company, LLC, a joint venture between Duke Energy Corporation and ATC, that owns electric transmission infrastructure in North America.
Non-utility Wind Farm in Oklahoma - The non-utility wind farm located in Oklahoma provides electricity to a third-party under a long-term PPA, and has both cash and tax equity ownership. The equity income recognized in 2018 was primarily related to the impacts of Federal Tax Reform. The liquidation method utilized to recognize Alliant Energy’s share of the wind farm’s earnings includes utilizing the federal income tax rate in effect as of the end of the measurement period. The lower federal income tax rate effective as of January 1, 2018 resulted in an acceleration of earnings attributable to Alliant Energy’s interest in the Oklahoma wind farm. This increase in earnings is expected to reverse over time. Alliant Energy does not maintain or operate the wind farm, and provided a parent guarantee of its subsidiary’s indemnification obligations under the operating agreement and PPA. Refer to Note 17(d) for discussion of the guarantee.

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NOTE 7. COMMON EQUITY
Common Share Activity - A summary of Alliant Energy’s common stock activity was as follows:

| 2020 |  | 2019 |  | 2018
Shares outstanding, January 1 | 245,022,800 |  |  | 236,063,279 |  |  | 231,348,646 |
Equity forward agreements | 4,275,127 |  |  | 8,358,973 |  |  | — |
At-the-market offering programs | — |  |  | — |  |  | 4,171,013 |
Shareowner Direct Plan | 472,283 |  |  | 501,808 |  |  | 576,965 |
Equity-based compensation plans | 98,205 |  |  | 101,478 |  |  | 5,078 |
Other | — |  |  | (2,738) |  |  | (38,423) |
Shares outstanding, December 31 | 249,868,415 |  |  | 245,022,800 |  |  | 236,063,279 |

At December 31, 2020, Alliant Energy had a total of 15 million shares available for issuance in the aggregate, pursuant to its 2020 OIP, Shareowner Direct Plan and 401(k) Savings Plan.
Equity Forward Agreements - In 2018, Alliant Energy entered into forward sale agreements with various counterparties in connection with a public offering of 8,358,973 shares of Alliant Energy common stock. In 2019, Alliant Energy settled $366 million under the forward sale agreements by delivering 8,358,973 shares of newly issued Alliant Energy common stock at a weighted average forward sale price of $43.75 per share. Alliant Energy used the net proceeds from the settlements for general corporate purposes.
In 2019, Alliant Energy entered into forward sale agreements with a counterparty in connection with a public offering of 4,275,127 shares of Alliant Energy common stock. In 2020, Alliant Energy settled $222 million under the forward sale agreements by delivering 4,275,127 shares of newly issued Alliant Energy common stock at a weighted average forward sale price of $51.98 per share. Alliant Energy used the net proceeds from the settlements for general corporate purposes.
At-the-Market Offering Program - In 2018, Alliant Energy filed a prospectus supplement under which it could sell up to $175 million of its common stock through an at-the-market offering program. In 2018, Alliant Energy issued 4,171,013 shares of common stock through this program and received cash proceeds of $173 million, net of $2 million in commissions and fees. The 2018 at-the-market offering program has expired.
Shareowner Direct Plan - Alliant Energy satisfies its requirements under the Shareowner Direct Plan (dividend reinvestment and stock purchase plan) by acquiring Alliant Energy common stock through original issue, rather than on the open market.
NOTE 8. PREFERRED STOCK
IPL is authorized to issue up to 16,000,000 shares of cumulative preferred stock in aggregate. Information related to the carrying value of IPL’s cumulative preferred stock at December 31 was as follows:

Series |  | Liquidation Preference/Stated Value |  | Shares Authorized |  | Shares Outstanding |  | 2020 |  | 2019
|  |  |  |  |  |  |  | (in millions)
5.1% |  | $25 |  | 8,000,000 |  | 8,000,000 |  | $200 |  |  | $200 |

IPL may, at its option, redeem the 5.1% cumulative preferred stock for cash at a redemption price of $25 per share plus accrued and unpaid dividends up to the redemption date. The current articles of incorporation of IPL contain a provision that grants the holders of its cumulative preferred stock voting rights to elect two members of IPL’s Board of Directors if preferred dividends equal to six or more quarterly dividend requirements (whether or not consecutive) are in arrears. Such voting rights would not provide the holders of IPL’s preferred stock control of the Board of Directors and could not force IPL to redeem its preferred stock.
NOTE 9. DEBT
NOTE 9(a) Short-term Debt - Alliant Energy and its subsidiaries maintain committed bank lines of credit to provide short-term borrowing flexibility and back-stop liquidity for commercial paper outstanding. At December 31, 2020, the short-term borrowing capacity under a single credit facility agreement, which expires in August 2023, totaled $1 billion ($450 million for Alliant Energy at the parent company level, $250 million for IPL and $300 million for WPL). Subject to certain conditions, Alliant Energy (at the parent company level), IPL and WPL may each reallocate and change its sublimit up to $500 million, $400 million and $500 million, respectively, within the $1 billion total commitment. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper, and Alliant Energy’s and WPL’s borrowings under the single credit facility, classified as short-term debt was as follows (dollars in millions):

| Alliant Energy |  | IPL |  | WPL
December 31 | 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Amount outstanding | $389 |  | $337 |  | $— |  | $— |  | $257 |  | $168
Weighted average interest rates | 0.2% |  | 1.9% |  | N/A |  | N/A |  | 0.1% |  | 1.8%
Available credit facility capacity | $611 |  | $663 |  | $250 |  | $250 |  | $43 |  | $132

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| Alliant Energy |  | IPL |  | WPL
For the year ended | 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Maximum amount outstanding (based on daily outstanding balances) | $495 |  | $601 |  | $8 |  | $50 |  | $266 |  | $195
Average amount outstanding (based on daily outstanding balances) | $292 |  | $453 |  | $— |  | $— |  | $117 |  | $93
Weighted average interest rates | 0.7% |  | 2.5% |  | 0.5% |  | 2.8% |  | 0.7% |  | 2.4%

NOTE 9(b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):

| 2020 |  | 2019
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures (a): |  |  |  |  |  |  |  |  |  |  |
3.25%, due 2024 | $500 |  |  | $500 |  |  | $— |  |  | $500 |  |  | $500 |  |  | $— |
3.4%, due 2025 | 250 |  |  | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |
5.5%, due 2025 | 50 |  |  | 50 |  |  | — |  |  | 50 |  |  | 50 |  |  | — |
4.1%, due 2028 | 500 |  |  | 500 |  |  | — |  |  | 500 |  |  | 500 |  |  | — |
3.6%, due 2029 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
2.3%, due 2030 (b) | 400 |  |  | 400 |  |  | — |  |  | — |  |  | — |  |  | — |
6.45%, due 2033 | 100 |  |  | 100 |  |  | — |  |  | 100 |  |  | 100 |  |  | — |
6.3%, due 2034 | 125 |  |  | 125 |  |  | — |  |  | 125 |  |  | 125 |  |  | — |
6.25%, due 2039 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
4.7%, due 2043 | 250 |  |  | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |
3.7%, due 2046 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.5%, due 2049 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.65% (Retired in 2020) | — |  |  | — |  |  | — |  |  | 200 |  |  | 200 |  |  | — |
| 3,375 |  |  | 3,375 |  |  | — |  |  | 3,175 |  |  | 3,175 |  |  | — |
Debentures (a): |  |  |  |  |  |  |  |  |  |  |
2.25%, due 2022 | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |  |  | 250 |
3.05%, due 2027 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
3%, due 2029 | 350 |  |  | — |  |  | 350 |  |  | 350 |  |  | — |  |  | 350 |
6.25%, due 2034 | 100 |  |  | — |  |  | 100 |  |  | 100 |  |  | — |  |  | 100 |
6.375%, due 2037 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
7.6%, due 2038 | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |  |  | 250 |
4.1%, due 2044 | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |  |  | 250 |
3.65%, due 2050 (c) | 350 |  |  | — |  |  | 350 |  |  | — |  |  | — |  |  | — |
4.6% (Retired in 2020) | — |  |  | — |  |  | — |  |  | 150 |  |  | — |  |  | 150 |
| 2,150 |  |  | — |  |  | 2,150 |  |  | 1,950 |  |  | — |  |  | 1,950 |
Other: |  |  |  |  |  |  |  |  |  |  |
AEF term loan credit agreement through March 2022, 1% at December 31, 2020 (with Alliant Energy as guarantor) (d) | 300 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services 3.45% senior notes, due 2022 (a) | 75 |  |  | — |  |  | — |  |  | 75 |  |  | — |  |  | — |
AEF 3.75% senior notes, due 2023 (with Alliant Energy as guarantor) (a) | 400 |  |  | — |  |  | — |  |  | 400 |  |  | — |  |  | — |
AEF 1.4% senior notes, due 2026 (with Alliant Energy as guarantor) (a)(e) | 200 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
AEF 4.25% senior notes, due 2028 (with Alliant Energy as guarantor) (a) | 300 |  |  | — |  |  | — |  |  | 300 |  |  | — |  |  | — |
Sheboygan Power, LLC 5.06% senior secured notes, due 2021 to 2024 (secured by the Sheboygan Falls Energy Facility and related assets) (a) | 31 |  |  | — |  |  | — |  |  | 38 |  |  | — |  |  | — |
AEF term loan credit agreement, 2% at December 31, 2019 (with Alliant Energy as guarantor) (Retired in 2020) | — |  |  | — |  |  | — |  |  | 300 |  |  | — |  |  | — |
Other, 1% at December 31, 2020, due 2021 to 2025 | 2 |  |  | — |  |  | — |  |  | 2 |  |  | — |  |  | — |
| 1,308 |  |  | — |  |  | — |  |  | 1,115 |  |  | — |  |  | — |
Subtotal | 6,833 |  |  | 3,375 |  |  | 2,150 |  |  | 6,240 |  |  | 3,175 |  |  | 1,950 |
Current maturities | (8) |  |  | — |  |  | — |  |  | (657) |  |  | (200) |  |  | (150) |
Unamortized debt issuance costs | (41) |  |  | (22) |  |  | (14) |  |  | (37) |  |  | (21) |  |  | (11) |
Unamortized debt (discount) and premium, net | (15) |  |  | (8) |  |  | (6) |  |  | (13) |  |  | (7) |  |  | (6) |
Long-term debt, net (f) | $6,769 |  |  | $3,345 |  |  | $2,130 |  |  | $5,533 |  |  | $2,947 |  |  | $1,783 |

(a)Contains optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption.

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(b)In June 2020, IPL issued $400 million of 2.3% senior debentures due 2030. The net proceeds from the issuance were used by IPL to retire its $200 million 3.65% senior debentures that would have matured in September 2020 and for general corporate purposes.
(c)In April 2020, WPL issued $350 million of 3.65% debentures due 2050. The net proceeds from the issuance were used by WPL to reduce borrowings under the single credit facility and for general corporate purposes.
(d)In March 2020, AEF entered into a $300 million variable-rate term loan credit agreement and used the borrowings under this agreement to retire its $300 million variable-rate term loan credit agreement that would have expired in April 2020.
(e)In November 2020, AEF issued $200 million of 1.4% senior notes due 2026. The net proceeds from the issuance were used to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes.
(f)There were no significant sinking fund requirements related to the outstanding long-term debt.
Five-Year Schedule of Long-term Debt Maturities - At December 31, 2020, long-term debt maturities for 2021 through 2025 were as follows (in millions):

| 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025
IPL | $— |  | $— |  | $— |  | $500 |  | $300
WPL | — |  | 250 |  | — |  | — |  | —
Corporate Services | — |  | 75 |  | — |  | — |  | —
AEF | 8 |  | 308 |  | 408 |  | 9 |  | —
Alliant Energy | $8 |  | $633 |  | $408 |  | $509 |  | $300

Fair Value of Long-term Debt - Refer to Note 16 for information on the fair value of long-term debt outstanding.
NOTE 10. LEASES
Operating Leases - Alliant Energy’s, IPL’s and WPL’s operating leases primarily include leases of space on telecommunication towers and leases of property. At December 31, operating lease details are as follows (dollars in millions):

| 2020 |  | 2019
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Property, plant and equipment, net | $15 |  | $9 |  | $6 |  | $16 |  | $10 |  | $6
Other current liabilities | $2 |  | $1 |  | $1 |  | $2 |  | $1 |  | $1
Other liabilities | 13 |  | 8 |  | 5 |  | 14 |  | 9 |  | 5
Total operating lease liabilities | $15 |  | $9 |  | $6 |  | $16 |  | $10 |  | $6
Weighted average remaining lease term | 10 years |  | 11 years |  | 9 years |  | 11 years |  | 12 years |  | 10 years
Weighted average discount rate | 4% |  | 4% |  | 4% |  | 4% |  | 4% |  | 4%

Finance Lease - WPL is currently leasing the Sheboygan Falls Energy Facility from AEF’s Non-utility Generation business through 2025, the initial lease term. WPL is responsible for the operation of the EGU and has exclusive rights to its output. This finance lease contains two lease renewal periods, which are not included in the finance lease obligation, as well as an option to purchase the facility at the end of the initial lease term. WPL’s finance lease details are as follows (dollars in millions):

| December 31, 2020 |  | December 31, 2019
Property, plant and equipment, net | $27 |  | $32
Other current liabilities | $9 |  | $9
Finance lease obligations - Sheboygan Falls Energy Facility | 42 |  | 51
Total finance lease liabilities | $51 |  | $60
Remaining lease term | 4 years |  | 5 years
Discount rate | 11% |  | 11%
| 2020 |  | 2019
Depreciation expense | $6 |  | $6
Interest expense | 6 |  | 7
Total finance lease expense | $12 |  | $13

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Expected Maturities - As of December 31, 2020, expected maturities of lease liabilities were as follows (in millions):

| 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025 |  | Thereafter |  | Total |  | Less: amount representing interest |  | Present value of minimum lease payments
Operating Leases: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alliant Energy | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $2 |  |  | $8 |  | $18 |  | $3 |  | $15
IPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 6 |  | 11 |  | 2 |  | 9
WPL | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 1 |  |  | 2 |  | 7 |  | 1 |  | 6
WPL’s Finance Lease: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sheboygan Falls Energy Facility | 15 |  |  | 15 |  |  | 15 |  |  | 15 |  |  | 5 |  |  | — |  | 65 |  | 14 |  | 51

NOTE 11. REVENUES
Revenues from Alliant Energy’s, IPL’s and WPL’s utility businesses are primarily from electric and gas sales provided to customers based on approved tariffs or specific contracts with customers. IPL’s and WPL’s primary performance obligations under such arrangements are to deliver electricity and gas, and their customers simultaneously receive and consume the electricity and gas. For such arrangements, revenues are recognized equivalent to the value of the electricity or gas supplied during each period, including amounts billed during each period and changes in amounts estimated to be billed at the end of each period. IPL and WPL apply the right to invoice method to measure progress towards completing performance obligations to transfer electricity and gas to their customers.
IPL provides retail electric and gas service to customers in Iowa, and WPL provides retail and wholesale electric and retail gas service to customers in Wisconsin. IPL also sells electricity to wholesale customers in Minnesota, Illinois and Iowa, as well as steam from its Prairie Creek Generating Station to high-pressure steam customers in Iowa.
IPL’s and WPL’s retail electric and gas revenues include sales to residential, commercial and industrial customers. IPL’s and WPL’s retail electric and gas customer prices are based on IPL’s and WPL’s cost of service and are determined through general rate review proceedings and various tariff filings with the IUB and PSCW, respectively. Such tariff-based services provide electricity or gas to customers without a defined contractual term.
IPL and WPL have wholesale electric market-based rate authority from FERC allowing them to participate in wholesale energy markets (e.g. MISO) and transact directly with third parties. This authority from FERC allows sales of electricity referred to as bulk power sales based on current market values. FERC also allows IPL and WPL to enter into power supply agreements with municipalities and rural electric cooperatives with defined contractual terms, which include standard pricing mechanisms that are detailed in current tariffs accepted by FERC through wholesale rate review proceedings.
Revenues from Alliant Energy’s non-utility business customers are primarily from its Travero business, which includes a short-line rail freight service in Iowa; a barge, rail and truck freight terminal on the Mississippi River; and freight brokerage and logistics management services.

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Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Electric Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | $1,093 |  |  | $1,092 |  |  | $1,063 |  |  | $602 |  |  | $601 |  |  | $590 |  |  | $491 |  |  | $491 |  |  | $473 |
Retail - commercial | 718 |  |  | 770 |  |  | 736 |  |  | 474 |  |  | 510 |  |  | 487 |  |  | 244 |  |  | 260 |  |  | 249 |
Retail - industrial | 841 |  |  | 889 |  |  | 889 |  |  | 488 |  |  | 504 |  |  | 501 |  |  | 353 |  |  | 385 |  |  | 388 |
Wholesale | 168 |  |  | 177 |  |  | 188 |  |  | 57 |  |  | 64 |  |  | 71 |  |  | 111 |  |  | 113 |  |  | 117 |
Bulk power and other | 100 |  |  | 136 |  |  | 124 |  |  | 74 |  |  | 102 |  |  | 82 |  |  | 26 |  |  | 34 |  |  | 42 |
Total Electric Utility | 2,920 |  |  | 3,064 |  |  | 3,000 |  |  | 1,695 |  |  | 1,781 |  |  | 1,731 |  |  | 1,225 |  |  | 1,283 |  |  | 1,269 |
Gas Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | 214 |  |  | 259 |  |  | 254 |  |  | 116 |  |  | 149 |  |  | 152 |  |  | 98 |  |  | 110 |  |  | 102 |
Retail - commercial | 107 |  |  | 133 |  |  | 133 |  |  | 59 |  |  | 75 |  |  | 76 |  |  | 48 |  |  | 58 |  |  | 57 |
Retail - industrial | 12 |  |  | 16 |  |  | 15 |  |  | 8 |  |  | 12 |  |  | 10 |  |  | 4 |  |  | 4 |  |  | 5 |
Transportation/other | 40 |  |  | 47 |  |  | 45 |  |  | 25 |  |  | 28 |  |  | 28 |  |  | 15 |  |  | 19 |  |  | 17 |
Total Gas Utility | 373 |  |  | 455 |  |  | 447 |  |  | 208 |  |  | 264 |  |  | 266 |  |  | 165 |  |  | 191 |  |  | 181 |
Other Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Steam | 36 |  |  | 37 |  |  | 35 |  |  | 36 |  |  | 37 |  |  | 35 |  |  | — |  |  | — |  |  | — |
Other utility | 13 |  |  | 9 |  |  | 13 |  |  | 8 |  |  | 7 |  |  | 10 |  |  | 5 |  |  | 2 |  |  | 3 |
Total Other Utility | 49 |  |  | 46 |  |  | 48 |  |  | 44 |  |  | 44 |  |  | 45 |  |  | 5 |  |  | 2 |  |  | 3 |
Non-Utility and Other: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Travero and other | 74 |  |  | 83 |  |  | 39 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total Non-Utility and Other | 74 |  |  | 83 |  |  | 39 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total revenues | $3,416 |  |  | $3,648 |  |  | $3,534 |  |  | $1,947 |  |  | $2,089 |  |  | $2,042 |  |  | $1,395 |  |  | $1,476 |  |  | $1,453 |

NOTE 12. INCOME TAXES
Income Tax Expense (Benefit) - The components of “Income tax expense (benefit)” in the income statements were as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Current tax expense (benefit): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Federal | $1 |  |  | ($7) |  |  | ($1) |  |  | $6 |  |  | ($11) |  |  | $15 |  |  | ($11) |  |  | $12 |  |  | ($9) |
State | 8 |  |  | 24 |  |  | (5) |  |  | (1) |  |  | 24 |  |  | (7) |  |  | 7 |  |  | 13 |  |  | (5) |
IPL’s tax benefit riders | — |  |  | (4) |  |  | (13) |  |  | — |  |  | (4) |  |  | (13) |  |  | — |  |  | — |  |  | — |
Deferred tax expense (benefit): |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Federal | 22 |  |  | 70 |  |  | 68 |  |  | 30 |  |  | 26 |  |  | 10 |  |  | (9) |  |  | 31 |  |  | 44 |
State | 8 |  |  | 42 |  |  | 30 |  |  | (2) |  |  | 31 |  |  | 7 |  |  | 10 |  |  | 6 |  |  | 22 |
Production tax credits | (95) |  |  | (55) |  |  | (30) |  |  | (80) |  |  | (42) |  |  | (14) |  |  | (15) |  |  | (13) |  |  | (15) |
Investment tax credits | (1) |  |  | (1) |  |  | (1) |  |  | — |  |  | — |  |  | (1) |  |  | (1) |  |  | — |  |  | (1) |
| ($57) |  |  | $69 |  |  | $48 |  |  | ($47) |  |  | $24 |  |  | ($3) |  |  | ($19) |  |  | $49 |  |  | $36 |

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Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Statutory federal income tax rate | 21 | % |  | 21 | % |  | 21 | % |  | 21 | % |  | 21 | % |  | 21 | % |  | 21 | % |  | 21 | % |  | 21 | %
State income taxes, net of federal benefits | 2 |  |  | 7 |  |  | 7 |  |  | (1) |  |  | 8 |  |  | 8 |  |  | 6 |  |  | 6 |  |  | 6 |
Production tax credits | (17) |  |  | (9) |  |  | (5) |  |  | (28) |  |  | (13) |  |  | (5) |  |  | (7) |  |  | (5) |  |  | (7) |
Amortization of excess deferred taxes (Refer to Note 2) | (13) |  |  | (1) |  |  | (1) |  |  | (5) |  |  | — |  |  | — |  |  | (26) |  |  | (2) |  |  | — |
Effect of rate-making on property-related differences | (3) |  |  | (6) |  |  | (8) |  |  | (4) |  |  | (10) |  |  | (14) |  |  | (2) |  |  | (3) |  |  | (2) |
Adjustment for prior period taxes | 1 |  |  | 1 |  |  | (2) |  |  | 1 |  |  | 3 |  |  | (5) |  |  | — |  |  | — |  |  | — |
IPL’s tax benefit riders | — |  |  | (1) |  |  | (2) |  |  | — |  |  | (1) |  |  | (5) |  |  | — |  |  | — |  |  | — |
Federal Tax Reform adjustments | — |  |  | — |  |  | (1) |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (2) |
Other items, net | (1) |  |  | (1) |  |  | (1) |  |  | — |  |  | — |  |  | (1) |  |  | — |  |  | — |  |  | (1) |
Overall income tax rate | (10 | %) |  | 11 | % |  | 8 | % |  | (16 | %) |  | 8 | % |  | (1 | %) |  | (8 | %) |  | 17 | % |  | 15 | %

Deferred Tax Assets and Liabilities - The deferred tax assets and liabilities included on the balance sheets at December 31 arise from the following temporary differences (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Deferred tax liabilities: |  |  |  |  |  |  |  |  |  |  |
Property | $2,232 |  |  | $2,022 |  |  | $1,312 |  |  | $1,184 |  |  | $854 |  |  | $770 |
ATC Holdings | 116 |  |  | 111 |  |  | — |  |  | — |  |  | — |  |  | — |
Other | 101 |  |  | 84 |  |  | 83 |  |  | 76 |  |  | 41 |  |  | 32 |
Total deferred tax liabilities | 2,449 |  |  | 2,217 |  |  | 1,395 |  |  | 1,260 |  |  | 895 |  |  | 802 |
Deferred tax assets: |  |  |  |  |  |  |  |  |  |  |
Federal credit carryforwards | 454 |  |  | 355 |  |  | 258 |  |  | 175 |  |  | 175 |  |  | 160 |
Net operating losses carryforwards - federal | 77 |  |  | 60 |  |  | 71 |  |  | 56 |  |  | 1 |  |  | 1 |
Net operating losses carryforwards - state | 37 |  |  | 37 |  |  | 1 |  |  | 1 |  |  | — |  |  | — |
Other | 73 |  |  | 61 |  |  | 30 |  |  | 20 |  |  | 18 |  |  | 16 |
Subtotal deferred tax assets | 641 |  |  | 513 |  |  | 360 |  |  | 252 |  |  | 194 |  |  | 177 |
Valuation allowances | (6) |  |  | (10) |  |  | — |  |  | — |  |  | (1) |  |  | (1) |
Total deferred tax assets | 635 |  |  | 503 |  |  | 360 |  |  | 252 |  |  | 193 |  |  | 176 |
Total deferred tax liabilities, net | $1,814 |  |  | $1,714 |  |  | $1,035 |  |  | $1,008 |  |  | $702 |  |  | $626 |

Carryforwards - At December 31, 2020, carryforwards and expiration dates were estimated as follows (in millions):

| Range of Expiration Dates |  | Alliant Energy |  | IPL |  | WPL
Federal net operating losses | 2037 |  | $366 |  | $339 |  | $3
State net operating losses | 2021-2040 |  | 622 |  | 10 |  | 2
Federal tax credits | 2022-2040 |  | 454 |  | 258 |  | 175

Valuation Allowances - Alliant Energy currently expects its federal net operating losses carryforwards will not be fully utilized until 2023. Because taxable income must be reduced by federal net operating losses carryforwards prior to utilizing federal tax credit carryforwards, Alliant Energy currently does not expect to utilize 2002 vintage federal credit carryforwards prior to their expiration in 2022, resulting in valuation allowances that remain as of December 31, 2020. Alliant Energy currently expects to be able to utilize 2003 vintage federal credit carryforwards prior to their expiration in 2023, and as a result, in 2020, Alliant Energy reversed $4 million of previously recorded valuation allowances related to these federal credit carryforwards.
Uncertain Tax Positions - At December 31, 2020, 2019 and 2018, there were no uncertain tax positions or penalties accrued related to uncertain tax positions. As of December 31, 2020, no material changes to unrecognized tax benefits are expected during the next 12 months.

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Open tax years - Tax years that remain subject to the statute of limitations in the major jurisdictions for each of Alliant Energy, IPL and WPL are as follows:

Consolidated federal income tax returns (a) | 2017 | - | 2019
Consolidated Iowa income tax returns (b) | 2017 | - | 2019
Wisconsin combined tax returns (c) | 2016 | - | 2019

(a)The 2017 federal tax return is effectively settled as a result of participation in the IRS Compliance Assurance Program, which allows Alliant Energy and the IRS to work together to resolve issues related to Alliant Energy’s current tax year before filing its federal income tax return. The statute of limitations for these federal tax returns expires three years from each filing date.
(b)The statute of limitations for these Iowa tax returns expires three years from each filing date.
(c)The statute of limitations for these Wisconsin combined tax returns expires four years from each filing date.
Federal Tax Reform Adjustments - In 2018, additional rules were issued related to Federal Tax Reform, including clarifications of the treatment of bonus depreciation deductions, which impacted the federal income tax return for the calendar year 2017. As a result of these clarifying rules, Alliant Energy, IPL and WPL recorded tax benefits of $6 million, $1 million and $5 million, respectively, in 2018.
Iowa Tax Reform - In 2018, Iowa tax reform was enacted, resulting in a reduction in the Iowa income tax rate from 12% to 9.8%, effective January 1, 2021, and the elimination of the deduction for federal income taxes, effective January 1, 2022, for taxes related to 2020 and prior.
NOTE 13. BENEFIT PLANS
NOTE 13(a) Pension and Other Postretirement Benefits Plans - Retirement benefits are provided to substantially all employees through various qualified and non-qualified non-contributory defined benefit pension plans (currently closed to new hires), and/or through defined contribution plans (including 401(k) savings plans). Benefits of the non-contributory defined benefit pension plans are based on the plan participant’s years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participant’s years of service, age, compensation and contributions. Certain defined benefit postretirement health care and life benefits are provided to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory.
IPL and WPL account for their participation in Alliant Energy and Corporate Services sponsored plans as multiple-employer plans. For IPL and WPL, amounts below represent the amounts for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.
Assumptions - The assumptions for defined benefit pension and OPEB plans at the measurement date of December 31 were as follows:

| Defined Benefit Pension Plans |  | OPEB Plans
Alliant Energy | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Discount rate for benefit obligations | 2.57% |  | 3.48% |  | 4.34% |  | 2.31% |  | 3.40% |  | 4.24%
Discount rate for net periodic cost | 3.48% |  | 4.34% |  | 3.66% |  | 3.40% |  | 4.24% |  | 3.53%
Expected rate of return on plan assets | 7.10% |  | 7.60% |  | 7.60% |  | 4.50% |  | 5.44% |  | 5.44%
Interest crediting rate for Alliant Energy Cash Balance Pension Plan | 4.76% |  | 5.52% |  | 5.04% |  | N/A |  | N/A |  | N/A
Rate of compensation increase | 3.65% | - | 4.50% |  | 3.65% | - | 4.50% |  | 3.65% | - | 4.50% |  | N/A |  | N/A |  | N/A

| Qualified Defined Benefit Pension Plan |  | OPEB Plans
IPL | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Discount rate for benefit obligations | 2.61% |  | 3.51% |  | 4.35% |  | 2.28% |  | 3.39% |  | 4.23%
Discount rate for net periodic cost | 3.51% |  | 4.35% |  | 3.68% |  | 3.39% |  | 4.23% |  | 3.51%
Expected rate of return on plan assets | 7.10% |  | 7.60% |  | 7.60% |  | 4.50% |  | 5.60% |  | 5.60%
Rate of compensation increase | 3.65% |  | 3.65% |  | 3.65% |  | N/A |  | N/A |  | N/A

| Qualified Defined Benefit Pension Plan |  | OPEB Plans
WPL | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Discount rate for benefit obligations | 2.64% |  | 3.50% |  | 4.35% |  | 2.27% |  | 3.39% |  | 4.23%
Discount rate for net periodic cost | 3.50% |  | 4.35% |  | 3.69% |  | 3.39% |  | 4.23% |  | 3.51%
Expected rate of return on plan assets | 7.10% |  | 7.60% |  | 7.60% |  | 3.28% |  | 3.81% |  | 3.84%
Rate of compensation increase | 3.65% |  | 3.65% |  | 3.65% |  | N/A |  | N/A |  | N/A

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Expected rate of return on plan assets - The expected rate of return on plan assets is based on projected asset class returns using target allocations. A forward-looking building blocks approach is used, and historical returns, survey information and capital market information are analyzed to support the expected rate of return on plan assets assumption. Refer to “Investment Strategy for Plan Assets” below for additional information related to investment strategy and mix of assets for the pension and OPEB plans.
Life Expectancy - The life expectancy assumption is used in determining the benefit obligation and net periodic benefit cost for defined benefit pension and OPEB plans. This assumption utilizes base mortality tables that were released in 2019 by the Society of Actuaries and mortality projection tables that were released in 2020 by the Society of Actuaries.
Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans are included below (in millions). The service cost component of net periodic benefit costs is included in “Other operation and maintenance” expenses in the income statements and all other components of net periodic benefit costs are included in “Other (income) and deductions” in the income statements.

Alliant Energy | Defined Benefit Pension Plans |  | OPEB Plans
2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Service cost | $11 |  |  | $10 |  |  | $12 |  |  | $3 |  |  | $3 |  |  | $4 |
Interest cost | 43 |  |  | 50 |  |  | 47 |  |  | 7 |  |  | 9 |  |  | 8 |
Expected return on plan assets (a) | (70) |  |  | (60) |  |  | (69) |  |  | (5) |  |  | (5) |  |  | (6) |
Amortization of prior service credit (b) | — |  |  | (1) |  |  | (1) |  |  | — |  |  | — |  |  | — |
Amortization of actuarial loss (c) | 34 |  |  | 36 |  |  | 35 |  |  | 3 |  |  | 3 |  |  | 3 |
Settlement losses (d) | 12 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
| $30 |  |  | $35 |  |  | $24 |  |  | $8 |  |  | $10 |  |  | $9 |

IPL | Defined Benefit Pension Plans |  | OPEB Plans
2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Service cost | $7 |  |  | $6 |  |  | $7 |  |  | $1 |  |  | $1 |  |  | $2 |
Interest cost | 20 |  |  | 23 |  |  | 21 |  |  | 3 |  |  | 3 |  |  | 3 |
Expected return on plan assets (a) | (33) |  |  | (28) |  |  | (32) |  |  | (4) |  |  | (4) |  |  | (4) |
Amortization of actuarial loss (c) | 15 |  |  | 15 |  |  | 15 |  |  | 1 |  |  | 2 |  |  | 1 |
Settlement losses (d) | 7 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
| $16 |  |  | $16 |  |  | $11 |  |  | $1 |  |  | $2 |  |  | $2 |

WPL | Defined Benefit Pension Plans |  | OPEB Plans
2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Service cost | $4 |  |  | $3 |  |  | $4 |  |  | $2 |  |  | $1 |  |  | $2 |
Interest cost | 19 |  |  | 21 |  |  | 20 |  |  | 3 |  |  | 3 |  |  | 3 |
Expected return on plan assets (a) | (31) |  |  | (26) |  |  | (30) |  |  | (1) |  |  | (1) |  |  | (1) |
Amortization of prior service credit (b) | — |  |  | — |  |  | — |  |  | (1) |  |  | — |  |  | — |
Amortization of actuarial loss (c) | 16 |  |  | 18 |  |  | 17 |  |  | 2 |  |  | 2 |  |  | 2 |
| $8 |  |  | $16 |  |  | $11 |  |  | $5 |  |  | $5 |  |  | $6 |

(a)The expected return on plan assets is based on the expected rate of return on plan assets and the fair value approach to the market-related value of plan assets.
(b)Unrecognized prior service credits for the OPEB plans are amortized over the average future service period to full eligibility of the participants of each plan.
(c)Unrecognized net actuarial gains or losses in excess of 10% of the greater of the plans’ benefit obligations or assets are amortized over the average future service lives of plan participants, except for the Alliant Energy Cash Balance Pension Plan where gains or losses outside the 10% threshold are amortized over the time period the participants are expected to receive benefits.
(d)Settlement losses related to payments made to retired executives of Alliant Energy and lump sum payments related to IPL’s qualified defined benefit pension plan.

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Benefit Plan Assets and Obligations - A reconciliation of the funded status of qualified and non-qualified defined benefit pension and OPEB plans to the amounts recognized on the balance sheets at December 31 was as follows (in millions):

| Defined Benefit Pension Plans |  | OPEB Plans
Alliant Energy | 2020 |  | 2019 |  | 2020 |  | 2019
Change in benefit obligation: |  |  |  |  |  |  |
Net benefit obligation at January 1 | $1,280 |  |  | $1,175 |  |  | $214 |  |  | $206 |
Service cost | 11 |  |  | 10 |  |  | 3 |  |  | 3 |
Interest cost | 43 |  |  | 50 |  |  | 7 |  |  | 9 |
Plan participants’ contributions | — |  |  | — |  |  | 4 |  |  | 3 |
Actuarial loss | 132 |  |  | 124 |  |  | 18 |  |  | 14 |
Gross benefits paid | (115) |  |  | (79) |  |  | (19) |  |  | (21) |
Net benefit obligation at December 31 | 1,351 |  |  | 1,280 |  |  | 227 |  |  | 214 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 931 |  |  | 809 |  |  | 105 |  |  | 99 |
Actual return on plan assets | 108 |  |  | 168 |  |  | 11 |  |  | 15 |
Employer contributions | 60 |  |  | 33 |  |  | 7 |  |  | 9 |
Plan participants’ contributions | — |  |  | — |  |  | 4 |  |  | 3 |
Gross benefits paid | (115) |  |  | (79) |  |  | (19) |  |  | (21) |
Fair value of plan assets at December 31 | 984 |  |  | 931 |  |  | 108 |  |  | 105 |
Under funded status at December 31 | ($367) |  |  | ($349) |  |  | ($119) |  |  | ($109) |

| Defined Benefit Pension Plans |  | OPEB Plans
Alliant Energy | 2020 |  | 2019 |  | 2020 |  | 2019
Amounts recognized on the balance sheets consist of: |  |  |  |  |  |  |
Non-current assets | $— |  |  | $— |  |  | $8 |  |  | $10 |
Current liabilities | (2) |  |  | (14) |  |  | (8) |  |  | (8) |
Pension and other benefit obligations | (365) |  |  | (335) |  |  | (119) |  |  | (111) |
Net amounts recognized at December 31 | ($367) |  |  | ($349) |  |  | ($119) |  |  | ($109) |
Amounts recognized in Regulatory Assets consist of: |  |  |  |  |  |  |
Net actuarial loss | $533 |  |  | $485 |  |  | $54 |  |  | $45 |
Prior service credit | (5) |  |  | (5) |  |  | (1) |  |  | (1) |
| $528 |  |  | $480 |  |  | $53 |  |  | $44 |

| Defined Benefit Pension Plans |  | OPEB Plans
IPL | 2020 |  | 2019 |  | 2020 |  | 2019
Change in benefit obligation: |  |  |  |  |  |  |
Net benefit obligation at January 1 | $581 |  |  | $534 |  |  | $86 |  |  | $83 |
Service cost | 7 |  |  | 6 |  |  | 1 |  |  | 1 |
Interest cost | 20 |  |  | 23 |  |  | 3 |  |  | 3 |
Plan participants’ contributions | — |  |  | — |  |  | 1 |  |  | 1 |
Actuarial loss | 60 |  |  | 56 |  |  | 8 |  |  | 6 |
Gross benefits paid | (53) |  |  | (38) |  |  | (8) |  |  | (8) |
Net benefit obligation at December 31 | 615 |  |  | 581 |  |  | 91 |  |  | 86 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 436 |  |  | 378 |  |  | 72 |  |  | 67 |
Actual return on plan assets | 51 |  |  | 79 |  |  | 7 |  |  | 10 |
Employer contributions | 19 |  |  | 17 |  |  | 2 |  |  | 2 |
Plan participants’ contributions | — |  |  | — |  |  | 1 |  |  | 1 |
Gross benefits paid | (53) |  |  | (38) |  |  | (8) |  |  | (8) |
Fair value of plan assets at December 31 | 453 |  |  | 436 |  |  | 74 |  |  | 72 |
Under funded status at December 31 | ($162) |  |  | ($145) |  |  | ($17) |  |  | ($14) |

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| Defined Benefit Pension Plans |  | OPEB Plans
IPL | 2020 |  | 2019 |  | 2020 |  | 2019
Amounts recognized on the balance sheets consist of: |  |  |  |  |  |  |
Non-current assets | $— |  |  | $— |  |  | $4 |  |  | $7 |
Current liabilities | (1) |  |  | (1) |  |  | (2) |  |  | (2) |
Pension and other benefit obligations | (161) |  |  | (144) |  |  | (19) |  |  | (19) |
Net amounts recognized at December 31 | ($162) |  |  | ($145) |  |  | ($17) |  |  | ($14) |
Amounts recognized in Regulatory Assets consist of: |  |  |  |  |  |  |
Net actuarial loss | $228 |  |  | $208 |  |  | $20 |  |  | $17 |
Prior service credit | (1) |  |  | (1) |  |  | — |  |  | — |
| $227 |  |  | $207 |  |  | $20 |  |  | $17 |

| Defined Benefit Pension Plans |  | OPEB Plans
WPL | 2020 |  | 2019 |  | 2020 |  | 2019
Change in benefit obligation: |  |  |  |  |  |  |
Net benefit obligation at January 1 | $550 |  |  | $507 |  |  | $85 |  |  | $83 |
Service cost | 4 |  |  | 3 |  |  | 2 |  |  | 1 |
Interest cost | 19 |  |  | 21 |  |  | 3 |  |  | 3 |
Plan participants’ contributions | — |  |  | — |  |  | 2 |  |  | 2 |
Actuarial loss | 55 |  |  | 54 |  |  | 5 |  |  | 5 |
Gross benefits paid | (40) |  |  | (35) |  |  | (8) |  |  | (9) |
Net benefit obligation at December 31 | 588 |  |  | 550 |  |  | 89 |  |  | 85 |
Change in plan assets: |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 406 |  |  | 352 |  |  | 17 |  |  | 17 |
Actual return on plan assets | 48 |  |  | 73 |  |  | 2 |  |  | 1 |
Employer contributions | 22 |  |  | 16 |  |  | 5 |  |  | 6 |
Plan participants’ contributions | — |  |  | — |  |  | 2 |  |  | 2 |
Gross benefits paid | (40) |  |  | (35) |  |  | (8) |  |  | (9) |
Fair value of plan assets at December 31 | 436 |  |  | 406 |  |  | 18 |  |  | 17 |
Under funded status at December 31 | ($152) |  |  | ($144) |  |  | ($71) |  |  | ($68) |

| Defined Benefit Pension Plans |  | OPEB Plans
WPL | 2020 |  | 2019 |  | 2020 |  | 2019
Amounts recognized on the balance sheets consist of: |  |  |  |  |  |  |
Non-current assets | $— |  |  | $— |  |  | $3 |  |  | $3 |
Current liabilities | — |  |  | — |  |  | (6) |  |  | (6) |
Pension and other benefit obligations | (152) |  |  | (144) |  |  | (68) |  |  | (65) |
Net amounts recognized at December 31 | ($152) |  |  | ($144) |  |  | ($71) |  |  | ($68) |
Amounts recognized in Regulatory Assets consist of: |  |  |  |  |  |  |
Net actuarial loss | $233 |  |  | $212 |  |  | $25 |  |  | $22 |
Prior service credit | (1) |  |  | (1) |  |  | (1) |  |  | (1) |
| $232 |  |  | $211 |  |  | $24 |  |  | $21 |

Actuarial losses related to benefit obligations in 2020 for defined benefit pension and OPEB plans were primarily due to decreases in the discount rates, partially offset by the impact of updated mortality projection tables. Actuarial losses related to benefit obligations in 2019 for defined benefit pension and OPEB plans were primarily due to decreases in the discount rates and experience losses, partially offset by the impact of the updated base mortality table.

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Accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and OPEB plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the December 31 measurement date are as follows (in millions):

| Defined Benefit Pension Plans |  | OPEB Plans
Alliant Energy | 2020 |  | 2019 |  | 2020 |  | 2019
Accumulated benefit obligations | $1,305 |  |  | $1,234 |  |  | $227 |  |  | $214 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 1,305 |  |  | 1,234 |  |  | 227 |  |  | 214 |
Fair value of plan assets | 984 |  |  | 931 |  |  | 108 |  |  | 105 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 1,351 |  |  | 1,280 |  |  | N/A |  | N/A
Fair value of plan assets | 984 |  |  | 931 |  |  | N/A |  | N/A

| Defined Benefit Pension Plans |  | OPEB Plans
IPL | 2020 |  | 2019 |  | 2020 |  | 2019
Accumulated benefit obligations | $589 |  |  | $558 |  |  | $91 |  |  | $86 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 589 |  |  | 558 |  |  | 91 |  |  | 86 |
Fair value of plan assets | 453 |  |  | 436 |  |  | 74 |  |  | 72 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 615 |  |  | 581 |  |  | N/A |  | N/A
Fair value of plan assets | 453 |  |  | 436 |  |  | N/A |  | N/A

| Defined Benefit Pension Plans |  | OPEB Plans
WPL | 2020 |  | 2019 |  | 2020 |  | 2019
Accumulated benefit obligations | $573 |  |  | $536 |  |  | $89 |  |  | $85 |
Plans with accumulated benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Accumulated benefit obligations | 573 |  |  | 536 |  |  | 89 |  |  | 85 |
Fair value of plan assets | 436 |  |  | 406 |  |  | 18 |  |  | 17 |
Plans with projected benefit obligations in excess of plan assets: |  |  |  |  |  |  |
Projected benefit obligations | 588 |  |  | 550 |  |  | N/A |  | N/A
Fair value of plan assets | 436 |  |  | 406 |  |  | N/A |  | N/A

In addition to the amounts recognized in regulatory assets in the above tables for IPL and WPL, regulatory assets were recognized for amounts associated with Corporate Services employees participating in other Alliant Energy sponsored benefit plans that were allocated to IPL and WPL at December 31 as follows (in millions):

| IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019
Regulatory assets | $44 |  | $39 |  | $34 |  | $29

Estimated Future Employer Contributions and Benefit Payments - Estimated funding for the qualified and non-qualified defined benefit pension and OPEB plans for 2021 is as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
Defined benefit pension plans (a) | $39 |  | $17 |  | $18
OPEB plans | 8 |  | 2 |  | 6

(a)Alliant Energy sponsors several non-qualified defined benefit pension plans that cover certain current and former key employees of IPL and WPL. Alliant Energy allocates pension costs to IPL and WPL for these plans. In addition, IPL and WPL amounts reflect funding for their non-bargaining employees who are participants in the Alliant Energy and Corporate Services sponsored qualified and non-qualified defined benefit pension plans.
Expected benefit payments for the qualified and non-qualified defined benefit plans, which reflect expected future service, as appropriate, are as follows (in millions):

Alliant Energy | 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 - 2030
Defined benefit pension benefits | $76 |  |  | $78 |  |  | $79 |  |  | $79 |  |  | $80 |  |  | $398
OPEB | 18 |  |  | 18 |  |  | 17 |  |  | 17 |  |  | 17 |  |  | 74
| $94 |  |  | $96 |  |  | $96 |  |  | $96 |  |  | $97 |  |  | $472

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IPL | 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 - 2030
Defined benefit pension benefits | $38 |  |  | $38 |  |  | $39 |  |  | $38 |  |  | $38 |  |  | $181
OPEB | 7 |  |  | 7 |  |  | 7 |  |  | 7 |  |  | 7 |  |  | 29
| $45 |  |  | $45 |  |  | $46 |  |  | $45 |  |  | $45 |  |  | $210

WPL | 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025 |  | 2026 - 2030
Defined benefit pension benefits | $32 |  |  | $32 |  |  | $32 |  |  | $33 |  |  | $33 |  |  | $162
OPEB | 7 |  |  | 7 |  |  | 7 |  |  | 7 |  |  | 6 |  |  | 29
| $39 |  |  | $39 |  |  | $39 |  |  | $40 |  |  | $39 |  |  | $191

Investment Strategy for Plan Assets - Investment strategies for defined benefit pension and OPEB plan assets combine preservation of principal and prudent risk-taking to protect the integrity of plan assets, in order to meet the obligations to plan participants while minimizing benefit costs over the long term. Investment risk of plan assets is mitigated through diversification, including U.S. and international equity, fixed income, global asset and risk parity strategies. Global asset and risk parity strategies may include investments in global equity, global debt, commodities and currencies.
Defined Benefit Pension Plan Assets - The asset mix of defined benefit pension plans is governed by allocation targets. The asset allocation is monitored regularly, and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. An overlay management service is also used to help maintain target allocations and meet liquidity needs. The overlay manager is authorized to use derivative financial instruments to facilitate this service. For separately managed accounts, prohibited investments include, but are not limited to, direct ownership of real estate, oil and gas limited partnerships, securities of the managers’ firms or affiliate firms, and Alliant Energy securities. At December 31, 2020, the current target ranges and actual allocations for the defined benefit pension plan assets were as follows:

| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | 0% | - | 5% |  | 5%
Equity securities - U.S. | 11% | - | 41% |  | 26%
Equity securities - international | 14% | - | 34% |  | 23%
Global asset securities | 5% | - | 15% |  | 9%
Risk parity securities | 5% | - | 15% |  | 9%
Fixed income securities | 20% | - | 40% |  | 28%

Other Postretirement Benefits Plan Assets - OPEB plan assets are comprised of specific assets within certain defined benefit pension plans (401(h) assets) as well as assets held in VEBA trusts. The investment strategy of the Corporate Services 401(h) assets mirrors those of the defined benefit pension plans, which are discussed above. For VEBA trusts with assets greater than $5 million and the WPL 401(h) assets, the mix among asset classes is governed by allocation targets. The asset allocation is monitored regularly, and appropriate steps are taken as needed to rebalance the assets within the prescribed ranges. At December 31, 2020, the current target ranges and actual allocations for VEBA trusts with assets greater than $5 million and the WPL 401(h) assets were as follows:

| Target Range |  | Actual
| Allocation |  | Allocation
Cash and equivalents | 0% | - | 5% |  | 1%
Equity securities - U.S. | 0% | - | 46% |  | 25%
Equity securities - international | 0% | - | 34% |  | 1%
Fixed income securities | 20% | - | 100% |  | 73%

Fair Value Measurements - Fair value measurement accounting establishes three levels of fair value hierarchy that prioritize the inputs to valuation techniques used to measure fair value. Refer to Note 16 for discussion of levels within the fair value hierarchy. Level 1 items include investments in securities held in registered investment companies and directly held equity securities, which are valued at the closing price reported in the active market in which the securities are traded. Level 2 items include fixed income securities consisting of corporate and government bonds, which are valued at the closing price reported in the active market for similar assets in which the individual securities are traded or based on yields currently available on comparable securities of issuers with similar credit ratings. Certain investments that are measured at fair value using the net asset value practical expedient have not been classified in the fair value hierarchy. These fair value amounts are included below to reconcile the fair value hierarchy to the respective total plan assets.

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At December 31, the fair values of qualified and non-qualified defined benefit pension plan assets were as follows (in millions):

| 2020 |  | 2019
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
Alliant Energy | Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents | $46 |  |  | $— |  |  | $46 |  |  | $— |  |  | $46 |  |  | $4 |  |  | $42 |  |  | $— |
Equity securities - U.S. | 182 |  |  | 182 |  |  | — |  |  | — |  |  | 161 |  |  | 161 |  |  | — |  |  | — |
Equity securities - international | 151 |  |  | 151 |  |  | — |  |  | — |  |  | 136 |  |  | 136 |  |  | — |  |  | — |
Global asset securities | 45 |  |  | 45 |  |  | — |  |  | — |  |  | 47 |  |  | 47 |  |  | — |  |  | — |
Fixed income securities | 134 |  |  | 56 |  |  | 78 |  |  | — |  |  | 131 |  |  | 58 |  |  | 73 |  |  | — |
Total assets in fair value hierarchy | 558 |  |  | $434 |  |  | $124 |  |  | $— |  |  | 521 |  |  | $406 |  |  | $115 |  |  | $— |
Assets measured at net asset value | 426 |  |  |  |  |  |  |  |  | 410 |  |  |  |  |  |  |
Accrued investment income | 1 |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |
Due to brokers, net (pending trades with brokers) | (1) |  |  |  |  |  |  |  |  | (1) |  |  |  |  |  |  |
Total pension plan assets | $984 |  |  |  |  |  |  |  |  | $931 |  |  |  |  |  |  |

| 2020 |  | 2019
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
IPL | Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents | $21 |  |  | $— |  |  | $21 |  |  | $— |  |  | $22 |  |  | $2 |  |  | $20 |  |  | $— |
Equity securities - U.S. | 84 |  |  | 84 |  |  | — |  |  | — |  |  | 75 |  |  | 75 |  |  | — |  |  | — |
Equity securities - international | 69 |  |  | 69 |  |  | — |  |  | — |  |  | 64 |  |  | 64 |  |  | — |  |  | — |
Global asset securities | 21 |  |  | 21 |  |  | — |  |  | — |  |  | 22 |  |  | 22 |  |  | — |  |  | — |
Fixed income securities | 62 |  |  | 26 |  |  | 36 |  |  | — |  |  | 61 |  |  | 27 |  |  | 34 |  |  | — |
Total assets in fair value hierarchy | 257 |  |  | $200 |  |  | $57 |  |  | $— |  |  | 244 |  |  | $190 |  |  | $54 |  |  | $— |
Assets measured at net asset value | 196 |  |  |  |  |  |  |  |  | 192 |  |  |  |  |  |  |
Total pension plan assets | $453 |  |  |  |  |  |  |  |  | $436 |  |  |  |  |  |  |

| 2020 |  | 2019
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
WPL | Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents | $20 |  |  | $— |  |  | $20 |  |  | $— |  |  | $20 |  |  | $2 |  |  | $18 |  |  | $— |
Equity securities - U.S. | 81 |  |  | 81 |  |  | — |  |  | — |  |  | 70 |  |  | 70 |  |  | — |  |  | — |
Equity securities - international | 67 |  |  | 67 |  |  | — |  |  | — |  |  | 59 |  |  | 59 |  |  | — |  |  | — |
Global asset securities | 20 |  |  | 20 |  |  | — |  |  | — |  |  | 21 |  |  | 21 |  |  | — |  |  | — |
Fixed income securities | 59 |  |  | 25 |  |  | 34 |  |  | — |  |  | 57 |  |  | 25 |  |  | 32 |  |  | — |
Total assets in fair value hierarchy | 247 |  |  | $193 |  |  | $54 |  |  | $— |  |  | 227 |  |  | $177 |  |  | $50 |  |  | $— |
Assets measured at net asset value | 189 |  |  |  |  |  |  |  |  | 179 |  |  |  |  |  |  |
Total pension plan assets | $436 |  |  |  |  |  |  |  |  | $406 |  |  |  |  |  |  |

At December 31, the fair values of OPEB plan assets were as follows (in millions):

| 2020 |  | 2019
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
Alliant Energy | Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents | $2 |  |  | $— |  |  | $2 |  |  | $— |  |  | $3 |  |  | $3 |  |  | $— |  |  | $— |
Equity securities - U.S. | 4 |  |  | 4 |  |  | — |  |  | — |  |  | 4 |  |  | 4 |  |  | — |  |  | — |
Equity securities - international | 3 |  |  | 3 |  |  | — |  |  | — |  |  | 3 |  |  | 3 |  |  | — |  |  | — |
Fixed income securities | 72 |  |  | 71 |  |  | 1 |  |  | — |  |  | 69 |  |  | 68 |  |  | 1 |  |  | — |
Total assets in fair value hierarchy | 81 |  |  | $78 |  |  | $3 |  |  | $— |  |  | 79 |  |  | $78 |  |  | $1 |  |  | $— |
Assets measured at net asset value | 27 |  |  |  |  |  |  |  |  | 26 |  |  |  |  |  |  |
Total OPEB plan assets | $108 |  |  |  |  |  |  |  |  | $105 |  |  |  |  |  |  |

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| 2020 |  | 2019
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
IPL | Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Cash and equivalents | $1 |  |  | $— |  |  | $1 |  |  | $— |  |  | $2 |  |  | $2 |  |  | $— |  |  | $— |
Fixed income securities | 51 |  |  | 51 |  |  | — |  |  | — |  |  | 48 |  |  | 48 |  |  | — |  |  | — |
Total assets in fair value hierarchy | 52 |  |  | $51 |  |  | $1 |  |  | $— |  |  | 50 |  |  | $50 |  |  | $— |  |  | $— |
Assets measured at net asset value | 22 |  |  |  |  |  |  |  |  | 22 |  |  |  |  |  |  |
Total OPEB plan assets | $74 |  |  |  |  |  |  |  |  | $72 |  |  |  |  |  |  |

| 2020 |  | 2019
| Fair |  | Level |  | Level |  | Level |  | Fair |  | Level |  | Level |  | Level
WPL | Value |  | 1 |  | 2 |  | 3 |  | Value |  | 1 |  | 2 |  | 3
Fixed income securities | $18 |  |  | $18 |  |  | $— |  |  | $— |  |  | $17 |  |  | $17 |  |  | $— |  |  | $— |
Total OPEB plan assets | $18 |  |  | $18 |  |  | $— |  |  | $— |  |  | $17 |  |  | $17 |  |  | $— |  |  | $— |

For the various defined benefit pension and OPEB plans, Alliant Energy common stock represented less than 1% of assets directly held in the plans at December 31, 2020 and 2019.
401(k) Savings Plans - A significant number of employees participate in defined contribution retirement plans (401(k) savings plans). Alliant Energy common stock directly held by participants represented 9% and 11% of total assets in the 401(k) savings plans at December 31, 2020 and 2019, respectively. Costs related to the 401(k) savings plans, which are partially based on the participants’ contributions and include allocated costs associated with Corporate Services employees for IPL and WPL, were as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
401(k) costs | $25 |  |  | $25 |  |  | $25 |  |  | $13 |  |  | $13 |  |  | $13 |  |  | $12 |  |  | $12 |  |  | $11 |

NOTE 13(b) Equity-based Compensation Plans - In 2020, Alliant Energy’s shareowners approved the 2020 OIP, which permits the grant of shares of Alliant Energy common stock, restricted stock, restricted stock units, performance shares, performance units, and other stock-based or cash-based awards to key employees. The 2020 OIP replaced the Amended and Restated 2010 OIP, which permitted similar grants. At December 31, 2020, performance shares and restricted stock units (performance- and time-vesting) were outstanding under the 2020 OIP and the Amended and Restated 2010 OIP, and 9 million shares of Alliant Energy common stock remained available for grants under the 2020 OIP. Alliant Energy satisfies share payouts related to equity awards through the issuance of new shares of its common stock. Alliant Energy also has the DLIP, which permits the grant of cash-based long-term awards, including performance units, restricted cash awards and restricted units, to certain key employees. At December 31, 2020, performance units and restricted units (performance- and time-vesting) were outstanding under the DLIP, and the amount of nonvested restricted units was not material. There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash payments. Nonvested awards generally do not have non-forfeitable rights to dividends or dividend equivalents when dividends are paid to common shareowners. A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards was as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Compensation expense | $16 |  |  | $26 |  |  | $17 |  |  | $9 |  |  | $15 |  |  | $9 |  |  | $6 |  |  | $10 |  |  | $7 |
Income tax benefits | 4 |  |  | 7 |  |  | 5 |  |  | 2 |  |  | 4 |  |  | 3 |  |  | 2 |  |  | 3 |  |  | 2 |

As of December 31, 2020, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $5 million, $3 million and $2 million, respectively, which is expected to be recognized over a weighted average period of between one year and two years. Share-based compensation expense is recognized on a straight-line basis over the requisite service periods and is recorded in “Other operation and maintenance” in the income statements. As of December 31, 2020, 537,485 shares were included in the calculation of diluted EPS related to the nonvested equity awards.
Performance Shares - Equity Awards - Payouts of 2020 and 2019 performance shares are contingent upon achievement over a three-year period of specified performance criteria, which currently is total shareowner return relative to an investor-owned utility peer group. Performance shares granted in 2020 and 2019 are to be paid out in shares of Alliant Energy common stock and are accounted for as equity awards. The fair value of each performance share granted in 2020 and 2019 is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market condition contained in the agreement during a three-year performance period. The actual number of 2020 and 2019 performance shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of shares. If minimum performance targets are not met during the performance period, these performance

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shares are forfeited. Compensation expense is recorded ratably over the performance period based on the fair value of the awards at the grant date. A summary of the 2020 and 2019 performance shares activity, with amounts representing the target number of awards, was as follows:

| 2020 |  | 2019
| Performance Shares - Equity |  | Weighted Average Grant Date Fair Value |  | Performance Shares - Equity |  | Weighted Average Grant Date Fair Value
Nonvested awards, January 1 | 74,193 |  |  | $47.44 |  | — |  |  | $—
Granted | 56,204 |  |  | 64.04 |  | 91,816 |  |  | 47.23
Forfeited | (1,241) |  |  | 50.94 |  | (17,623) |  |  | 46.35
Nonvested awards, December 31 | 129,156 |  |  | 54.63 |  | 74,193 |  |  | 47.44

Performance Shares and Performance Units - Liability Awards - Payouts of performance shares granted prior to 2019 under the Amended and Restated 2010 OIP and performance units under the DLIP to key employees are contingent upon achievement over three-year periods of specified performance criteria, which currently is total shareowner return relative to an investor-owned utility peer group. Performance shares granted prior to 2019 can be paid out in shares of Alliant Energy common stock, cash or a combination of cash and stock. Performance units must be paid out in cash. Alliant Energy assumes it will make future payouts of its performance shares granted prior to 2019 and performance units in cash; therefore, these performance shares and performance units are accounted for as liability awards. Compensation expense for these performance shares and performance units is recorded ratably over the performance period based on the fair value of the awards at each reporting period. A summary of these performance shares and performance units activity, with amounts representing the target number of awards, was as follows:

| Performance Shares (granted prior to 2019) |  | Performance Units (granted prior to 2019)
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Nonvested awards, January 1 | 131,872 |  |  | 203,188 |  |  | 223,511 |  |  | 34,574 |  |  | 57,761 |  |  | 71,737 |
Granted | — |  |  | — |  |  | 74,163 |  |  | — |  |  | — |  |  | 19,840 |
Vested | (63,565) |  |  | (66,322) |  |  | (90,806) |  |  | (16,661) |  |  | (20,131) |  |  | (31,910) |
Forfeited | — |  |  | (4,994) |  |  | (3,680) |  |  | (1,112) |  |  | (3,056) |  |  | (1,906) |
Nonvested awards, December 31 | 68,307 |  |  | 131,872 |  |  | 203,188 |  |  | 16,801 |  |  | 34,574 |  |  | 57,761 |

Fair Value of Awards - The fair value of each performance share and performance unit accounted for as a liability award is based on the closing market price of one share of Alliant Energy common stock at the end of the performance period. The actual payout for performance shares and performance units is dependent upon actual performance and may range from zero to 200% of the target number of awards. At December 31, 2020, the Alliant Energy common stock closing price was $51.53, and additional information related to the fair value of nonvested performance shares and performance units granted in 2018 was as follows:

| Performance Shares |  | Performance Units
Nonvested awards at target | 68,307 |  | 16,801
Estimated payout percentage based on performance criteria | 172.5% |  | 172.5%
Fair values of each nonvested award | $88.89 |  | $88.89

Vested Awards - Certain performance shares and performance units vested, resulting in payouts (a combination of cash and common stock for the performance shares and cash only for the performance units) as follows:

| Performance Shares (granted prior to 2019) |  | Performance Units (granted prior to 2019)
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
| 2017 Grant |  | 2016 Grant |  | 2015 Grant |  | 2017 Grant |  | 2016 Grant |  | 2015 Grant
Performance awards vested | 63,565 |  | 66,322 |  | 90,806 |  | 16,661 |  | 20,131 |  | 31,910
Percentage of target number of performance awards | 155.0% |  | 142.5% |  | 137.5% |  | 155.0% |  | 142.5% |  | 137.5%
Aggregate payout value (in millions) | $6 |  | $4 |  | $5 |  | $2 |  | $1 |  | $1
Payout - cash (in millions) | $5 |  | $4 |  | $5 |  | $2 |  | $1 |  | $1
Payout - common stock shares issued | 9,543 |  | 6,447 |  | 5,078 |  | N/A |  | N/A |  | N/A

Restricted Stock Units - Equity Awards - Payouts of 2020 and 2019 restricted stock units are based on the expiration of a three-year time-vesting period. Restricted stock units granted in 2020 and 2019 are to be paid out in shares of Alliant Energy common stock and are accounted for as equity awards. The fair value of each restricted stock unit granted in 2020 and 2019 is based on the closing market price of one share of Alliant Energy common stock on the grant date of the award. Compensation expense is recorded ratably over the performance period based on the fair value of the awards on the grant date. A summary of the 2020 and 2019 restricted stock units activity was as follows:

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|  | 2020 |  | 2019
|  | Restricted Stock Units - Equity |  | Weighted Average Grant Date Fair Value |  | Restricted Stock Units - Equity |  | Weighted Average Grant Date Fair Value
Nonvested units, January 1 |  | 89,281 |  |  | $46.04 |  | — |  |  | $—
Granted |  | 61,056 |  |  | 59.42 |  | 105,348 |  |  | 45.98
Forfeited |  | (3,788) |  |  | 49.01 |  | (16,067) |  |  | 45.63
Nonvested units, December 31 |  | 146,549 |  |  | 51.54 |  | 89,281 |  |  | 46.04

Restricted Stock Units - Liability Awards - Payouts of restricted stock units granted prior to 2019 are based on the expiration of a three-year time-vesting period and can be paid out in shares of Alliant Energy common stock, cash or a combination of cash and stock. Alliant Energy assumes it will make future payouts of its restricted stock units granted prior to 2019 in cash; therefore, restricted stock units granted prior to 2019 are accounted for as liability awards. The fair value of each restricted stock unit granted prior to 2019 is based on the closing market price of one share of Alliant Energy common stock at the end of the time-vesting period. Compensation expense is recorded ratably over the performance period based on the fair value of the awards at each reporting period. A summary of the restricted stock units granted prior to 2019 activity was as follows:

| 2020 |  | 2019 |  | 2018
Nonvested units, January 1 | 113,033 |  |  | 174,163 |  |  | 113,749 |
Granted | — |  |  | — |  |  | 63,568 |
Vested | (54,483) |  |  | (56,849) |  |  | — |
Forfeited | — |  |  | (4,281) |  |  | (3,154) |
Nonvested units, December 31 | 58,550 |  |  | 113,033 |  |  | 174,163 |

Performance Restricted Stock Units - Equity Awards - Payouts of performance restricted stock units are based upon achievement of certain performance targets during a three-year performance period, which currently includes specified growth of consolidated net income from continuing operations. The actual number of units that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200% of the target number of units. If minimum performance targets are not met during the performance period, these units are forfeited. Performance restricted stock units generally must be paid out in shares and are accounted for as equity awards. The fair value of each performance restricted stock unit is based on the closing market price of one share of Alliant Energy common stock on the grant date of the award. Compensation expense is recorded ratably over the performance period based on a probability assessment of payouts for the awards at each reporting period. A summary of the performance restricted stock units activity, with amounts representing the target number of units, was as follows:

| 2020 |  | 2019 |  | 2018
| Units |  | Weighted Average Grant Date Fair Value |  | Units |  | Weighted Average Grant Date Fair Value |  | Units |  | Weighted Average Grant Date Fair Value
Nonvested units, January 1 | 206,065 |  |  | $41.50 |  | 203,188 |  |  | $37.23 |  | 132,705 |  |  | $36.50
Granted | 56,204 |  |  | 59.37 |  | 91,816 |  |  | 46.10 |  | 74,163 |  |  | 38.60
Vested | (63,565) |  |  | 39.12 |  | (66,322) |  |  | 33.93 |  | — |  |  | —
Forfeited | (1,241) |  |  | 49.25 |  | (22,617) |  |  | 44.00 |  | (3,680) |  |  | 38.60
Nonvested units, December 31 | 197,463 |  |  | 47.31 |  | 206,065 |  |  | 41.50 |  | 203,188 |  |  | 37.23

NOTE 13(c) Deferred Compensation Plan - Alliant Energy maintains a DCP under which key employees may defer up to 100% of base salary and short-term cash incentive compensation and directors may elect to defer all or part of their retainer and committee fees. Key employees who have made the maximum allowed contribution to the Alliant Energy 401(k) Savings Plan may receive an additional credit to the DCP. Key employees and directors may elect to have their deferrals credited to a company stock account, an interest account, equity accounts or mutual fund accounts based on certain benchmark funds.
Company Stock Account - The DCP does not permit diversification of deferrals credited to the company stock account and all distributions from participants’ company stock accounts are made in the form of shares of Alliant Energy common stock. The deferred compensation obligations for participants’ company stock accounts are recorded in “Additional paid-in capital” and the shares of Alliant Energy common stock held in a rabbi trust to satisfy this obligation are recorded in “Shares in deferred compensation trust” on Alliant Energy’s balance sheets. At December 31, the carrying value of the deferred compensation obligation for the company stock account and the shares in the deferred compensation trust based on the historical value of the shares of Alliant Energy common stock contributed to the rabbi trust, and the fair market value of the shares held in the rabbi trust, were as follows (in millions):

| 2020 |  | 2019
Carrying value | $11 |  |  | $10 |
Fair market value | 20 |  |  | 21 |

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Interest, Equity and Mutual Fund Accounts - Distributions from participants’ interest, equity and mutual fund accounts are in the form of cash payments. The deferred compensation obligations for participants’ interest, equity and mutual fund accounts are recorded in “Pension and other benefit obligations” on the balance sheets. At December 31, 2020 and 2019, the carrying value of Alliant Energy’s deferred compensation obligations for participants’ interest, equity and mutual fund accounts, which approximates fair market value, was $22 million and $21 million, respectively.
NOTE 14. ASSET RETIREMENT OBLIGATIONS
Recognized AROs relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind farms, ash ponds, active ash landfills, above ground storage tanks, coal yards and solar generation. Recognized AROs also include legal obligations for the management and final disposition of asbestos and polychlorinated biphenyls. AROs are recorded in “Other current liabilities” and “Other liabilities” on the balance sheets. Refer to Note 2 for information regarding regulatory assets related to AROs. A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Balance, January 1 | $196 |  |  | $177 |  |  | $134 |  |  | $118 |  |  | $62 |  |  | $59 |
Revisions in estimated cash flows | 13 |  |  | (6) |  |  | 9 |  |  | (7) |  |  | 4 |  |  | 1 |
Liabilities settled | (13) |  |  | (8) |  |  | (9) |  |  | (8) |  |  | (4) |  |  | — |
Liabilities incurred (a) | 48 |  |  | 26 |  |  | 38 |  |  | 26 |  |  | 10 |  |  | — |
Accretion expense | 7 |  |  | 7 |  |  | 5 |  |  | 5 |  |  | 2 |  |  | 2 |
Balance, December 31 | $251 |  |  | $196 |  |  | $177 |  |  | $134 |  |  | $74 |  |  | $62 |

(a)In 2020, IPL placed in service the Whispering Willow North, Golden Plains and Richland wind sites, and WPL placed in service the Kossuth wind site. As a result, Alliant Energy, IPL and WPL recognized additional AROs in 2020, which resulted in corresponding increases in property, plant and equipment, net on the respective balance sheets.
NOTE 15. DERIVATIVE INSTRUMENTS
Commodity Derivatives -
Purpose - Derivative instruments are used for risk management purposes to mitigate exposures to fluctuations in certain commodity prices, transmission congestion costs and rail transportation costs. Risk policies are maintained that govern the use of such derivative instruments. Derivative instruments were not designated as hedging instruments and included the following:

Risk management purpose | Type of instrument
Mitigate pricing volatility for: |
Fuel used to supply natural gas-fired EGUs | Natural gas swap, options and physical forward contracts (IPL and WPL)
Natural gas supplied to retail customers | Natural gas swap, options and physical forward contracts (IPL and WPL)
Fuel used at coal-fired EGUs | Coal physical forward contracts (IPL and WPL)
Optimize the value of natural gas pipeline capacity | Natural gas physical forward contracts (IPL and WPL)
| Natural gas swap contracts (IPL)
Manage transmission congestion costs | FTRs (IPL and WPL)
Manage rail transportation costs | Diesel fuel swap contracts (WPL)

Notional Amounts - As of December 31, 2020, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

|  |  | FTRs |  | Natural Gas |  | Coal |  | Diesel Fuel
|  |  |  |  | MWhs |  | Years |  | Dths |  | Years |  | Tons |  | Years |  | Gallons |  | Years
Alliant Energy |  |  |  |  | 9,285 |  |  | 2021 |  | 208,542 |  |  | 2021-2028 |  | 5,648 |  |  | 2021-2023 |  | 5,544 |  |  | 2021-2022
IPL |  |  |  |  | 3,398 |  |  | 2021 |  | 109,063 |  |  | 2021-2028 |  | 2,548 |  |  | 2021-2023 |  | — |  |  | —
WPL |  |  |  |  | 5,887 |  |  | 2021 |  | 99,479 |  |  | 2021-2027 |  | 3,100 |  |  | 2021-2023 |  | 5,544 |  |  | 2021-2022

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Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheet as assets or liabilities. At December 31, the fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019 |  | 2020 |  | 2019
Current derivative assets | $24 |  | $16 |  | $20 |  | $12 |  | $4 |  | $4
Non-current derivative assets | 10 |  | 11 |  | 9 |  | 10 |  | 1 |  | 1
Current derivative liabilities | 9 |  | 19 |  | 3 |  | 9 |  | 6 |  | 10
Non-current derivative liabilities | 16 |  | 19 |  | 9 |  | 9 |  | 7 |  | 10

Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided in the form of letters of credit or cash collateral up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At December 31, 2020 and 2019, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered.
Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, amounts would not be materially different from gross amounts of derivative assets and derivative liabilities at December 31, 2020 and 2019. Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.
NOTE 16. FAIR VALUE MEASUREMENTS
Valuation Hierarchy - Fair value measurement accounting establishes three levels of fair value hierarchy that prioritize the inputs to valuation techniques used to measure fair value. Level 1 pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. Level 2 pricing inputs are quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active as of the reporting date. Level 3 pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation.
The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability.
Valuation Techniques -
Derivative assets and derivative liabilities - Swap, option and physical forward commodity contracts were non-exchange-based derivative instruments and were valued using indicative price quotations from a pricing vendor that provides daily exchange forward price settlements, from broker or dealer quotations, from market publications or from on-line exchanges. The indicative price quotations reflected the average of the bid-ask mid-point prices and were obtained from sources believed to provide the most liquid market for the commodity. A portion of these indicative price quotations were corroborated using quoted prices for similar assets or liabilities in active markets and categorized derivative instruments based on such indicative price quotations as Level 2. Commodity contracts that were valued using indicative price quotations based on significant assumptions such as seasonal or monthly shaping and indicative price quotations that could not be readily corroborated were categorized as Level 3. Swap, option and physical forward commodity contracts were predominately at liquid trading points. FTRs were valued using auction prices and were categorized as Level 3. Refer to Note 15 for additional details of derivative assets and derivative liabilities.
Deferred proceeds (sales of receivables) - The fair value of IPL’s deferred proceeds related to its sales of accounts receivable program was calculated each reporting date using the cost approach valuation technique. The fair value represents the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold due to the short-term nature of the collection period. These inputs were considered unobservable and deferred proceeds were categorized as Level 3. Deferred proceeds represent IPL’s maximum exposure to loss related to the receivables sold. Refer to Note 5(b) for additional information regarding deferred proceeds.

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Long-term debt (including current maturities) - The fair value of long-term debt instruments was based on a discounted cash flow methodology using observable data from comparably traded securities with similar credit profiles, and was substantially classified as Level 2. Refer to Note 9(b) for additional information regarding long-term debt.
Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and the related estimated fair values of other financial instruments at December 31 were as follows (in millions):

Alliant Energy | 2020 |  | 2019
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $44 |  |  | $44 |  |  | $— |  |  | $— |  |  | $44 |  |  | $5 |  |  | $5 |  |  | $— |  |  | $— |  |  | $5 |
Derivatives | 34 |  |  | — |  |  | 5 |  |  | 29 |  |  | 34 |  |  | 27 |  |  | — |  |  | 5 |  |  | 22 |  |  | 27 |
Deferred proceeds | 188 |  |  | — |  |  | — |  |  | 188 |  |  | 188 |  |  | 188 |  |  | — |  |  | — |  |  | 188 |  |  | 188 |
Liabilities and equity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives | 25 |  |  | — |  |  | 25 |  |  | — |  |  | 25 |  |  | 38 |  |  | — |  |  | 37 |  |  | 1 |  |  | 38 |
Long-term debt (incl. current maturities) | 6,777 |  |  | — |  |  | 8,107 |  |  | 2 |  |  | 8,109 |  |  | 6,190 |  |  | — |  |  | 6,918 |  |  | 2 |  |  | 6,920 |

IPL | 2020 |  | 2019
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market fund investments | $44 |  |  | $44 |  |  | $— |  |  | $— |  |  | $44 |  |  | $5 |  |  | $5 |  |  | $— |  |  | $— |  |  | $5 |
Derivatives | 29 |  |  | — |  |  | 3 |  |  | 26 |  |  | 29 |  |  | 22 |  |  | — |  |  | 3 |  |  | 19 |  |  | 22 |
Deferred proceeds | 188 |  |  | — |  |  | — |  |  | 188 |  |  | 188 |  |  | 188 |  |  | — |  |  | — |  |  | 188 |  |  | 188 |
Liabilities and equity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives | 12 |  |  | — |  |  | 12 |  |  | — |  |  | 12 |  |  | 18 |  |  | — |  |  | 17 |  |  | 1 |  |  | 18 |
Long-term debt (incl. current maturities) | 3,345 |  |  | — |  |  | 4,021 |  |  | — |  |  | 4,021 |  |  | 3,147 |  |  | — |  |  | 3,489 |  |  | — |  |  | 3,489 |

WPL | 2020 |  | 2019
|  |  | Fair Value |  |  |  | Fair Value
| Carrying |  | Level |  | Level |  | Level |  |  |  | Carrying |  | Level |  | Level |  | Level |  |
| Amount |  | 1 |  | 2 |  | 3 |  | Total |  | Amount |  | 1 |  | 2 |  | 3 |  | Total
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives | $5 |  |  | $— |  |  | $2 |  |  | $3 |  |  | $5 |  |  | $5 |  |  | $— |  |  | $2 |  |  | $3 |  |  | $5 |
Liabilities and equity: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivatives | 13 |  |  | — |  |  | 13 |  |  | — |  |  | 13 |  |  | 20 |  |  | — |  |  | 20 |  |  | — |  |  | 20 |
Long-term debt (incl. current maturities) | 2,130 |  |  | — |  |  | 2,690 |  |  | — |  |  | 2,690 |  |  | 1,933 |  |  | — |  |  | 2,268 |  |  | — |  |  | 2,268 |

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Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
| 2020 |  | 2019 |  | 2020 |  | 2019
Beginning balance, January 1 | $21 |  |  | $12 |  |  | $188 |  |  | $119 |
Total net gains included in changes in net assets (realized/unrealized) | 11 |  |  | 8 |  |  | — |  |  | — |
Transfers out of Level 3 (a) | — |  |  | 4 |  |  | — |  |  | — |
Purchases | 14 |  |  | 14 |  |  | — |  |  | — |
Sales | (1) |  |  | — |  |  | — |  |  | — |
Settlements (b) | (16) |  |  | (17) |  |  | — |  |  | 69 |
Ending balance, December 31 | $29 |  |  | $21 |  |  | $188 |  |  | $188 |
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at December 31 | $11 |  |  | $11 |  |  | $— |  |  | $— |

IPL | Commodity Contract Derivative |  |
| Assets and (Liabilities), net |  | Deferred Proceeds
| 2020 |  | 2019 |  | 2020 |  | 2019
Beginning balance, January 1 | $18 |  |  | $9 |  |  | $188 |  |  | $119 |
Total net gains included in changes in net assets (realized/unrealized) | 10 |  |  | 11 |  |  | — |  |  | — |
Transfers out of Level 3 (a) | — |  |  | 2 |  |  | — |  |  | — |
Purchases | 11 |  |  | 9 |  |  | — |  |  | — |
Sales | (1) |  |  | — |  |  | — |  |  | — |
Settlements (b) | (12) |  |  | (13) |  |  | — |  |  | 69 |
Ending balance, December 31 | $26 |  |  | $18 |  |  | $188 |  |  | $188 |
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at December 31 | $10 |  |  | $12 |  |  | $— |  |  | $— |

(a)Observable market inputs became available for certain commodity contracts previously classified as Level 3 for transfers out of Level 3.
(b)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.
Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets at December 31 as follows (in millions):

| Alliant Energy |  | IPL |  | WPL
| Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs |  | Excluding FTRs |  | FTRs
2020 | $18 |  |  | $11 |  |  | $17 |  |  | $9 |  |  | $1 |  |  | $2 |
2019 | 15 |  |  | 7 |  |  | 14 |  |  | 5 |  |  | 1 |  |  | 2 |

NOTE 17. COMMITMENTS AND CONTINGENCIES
NOTE 17(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including WPL’s expansion of solar generation. At December 31, 2020, Alliant Energy’s and WPL’s minimum future commitments in 2021 for these projects were $8 million and $7 million, respectively.
NOTE 17(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At December 31, 2020, the related minimum future commitments were as follows (in millions):

Alliant Energy | 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025 |  | Thereafter |  | Total
Natural gas | 252 |  | 174 |  | 137 |  | 105 |  | 68 |  | 185 |  | 921
Coal | 70 |  | 27 |  | 17 |  | — |  | — |  | — |  | 114
Other (a) | 61 |  | 17 |  | 11 |  | 8 |  | 3 |  | 29 |  | 129
| $383 |  | $218 |  | $165 |  | $113 |  | $71 |  | $214 |  | $1,164

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IPL | 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025 |  | Thereafter |  | Total
Natural gas | 130 |  | 88 |  | 79 |  | 68 |  | 38 |  | 71 |  | 474
Coal | 32 |  | 16 |  | 13 |  | — |  | — |  | — |  | 61
Other (a) | 25 |  | 5 |  | 4 |  | 2 |  | 2 |  | 27 |  | 65
| $187 |  | $109 |  | $96 |  | $70 |  | $40 |  | $98 |  | $600

WPL | 2021 |  | 2022 |  | 2023 |  | 2024 |  | 2025 |  | Thereafter |  | Total
Natural gas | 122 |  | 86 |  | 58 |  | 37 |  | 30 |  | 114 |  | 447
Coal | 38 |  | 11 |  | 4 |  | — |  | — |  | — |  | 53
Other (a) | 26 |  | 2 |  | 1 |  | 1 |  | 1 |  | 1 |  | 32
| $186 |  | $99 |  | $63 |  | $38 |  | $31 |  | $115 |  | $532

(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2020.
NOTE 17(c) Legal Proceedings - Alliant Energy, IPL and WPL are involved in legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that appropriate reserves have been established and final disposition of these actions will not have a material effect on their financial condition or results of operations.
NOTE 17(d) Guarantees and Indemnifications -
Whiting Petroleum - Whiting Petroleum is an independent oil and gas company. In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6% share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations.
As of December 31, 2020, the currently known partnership obligations for the abandonment obligations are estimated at $68 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy estimates its expected loss to be a portion of the $68 million of known partnership abandonment obligations of the Whiting Petroleum affiliate and the other partners. Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay; however, the new credit loss accounting standard adopted on January 1, 2020 requires recognition of a liability for expected credit losses related to the contingent obligations that are in the scope of these guarantees. With the adoption of this standard, Alliant Energy recorded a pre-tax $12 million cumulative effect adjustment to decrease the opening balance of retained earnings as of January 1, 2020.
In April 2020, Whiting Petroleum filed for bankruptcy, and in September 2020, Whiting Petroleum completed its reorganization and emerged from bankruptcy. As a result of Whiting Petroleum’s completed bankruptcy proceedings, as well as additional information regarding the guarantees obtained from the bankruptcy proceedings, the credit loss liability was decreased to $5 million in 2020. The credit loss liability is recorded in “Other liabilities” on Alliant Energy’s balance sheet as of December 31, 2020. In 2020, the pre-tax credit loss adjustment of $7 million was recorded as a reduction in Alliant Energy’s “Other operation and maintenance” expenses.
Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third-party under a long-term PPA. Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $74 million as of December 31, 2020 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of December 31, 2020 and 2019.
NOTE 17(e) Environmental Matters - Alliant Energy, IPL and WPL are subject to environmental regulations as a result of their current and past operations. These regulations are designed to protect public health and the environment and have resulted in compliance, remediation, containment and monitoring obligations, which are recorded as current and non-current environmental liabilities. Substantially all of the environmental liabilities recorded on the balance sheets relate to MGP sites.
MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring

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costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At December 31, 2020, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions). At December 31, 2020, such amounts for WPL were not material.

| Alliant Energy |  | IPL
Range of estimated future costs | $11 |  | - | $28 |  | $8 |  | - | $22
Current and non-current environmental liabilities | 15 |  | 12

IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential CAA issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Burlington by December 31, 2021 and Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers.
Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Effluent Limitation Guidelines, CCR Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the CAA.
NOTE 17(f) Credit Risk - IPL provides retail electric and gas services in Iowa and wholesale electric service in Minnesota, Illinois and Iowa. WPL provides retail electric and gas services and wholesale electric service in Wisconsin. The geographic concentration of IPL’s and WPL’s customers did not contribute significantly to overall credit risk exposure. In addition, as a result of a diverse customer base, IPL and WPL did not have any significant credit risk concentration for receivables arising from the sale of electricity or gas services.
Alliant Energy, IPL and WPL are subject to credit risk related to the ability of counterparties to meet their contractual payment obligations or the potential non-performance of counterparties to deliver contracted commodities and other goods or services at the contracted price. Credit policies are maintained to mitigate credit risk. These credit policies include evaluation of the financial condition of certain counterparties, use of credit risk-related contingent provisions in certain agreements that require credit support from counterparties not meeting specific criteria, diversification of counterparties to reduce concentrations of credit risk and the use of standardized agreements that facilitate the netting of cash flows associated with certain counterparties. Based on these credit policies and counterparty diversification, as well as utility cost recovery mechanisms, it is unlikely that counterparty non-performance would have a material effect on financial condition or results of operations. However, there is no assurance that these items will protect against all losses from counterparty non-performance.
Refer to Notes 5(a) and 15 for details of allowances for expected credit losses and credit risk-related contingent features, respectively.
NOTE 17(g) MISO Transmission Owner Return on Equity Complaints - A group of MISO cooperative and municipal utilities previously filed complaints with FERC requesting a reduction to the base return on equity used by MISO transmission owners, including ITC and ATC. The first complaint covered the period from November 12, 2013 through February 11, 2015. In 2017, IPL and WPL received refunds related to the first complaint period, which were subsequently refunded to their retail and wholesale customers. The second complaint covered the period from February 12, 2015 through May 11, 2016. In November 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity used by the MISO transmission owners to 9.88% effective for the first complaint period and subsequent to September 28, 2016. The November 2019 FERC order also dismissed the second complaint; therefore, FERC did not direct refunds to be made for that complaint. In May 2020, FERC issued an order in response to various rehearing requests and increased the base return on equity used by the MISO transmission owners from 9.88% to 10.02% for the first complaint period and subsequent to September 28, 2016, which reduces the refunds originally anticipated to be received by IPL and WPL as a result of FERC’s November 2019 order.
In 2020, IPL and WPL received $15 million and $5 million, respectively, in refunds related to the FERC orders. In October 2020, FERC extended the time to complete additional refunds to September 2021. IPL currently expects that all refunds will be returned to its retail electric customers after refund amounts and timing are known and a refund plan is approved by the IUB. IPL currently expects that a portion of the refunds will be returned to its retail electric customers in 2021. Pursuant to PSCW authorization, WPL will retain the refunds to maintain its current retail electric base rates through the end of 2021. WPL currently expects that any refunds not utilized to maintain base rates would be returned to its customers in WPL’s next retail

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electric rate review proceeding. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.
NOTE 18. SEGMENTS OF BUSINESS
Alliant Energy - Alliant Energy’s principal businesses as of December 31, 2020 are:
•Utility - includes the operations of IPL and WPL, which primarily serve retail customers in Iowa and Wisconsin. The utility business has three reportable segments: a) utility electric operations; b) utility gas operations; and c) utility other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total Utility.”
•ATC Holdings, Non-utility, Parent and Other - includes the operations of AEF and its subsidiaries, Corporate Services, the Alliant Energy parent company, and any Alliant Energy parent company consolidating adjustments. AEF is comprised of Alliant Energy’s interest in ATC Holdings, Travero, a non-utility wind farm, the Sheboygan Falls Energy Facility and other non-utility holdings.
Alliant Energy’s administrative support services are directly charged to the applicable segment where practicable. In all other cases, administrative support services are allocated to the applicable segment based on services agreements. Intersegment revenues were not material to Alliant Energy’s operations and there was no single customer whose revenues were 10% or more of Alliant Energy’s consolidated revenues. All of Alliant Energy’s operations and assets are located in the U.S. Certain financial information relating to Alliant Energy’s business segments, which represent the services provided to its customers, was as follows (in millions):

|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2020 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $2,920 |  |  | $373 |  |  | $49 |  |  | $3,342 |  |  | $74 |  | $3,416
Depreciation and amortization | 556 |  |  | 49 |  |  | 5 |  |  | 610 |  |  | 5 |  | 615
Operating income (loss) | 643 |  |  | 74 |  |  | (1) |  |  | 716 |  |  | 24 |  | 740
Interest expense |  |  |  |  |  |  | 243 |  |  | 32 |  | 275
Equity income from unconsolidated investments, net | (2) |  |  | — |  |  | — |  |  | (2) |  |  | (59) |  | (61)
Income tax expense (benefit) |  |  |  |  |  |  | (66) |  |  | 9 |  | (57)
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 573 |  |  | 41 |  | 614
Total assets | 14,358 |  |  | 1,413 |  |  | 990 |  |  | 16,761 |  |  | 949 |  | 17,710
Investments in equity method subsidiaries | 11 |  |  | — |  |  | — |  |  | 11 |  |  | 465 |  | 476
Construction and acquisition expenditures | 1,109 |  |  | 182 |  |  | 2 |  |  | 1,293 |  |  | 73 |  | 1,366

|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2019 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,064 |  |  | $455 |  |  | $46 |  |  | $3,565 |  |  | $83 |  | $3,648
Depreciation and amortization | 513 |  |  | 47 |  |  | 3 |  |  | 563 |  |  | 4 |  | 567
Operating income | 679 |  |  | 70 |  |  | 1 |  |  | 750 |  |  | 28 |  | 778
Interest expense |  |  |  |  |  |  | 229 |  |  | 44 |  | 273
Equity income from unconsolidated investments, net | (1) |  |  | — |  |  | — |  |  | (1) |  |  | (52) |  | (53)
Income tax expense (benefit) |  |  |  |  |  |  | 73 |  |  | (4) |  | 69
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 517 |  |  | 40 |  | 557
Total assets | 13,659 |  |  | 1,269 |  |  | 856 |  |  | 15,784 |  |  | 917 |  | 16,701
Investments in equity method subsidiaries | 9 |  |  | — |  |  | — |  |  | 9 |  |  | 449 |  | 458
Construction and acquisition expenditures | 1,439 |  |  | 100 |  |  | — |  |  | 1,539 |  |  | 101 |  | 1,640

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|  |  |  |  |  |  |  |  | ATC Holdings, |  |
| Utility |  | Non-utility, |  | Alliant Energy
2018 | Electric |  | Gas |  | Other |  | Total |  | Parent and Other |  | Consolidated
Revenues | $3,000 |  |  | $447 |  |  | $48 |  |  | $3,495 |  |  | $39 |  | $3,534
Depreciation and amortization | 457 |  |  | 42 |  |  | 3 |  |  | 502 |  |  | 5 |  | 507
Operating income | 610 |  |  | 53 |  |  | 1 |  |  | 664 |  |  | 30 |  | 694
Interest expense |  |  |  |  |  |  | 217 |  |  | 30 |  | 247
Equity income from unconsolidated investments, net | (1) |  |  | — |  |  | — |  |  | (1) |  |  | (54) |  | (55)
Income taxes |  |  |  |  |  |  | 33 |  |  | 15 |  | 48
Net income attributable to Alliant Energy common shareowners |  |  |  |  |  |  | 472 |  |  | 40 |  | 512
Total assets | 12,486 |  |  | 1,184 |  |  | 893 |  |  | 14,563 |  |  | 863 |  | 15,426
Investments in equity method subsidiaries | 8 |  |  | — |  |  | — |  |  | 8 |  |  | 413 |  | 421
Construction and acquisition expenditures | 1,422 |  |  | 147 |  |  | — |  |  | 1,569 |  |  | 65 |  | 1,634

IPL - IPL is a utility primarily serving retail customers in Iowa and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes steam operations and the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to IPL’s operations and there was no single customer whose revenues were 10% or more of IPL’s consolidated revenues. All of IPL’s operations and assets are located in the U.S. Certain financial information relating to IPL’s business segments, which represent the services provided to its customers, was as follows (in millions):

2020 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,695 |  | $208 |  | $44 |  | $1,947 |
Depreciation and amortization | 321 |  | 30 |  | 5 |  | 356 |
Operating income | 358 |  | 50 |  | 2 |  | 410 |
Interest expense |  |  |  |  |  |  | 139 |
Income tax benefit |  |  |  |  |  |  | (47) |
Net income available for common stock |  |  |  |  |  |  | 324 |
Total assets | 8,518 |  | 766 |  | 565 |  | 9,849 |
Construction and acquisition expenditures | 626 |  | 59 |  | 2 |  | 687 |

2019 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,781 |  | $264 |  | $44 |  | $2,089 |
Depreciation and amortization | 295 |  | 29 |  | 3 |  | 327 |
Operating income | 360 |  | 39 |  | 4 |  | 403 |
Interest expense |  |  |  |  |  |  | 127 |
Income taxes |  |  |  |  |  |  | 24 |
Net income available for common stock |  |  |  |  |  |  | 284 |
Total assets | 8,075 |  | 734 |  | 468 |  | 9,277 |
Construction and acquisition expenditures | 964 |  | 56 |  | — |  | 1,020 |

2018 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,731 |  | $266 |  | $45 |  | $2,042 |
Depreciation and amortization | 255 |  | 25 |  | 3 |  | 283 |
Operating income | 318 |  | 28 |  | 5 |  | 351 |
Interest expense |  |  |  |  |  |  | 119 |
Income tax benefit |  |  |  |  |  |  | (3) |
Net income available for common stock |  |  |  |  |  |  | 264 |
Total assets | 7,220 |  | 687 |  | 504 |  | 8,411 |
Construction and acquisition expenditures | 891 |  | 100 |  | — |  | 991 |

WPL - WPL is a utility serving customers in Wisconsin and includes three reportable segments: a) electric operations; b) gas operations; and c) other, which includes the unallocated portions of the utility business. Various line items in the following tables are not allocated to the electric and gas segments for management reporting purposes, and therefore, are included only in “Total.” Intersegment revenues were not material to WPL’s operations and there was no single customer whose revenues were 10% or more of WPL’s consolidated revenues. All of WPL’s operations and assets are located in the U.S. Certain financial information relating to WPL’s business segments, which represent the services provided to its customers, was as follows (in millions):

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2020 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,225 |  |  | $165 |  |  | $5 |  |  | $1,395 |
Depreciation and amortization | 235 |  |  | 19 |  |  | — |  |  | 254 |
Operating income (loss) | 285 |  |  | 24 |  |  | (3) |  |  | 306 |
Interest expense |  |  |  |  |  |  | 104 |
Income tax benefit |  |  |  |  |  |  | (19) |
Net income |  |  |  |  |  |  | 249 |
Total assets | 5,840 |  |  | 647 |  |  | 425 |  |  | 6,912 |
Construction and acquisition expenditures | 483 |  |  | 123 |  |  | — |  |  | 606 |

2019 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,283 |  |  | $191 |  |  | $2 |  |  | $1,476 |
Depreciation and amortization | 218 |  |  | 18 |  |  | — |  |  | 236 |
Operating income (loss) | 319 |  |  | 31 |  |  | (3) |  |  | 347 |
Interest expense |  |  |  |  |  |  | 102 |
Income taxes |  |  |  |  |  |  | 49 |
Net income |  |  |  |  |  |  | 233 |
Total assets | 5,584 |  |  | 535 |  |  | 388 |  |  | 6,507 |
Construction and acquisition expenditures | 475 |  |  | 44 |  |  | — |  |  | 519 |

2018 | Electric |  | Gas |  | Other |  | Total
Revenues | $1,269 |  |  | $181 |  |  | $3 |  |  | $1,453 |
Depreciation and amortization | 202 |  |  | 17 |  |  | — |  |  | 219 |
Operating income (loss) | 292 |  |  | 25 |  |  | (4) |  |  | 313 |
Interest expense |  |  |  |  |  |  | 98 |
Income taxes |  |  |  |  |  |  | 36 |
Net income |  |  |  |  |  |  | 208 |
Total assets | 5,266 |  |  | 497 |  |  | 389 |  |  | 6,152 |
Construction and acquisition expenditures | 531 |  |  | 47 |  |  | — |  |  | 578 |

NOTE 19. RELATED PARTIES
Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases were as follows (in millions):

| IPL |  | WPL
| 2020 |  | 2019 |  | 2018 |  | 2020 |  | 2019 |  | 2018
Corporate Services billings | $176 |  | $185 |  | $170 |  | $142 |  | $142 |  | $132
Sales credited | 35 |  | 68 |  | 48 |  | 3 |  | 7 |  | 28
Purchases billed | 329 |  | 331 |  | 358 |  | 108 |  | 120 |  | 81

As of December 31, net intercompany payables to Corporate Services were as follows (in millions):

| 2020 |  | 2019
IPL | $110 |  | $112
WPL | 73 |  | 85

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties were as follows (in millions):

| 2020 |  | 2019 |  | 2018
ATC billings to WPL | $108 |  | $109 |  | $106
WPL billings to ATC | 10 |  | 13 |  | 11

As of December 31, 2020 and 2019, WPL owed ATC net amounts of $9 million and $9 million, respectively.

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In 2020, WPL received $46 million from ATC related to construction deposits WPL previously provided ATC for transmission network upgrades for West Riverside, which is substantially recorded in “Other” in Alliant Energy’s and WPL’s cash flows from investing activities.
WPL’s Sheboygan Falls Energy Facility Lease - Refer to Note 10 for discussion of WPL’s Sheboygan Falls Energy Facility lease.
ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE
None.
ITEM 9A. CONTROLS AND PROCEDURES
Alliant Energy’s, IPL’s and WPL’s management evaluated, with the participation of each of Alliant Energy’s, IPL’s and WPL’s Chief Executive Officer, Chief Financial Officer and Disclosure Committee, the effectiveness of the design and operation of Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures as of the end of the quarter ended December 31, 2020 pursuant to the requirements of the Securities Exchange Act of 1934, as amended. Based on their evaluation, the Chief Executive Officer and the Chief Financial Officer concluded that Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures were effective as of the end of the quarter ended December 31, 2020.
There was no change in Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting that occurred during the quarter ended December 31, 2020 that has materially affected, or is reasonably likely to materially affect, Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting. Alliant Energy, IPL and WPL have not experienced any material impact to their internal control over financial reporting due to the COVID-19 pandemic, and continue to monitor and assess the impact COVID-19 has on their internal controls.
Management’s Annual Report on Internal Control over Financial Reporting - The management of Alliant Energy, IPL and WPL are responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934. Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with GAAP.
Because of the inherent limitations of internal control over financial reporting, misstatements may not be prevented or detected on a timely basis. Also, projections of any evaluation of the effectiveness of the internal control over financial reporting to future periods are subject to the risk that the controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.
Alliant Energy’s, IPL’s and WPL’s management assessed the effectiveness of their respective internal control over financial reporting as of December 31, 2020 using the criteria set forth in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on these assessments, Alliant Energy’s, IPL’s and WPL’s management concluded that, as of December 31, 2020, their respective internal control over financial reporting was effective.
Deloitte & Touche LLP, Alliant Energy’s independent registered public accounting firm, has audited Alliant Energy’s internal control over financial reporting. That report is included herein. This report does not include an attestation report of IPL’s and WPL’s independent registered public accounting firm regarding its assessment of IPL’s and WPL’s internal control over financial reporting.

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
To the Shareowners and the Board of Directors of Alliant Energy Corporation:
Opinion on Internal Control over Financial Reporting
We have audited the internal control over financial reporting of Alliant Energy Corporation and subsidiaries (the “Company”) as of December 31, 2020, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2020, based on criteria established in Internal Control - Integrated Framework (2013) issued by COSO.
We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2020, of the Company and our report dated February 19, 2021, expressed an unqualified opinion on those financial statements.
Basis for Opinion
The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Annual Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.
Definition and Limitations of Internal Control over Financial Reporting
A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.
Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.
/s/ DELOITTE & TOUCHE LLP
Milwaukee, Wisconsin
February 19, 2021

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ITEM 9B. OTHER INFORMATION
None.
PART III
ITEM 10. DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE
The directors of Alliant Energy, IPL and WPL are the same, and therefore, the information required by Item 10 relating to directors and nominees for election of directors is the same for all registrants. The information required by Item 10 relating to directors and nominees for election of directors at the 2021 Annual Meeting of Shareowners, the timely filing of reports under Section 16 of the Securities Exchange Act of 1934, audit committees and audit committee financial experts, and Alliant Energy’s, IPL’s and WPL’s Code of Conduct is incorporated herein by reference to the relevant information in the 2021 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s, IPL’s and WPL’s fiscal years. The code of ethics, also referred to as the Code of Conduct, of Alliant Energy, IPL and WPL are the same. Information regarding executive officers of Alliant Energy, IPL and WPL may be found in Part I of this report under the caption “Information About Executive Officers.”
ITEM 11. EXECUTIVE COMPENSATION
The directors and executive officers of Alliant Energy, IPL and WPL for which compensation information must be included are the same. Therefore, the information required by Item 11 for each of Alliant Energy, IPL and WPL is incorporated herein by reference to the relevant information in the 2021 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s, IPL’s and WPL’s fiscal years.
ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS
ALLIANT ENERGY
Information regarding Alliant Energy’s equity compensation plans as of December 31, 2020 was as follows:

|  | (A) |  |  |  | (C)
|  | Number of securities to be |  | (B) |  | Number of securities remaining available
|  | issued upon exercise of |  | Weighted-average exercise |  | for future issuance under equity
|  | outstanding options, |  | price of outstanding options, |  | compensation plans (excluding
Plan Category |  | warrants and rights |  | warrants and rights |  | securities reflected in column (A))
Equity compensation plans approved by shareowners |  | 4,376 (a) |  | $61.30 |  | 8,995,594 (b)
Equity compensation plans not approved by shareowners (c) |  | N/A |  | N/A |  | N/A (d)
|  | 4,376 |  | $61.30 |  | 8,995,594

(a)Represents performance shares, performance restricted stock units and restricted stock units granted under the 2020 OIP. Performance restricted stock units and performance shares are paid out in shares of Alliant Energy’s common stock. The performance share and performance restricted stock unit awards are adjusted by a performance multiplier, which ranges from zero to 200%, based on the performance criteria. The performance share and performance restricted stock unit awards included in column (A) of the table reflect an assumed payout in the form of Alliant Energy’s common stock at the maximum performance multiplier of 200%. Also included are restricted stock units granted under the 2020 OIP, which are paid out in shares of Alliant Energy’s common stock at the expiration of a three-year time-vesting period.
(b)All of the available shares under the 2020 OIP may be issued as awards in the form of shares of Alliant Energy’s common stock, restricted stock, restricted stock units, performance shares, performance units and other stock-based or cash-based awards. As of December 31, 2020, there were performance shares and restricted stock units (performance- and time-vesting) outstanding under the 2020 OIP.
(c)As of December 31, 2020, there were 380,542 shares of Alliant Energy’s common stock held under the DCP, which is described in Note 13(c).
(d)There is no limit on the number of shares of Alliant Energy’s common stock that may be held under the DCP.
The remainder of the information required by Item 12 is incorporated herein by reference to the relevant information in the 2021 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s fiscal year.
IPL AND WPL
None of IPL’s directors or executive officers own any shares of preferred stock in IPL. The remainder of the information required by Item 12 is incorporated herein by reference to the relevant information in the 2021 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of IPL’s and WPL’s fiscal years.

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ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE
The information required by Item 13 for each of Alliant Energy, IPL and WPL is incorporated herein by reference to the relevant information in the 2021 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s, IPL’s and WPL’s fiscal years.
ITEM 14. PRINCIPAL ACCOUNTING FEES AND SERVICES
ALLIANT ENERGY
The information required by Item 14 is incorporated herein by reference to the relevant information in the 2021 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s fiscal year.
IPL AND WPL
Each of IPL’s and WPL’s Audit Committee of the Board of Directors has adopted a policy that requires advance approval of all audit, audit-related, tax and other permitted services performed by the independent registered public accounting firm. The policy provides for pre-approval by the Audit Committee of specifically defined audit and non-audit services after the Audit Committee is provided with the appropriate level of details regarding the specific services to be provided. The policy does not permit delegation of the Audit Committee’s authority to management. In the event the need for specific services arises between Audit Committee meetings, the Audit Committee has delegated to the Chairperson of the Audit Committee authority to approve permitted services provided that the Chairperson reports any decisions to the Audit Committee at its next scheduled meeting. The principal accounting fees billed to Alliant Energy by its independent registered public accounting firm, all of which were approved in advance by the Audit Committee, directly related and allocated to IPL and WPL were as follows (in thousands):

| IPL |  | WPL
| 2020 |  | 2019 |  | 2020 |  | 2019
| Fees |  | % of Total |  | Fees |  | % of Total |  | Fees |  | % of Total |  | Fees |  | % of Total
Audit fees | $1,331 |  | 96% |  | $1,584 |  | 89% |  | $947 |  | 89% |  | $1,116 |  | 92%
Audit-related fees | 51 |  | 4% |  | 134 |  | 8% |  | 39 |  | 4% |  | 37 |  | 3%
Tax fees | 4 |  | —% |  | 52 |  | 3% |  | 78 |  | 7% |  | 56 |  | 5%
All other fees | 3 |  | —% |  | 2 |  | —% |  | 2 |  | —% |  | 1 |  | —%
| $1,389 |  | 100% |  | $1,772 |  | 100% |  | $1,066 |  | 100% |  | $1,210 |  | 100%

IPL’s and WPL’s audit fees for 2020 and 2019 consisted of the respective fees billed for the audits of the financial statements of IPL and its subsidiary and WPL and its subsidiary, for reviews of financial statements included in Form 10-Q filings, and for services normally provided in connection with statutory and regulatory filings, such as financing transactions. IPL’s and WPL’s audit fees also included their respective portion of fees for the 2020 and 2019 audits of Alliant Energy’s financial statements and effectiveness of internal controls over financial reporting. IPL’s and WPL’s audit-related fees for 2020 and 2019 consisted of the fees billed for services rendered related to employee benefits plan audits and other attest services. IPL’s and WPL’s tax fees for 2020 and 2019 consisted of the fees billed for professional services rendered for tax compliance, tax advice and tax planning, including all services performed by the tax professional staff of affiliates of the independent registered public accounting firm, except those rendered in connection with the audit. All other fees for 2020 and 2019 for IPL and WPL consisted of license fees for accounting research software products, and with respect to 2020, virtual seminars. The Audit Committee does not consider the provision of non-audit services by the independent registered public accounting firm described above to be incompatible with maintaining independence of the independent registered public accounting firm.

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PART IV
ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES
(1)Consolidated Financial Statements - Refer to Item 8 Financial Statements and Supplementary Data.
(2)Financial Statement Schedules -
SCHEDULE I - CONDENSED PARENT COMPANY FINANCIAL STATEMENTS

ALLIANT ENERGY CORPORATION (Parent Company Only) | Year Ended December 31,
CONDENSED STATEMENTS OF INCOME | 2020 |  | 2019 |  | 2018
| (in millions)
Operating expenses | $7 |  |  | $2 |  |  | $5 |
Operating loss | (7) |  |  | (2) |  |  | (5) |
Other (income) and deductions: |  |  |  |  |
Equity earnings from consolidated subsidiaries | (625) |  |  | (562) |  |  | (523) |
Interest expense | 2 |  |  | 9 |  |  | 4 |
Other | 4 |  |  | 7 |  |  | 2 |
Total other (income) and deductions | (619) |  |  | (546) |  |  | (517) |
Income before income taxes | 612 |  |  | 544 |  |  | 512 |
Income tax benefit | (4) |  |  | (15) |  |  | (1) |
Net income | $616 |  |  | $559 |  |  | $513 |

Refer to accompanying Notes to Condensed Financial Statements.

ALLIANT ENERGY CORPORATION (Parent Company Only) | December 31,
CONDENSED BALANCE SHEETS | 2020 |  | 2019
| (in millions)
ASSETS |  |  |
Current assets: |  |  |
Notes receivable from affiliated companies | $32 |  |  | $27 |
Other | 5 |  |  | 6 |
Total current assets | 37 |  |  | 33 |
Investments: |  |  |
Investments in consolidated subsidiaries | 6,664 |  |  | 6,017 |
Other | 2 |  |  | 1 |
Total investments | 6,666 |  |  | 6,018 |
Other assets | 88 |  |  | 89 |
Total assets | $6,791 |  |  | $6,140 |

LIABILITIES AND EQUITY |  |  |
Current liabilities: |  |  |
Commercial paper | $132 |  |  | $169 |
Notes payable to affiliated companies | 937 |  |  | 731 |
Other | 29 |  |  | 19 |
Total current liabilities | 1,098 |  |  | 919 |
Other liabilities | 2 |  |  | 15 |
Common equity: |  |  |
Common stock and additional paid-in capital | 2,706 |  |  | 2,448 |
Retained earnings | 2,996 |  |  | 2,766 |
Accumulated other comprehensive income | — |  |  | 2 |
Shares in deferred compensation trust | (11) |  |  | (10) |
Total common equity | 5,691 |  |  | 5,206 |
Total liabilities and equity | $6,791 |  |  | $6,140 |

Refer to accompanying Notes to Condensed Financial Statements.

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ALLIANT ENERGY CORPORATION (Parent Company Only) | Year Ended December 31,
CONDENSED STATEMENTS OF CASH FLOWS | 2020 |  | 2019 |  | 2018
| (in millions)
Net cash flows from operating activities | $396 |  |  | $305 |  |  | $311 |
Cash flows used for investing activities: |  |  |  |  |
Capital contributions to consolidated subsidiaries | (429) |  |  | (250) |  |  | (625) |
Net change in notes receivable from and payable to affiliates | 201 |  |  | 8 |  |  | 441 |
Net cash flows used for investing activities | (228) |  |  | (242) |  |  | (184) |
Cash flows used for financing activities: |  |  |  |  |
Common stock dividends | (377) |  |  | (338) |  |  | (312) |
Proceeds from issuance of common stock, net | 247 |  |  | 390 |  |  | 197 |
Net change in commercial paper | (37) |  |  | (116) |  |  | (10) |
Other | (1) |  |  | 1 |  |  | (2) |
Net cash flows used for financing activities | (168) |  |  | (63) |  |  | (127) |
Net increase (decrease) in cash, cash equivalents and restricted cash | — |  |  | — |  |  | — |
Cash, cash equivalents and restricted cash at beginning of period | — |  |  | — |  |  | — |
Cash, cash equivalents and restricted cash at end of period | $— |  |  | $— |  |  | $— |
Supplemental cash flows information: |  |  |  |  |
Cash (paid) refunded during the period for: |  |  |  |  |
Interest | ($2) |  |  | ($9) |  |  | ($4) |
Income taxes, net | 10 |  |  | 14 |  |  | 5 |

Refer to accompanying Notes to Condensed Financial Statements.
ALLIANT ENERGY CORPORATION
(Parent Company Only)
NOTES TO CONDENSED FINANCIAL STATEMENTS
Pursuant to rules and regulations of the SEC, the Condensed Financial Statements of Alliant Energy Corporation (Parent Company Only) do not reflect all of the information and notes normally included with financial statements prepared in accordance with GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the Financial Statements and related Notes included in the combined 2020 Form 10-K, Part II, Item 8, which is incorporated herein by reference.
In the Condensed Financial Statements of Alliant Energy Corporation (Parent Company Only), investments in subsidiaries are accounted for using the equity method.

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SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

|  |  |  | Additions |  |
| Balance, | Charged to | Charged to Other |  | Balance,
Description | January 1 | Expense | Accounts (a) | Deductions (b) | December 31
| (in millions)

Valuation and Qualifying Accounts Which are Deducted in the Balance Sheet from the Assets to Which They Apply:

| Accumulated Provision for Uncollectible Accounts: |  |  |  |
|  | Alliant Energy (c) |  |  |  |  |
|  |  | Year ended December 31, 2020 | $7 | $25 | $9 | $23 | $18
|  |  | Year ended December 31, 2019 | 10 | 17 | 2 | 22 | 7
|  |  | Year ended December 31, 2018 | 12 | 21 | 1 | 24 | 10
|  | IPL (c) |  |  |  |
|  |  | Year ended December 31, 2020 | $1 | $18 | $— | $18 | $1
|  |  | Year ended December 31, 2019 | 3 | 16 | — | 18 | 1
|  |  | Year ended December 31, 2018 | 1 | 21 | — | 19 | 3
|  | WPL |  |  |  |
|  |  | Year ended December 31, 2020 | $6 | $7 | $9 | $5 | $17
|  |  | Year ended December 31, 2019 | 7 | 1 | 2 | 4 | 6
|  |  | Year ended December 31, 2018 | 11 | — | 1 | 5 | 7

Note: The above provisions relate to various customer, notes and other receivable balances included in various line items on the respective balance sheets.
(a)Accumulated provision for uncollectible accounts: In accordance with its regulatory treatment, certain amounts provided by WPL are recorded in regulatory assets.
(b)Deductions are of the nature for which the reserves were created. In the case of the accumulated provision for uncollectible accounts, deductions from this reserve are reduced by recoveries of amounts previously written off.
(c)Refer to Note 5(b) for discussion of IPL’s sales of accounts receivable program.
NOTE: All other schedules are omitted because they are not applicable or not required, or because that required information is shown either in the financial statements or in the notes thereto.
(3) Exhibits Required by SEC Regulation S-K - Pursuant to Item 601(b)(4)(iii) of Regulation S-K, the registrants agree to furnish to the SEC, upon request, any instrument defining the rights of holders of unregistered long-term debt not filed as an exhibit to this combined Form 10-K. No such instrument authorizes securities in excess of 10% of the total assets of Alliant Energy, IPL or WPL, as the case may be. The following exhibits for Alliant Energy, IPL and WPL are filed herewith or incorporated herein by reference.

Exhibit Number | Description
3.1 | Restated Articles of Incorporation of Alliant Energy, as amended (incorporated by reference to Exhibit 4.1 to Alliant Energy’s Registration Statement on Form S-8 (Reg. No. 333-117654))
3.1a | Articles of Amendment to Restated Articles of Incorporation of Alliant Energy, as amended, effective May 4, 2016 (incorporated by reference to Exhibit 3.1 to Alliant Energy’s Form 10-Q for the quarter ended March 31, 2016 (File No. 1-9894))
3.2 | Amended and Restated Bylaws of Alliant Energy, effective October 27, 2020 (incorporated by reference to Exhibit 3.1 to Alliant Energy’s Form 8-K, filed October 29, 2020 (File No. 1-9894))
3.3 | Amended and Restated Articles of Incorporation of WPL, effective May 9, 2013 (incorporated by reference to Exhibit 3.4 to WPL’s Form 8-K, filed May 13, 2013 (File No. 0-337))
3.4 | Amended and Restated Bylaws of WPL, effective October 27, 2020 (incorporated by reference to Exhibit 3.3 to WPL’s Form 8-K, filed October 29, 2020 (File No. 0-337))
3.5 | Amended and Restated Articles of Incorporation of IPL, effective May 10, 2013 (incorporated by reference to Exhibit 3.2 to IPL’s Form 8-K, filed May 13, 2013 (File No. 1-4117))
3.6 | Amended and Restated Bylaws of IPL, effective October 27, 2020 (incorporated by reference to Exhibit 3.2 to IPL’s Form 8-K, filed October 29, 2020 (File No. 1-4117))
4.1 | Five-Year Master Credit Agreement, dated as of August 16, 2017, among Alliant Energy, IPL, WPL, Wells Fargo Bank, National Association (N.A.) and the lender parties set forth therein (incorporated by reference to Exhibit 4.1 to Alliant Energy’s Form 8-K, filed August 21, 2017 (File No. 1-9894))
4.2 | Senior Note Indenture, dated as of September 30, 2009, between Alliant Energy and Wells Fargo Bank, N.A. (incorporated by reference to Exhibit 4.28 to Alliant Energy’s Registration Statement on Form S-3 (Reg. No. 333-162214))
4.3 | Indenture, dated as of June 12, 2018, among AEF, Alliant Energy, as guarantor, and The Bank of New York Mellon Trust Company, N.A., as trustee (incorporated by reference to Exhibit 4.1 to Alliant Energy’s Form 8-K, filed June 12, 2018 (File No. 1-9894))
4.4 | Indenture, dated as of November 20, 2020, among AEF, Alliant Energy as guarantor, and The Bank of New York Mellon Trust Company, N.A., as trustee (incorporated by reference to Exhibit 4.1 to Alliant Energy’s Form 8-K, filed November 23, 2020 (File No. 1-9894)
4.5 | Indenture, dated as of June 20, 1997, between WPL and Wells Fargo Bank, N.A., Successor, as Trustee (incorporated by reference to Exhibit 4.33 to Amendment No. 2 to WPL’s Registration Statement on Form S-3 (Reg. No. 033-60917))

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Exhibit Number | Description
4.6 | Officers’ Certificate, dated as of July 28, 2004, creating WPL’s 6.25% Debentures due July 31, 2034 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed August 2, 2004 (File No. 0-337))
4.7 | Officers’ Certificate, dated as of August 8, 2007, creating WPL’s 6.375% Debentures due August 15, 2037 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed August 9, 2007 (File No. 0-337))
4.8 | Officer’s Certificate, dated as of October 1, 2008, creating WPL’s 7.60% Debentures due October 1, 2038 (incorporated by reference to Exhibit 4.2 to WPL’s Form 8-K, filed October 2, 2008 (File No. 0-337))
4.9 | Officers’ Certificate, dated as of November 19, 2012, creating WPL’s 2.25% Debentures due November 15, 2022 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed November 19, 2012 (File No. 0-337))
4.10 | Officers’ Certificate, dated as of October 14, 2014, creating WPL’s 4.10% Debentures due October 15, 2044 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed October 14, 2014 (File No. 0-337))
4.11 | Officers’ Certificate, dated as of October 10, 2017, creating WPL’s 3.05% Debentures due October 15, 2027 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed October 10, 2017 (File No. 0-337))
4.12 | Officers’ Certificate, dated as of June 24, 2019, creating WPL’s 3.00% Debentures due July 1, 2029 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed June 24, 2019 (File No. 0-337))
4.13 | Officers’ Certificate, dated as of April 2, 2020, creating WPL’s 3.65% Debentures due April 1, 2050 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed April 2, 2020 (File No. 0-337))
4.14 | Indenture (For Senior Unsecured Debt Securities), dated as of August 20, 2003, between IPL and The Bank of New York Mellon Trust Co., N.A. (f/k/a The Bank of New York Trust Co., N.A.), as Trustee (incorporated by reference to Exhibit 4.11 to IPL’s Registration Statement on Form S-3 (Reg. No. 333-108199))
4.15 | Officer’s Certificate, dated as of October 14, 2003, creating IPL’s 6.45% Senior Debentures due October 15, 2033 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed October 15, 2003 (File No. 1-4117))
4.16 | Officer’s Certificate, dated as of May 3, 2004, creating IPL’s 6.30% Senior Debentures due May 1, 2034 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed May 5, 2004 (File No. 1-4117))
4.16a | Officer’s Certificate, dated as of August 2, 2004, reopening IPL’s 6.30% Senior Debentures due May 1, 2034 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed August 5, 2004 (File No. 1-4117))
4.17 | Officer’s Certificate, dated as of July 18, 2005, creating IPL’s 5.50% Senior Debentures due July 15, 2025 (incorporated by reference to Exhibit 4 to IPL’s Form 8-K, filed July 19, 2005 (File No. 1-4117))
4.18 | Officer’s Certificate, dated as of July 7, 2009, creating IPL’s 6.25% Senior Debentures due July 15, 2039 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed July 8, 2009 (File No. 1-4117))
4.19 | Officer’s Certificate, dated as of October 8, 2013, creating IPL’s 4.70% Senior Debentures due October 15, 2043 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed October 8, 2013 (File No. 1-4117))
4.20 | Officer’s Certificate, dated as of November 24, 2014, creating IPL’s 3.25% Senior Debentures due December 1, 2024 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed November 24, 2014 (File No. 1-4117))
4.20a | Officer’s Certificate, dated as of November 15, 2017, reopening IPL’s 3.25% Senior Debentures due December 1, 2024 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed November 15, 2017 (File No. 1-4117))
4.21 | Officer’s Certificate, dated as of August 18, 2015, creating IPL’s 3.40% Senior Debentures due August 15, 2025 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed August 18, 2015 (File No. 1-4117))
4.22 | Officer’s Certificate, dated as of September 15, 2016, creating IPL’s 3.70% Senior Debentures due September 15, 2046 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed September 15, 2016 (File No. 1-4117))
4.23 | Officer’s Certificate, dated as of September 26, 2018, creating IPL’s 4.10% Senior Debentures due September 26, 2028 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed September 26, 2018 (File No. 1-4117))
4.24 | Officer’s Certificate, dated as of April 1, 2019, creating IPL’s 3.60% Senior Debentures due April 1, 2029 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed April 1, 2019 (File No. 1-4117))
4.25 | Officer’s Certificate, dated as of September 26, 2019, creating IPL’s 3.50% Senior Debentures due September 30, 2049 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed September 26, 2019 (File No. 1-4117))
4.26 | Officer’s Certificate, dated as of June 2, 2020, creating IPL’s 2.3% Senior Debentures due June 1, 2030 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed June 2, 2020 (File No. 1-4117))
4.27 | Description of Common Stock of Alliant Energy (incorporated by reference to Exhibit 4.26 to Alliant Energy’s Form 10-K for the year 2019 (File No. 1-9894))
4.28 | Description of 5.100% Series D Cumulative Perpetual Preferred Stock of IPL (incorporated by reference to Exhibit 4.27 to Alliant Energy’s Form 10-K for the year 2019 (File No. 1-4117))
4.29 | Form of Preferred Stock Certificate of IPL (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed March 20, 2013 (File No. 1-4117))
10.1 | Term Loan Credit Agreement, dated as of March 3, 2020, among AEF, Alliant Energy, KeyBank N.A. and the lender parties set forth therein (incorporated by reference to Exhibit 10.1 to Alliant Energy’s Form 8-K, filed March 5, 2020 (File No. 1-9894))
10.2# | Amended and Restated OIP, amended in 2015 (incorporated by reference to Appendix A to Alliant Energy’s definitive proxy statement filed on Schedule 14A on March 24, 2015 (File No. 1-9894))
10.2a# | Amendment to the Amended and Restated OIP (incorporated by reference to Exhibit 10.6a to Alliant Energy’s Form 10-K for the year 2018 (File No. 1-9894))
10.2b# | Form of Performance Share Agreement pursuant to the Amended and Restated OIP, amended in 2015 (incorporated by reference to Exhibit 10.4a to Alliant Energy’s Form 10-K for the year 2015 (File No. 1-9894))
10.2c# | Form of Performance Share Agreement pursuant to the Amended and Restated OIP, amended in 2019 (incorporated by reference to Exhibit 10.6c to Alliant Energy’s Form 10-K for the year 2018 (File No. 1-9894))
10.2d# | Form of Restricted Stock Unit Agreement pursuant to the Amended and Restated OIP, amended in 2015 (incorporated by reference to Exhibit 10.4b to Alliant Energy’s Form 10-K for the year 2015 (File No. 1-9894))
10.2e# | Form of Restricted Stock Unit Agreement pursuant to the Amended and Restated OIP, amended in 2019 (incorporated by reference to Exhibit 10.6e to Alliant Energy’s Form 10-K for the year 2018 (File No. 1-9894))

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Exhibit Number | Description
10.2f# | Form of Performance Restricted Stock Unit Agreement pursuant to the Amended and Restated OIP, amended in 2015 (incorporated by reference to Exhibit 10.4c to Alliant Energy’s Form 10-K for the year 2015 (File No. 1-9894))
10.2g# | Form of Performance Restricted Stock Unit Agreement pursuant to the Amended and Restated OIP, amended in 2019 (incorporated by reference to Exhibit 10.6g to Alliant Energy’s Form 10-K for the year 2018 (File No. 1-9894))
10.3 | Alliant Energy 2020 Omnibus Incentive Plan (incorporated by reference to Appendix A to Alliant Energy’s definitive proxy statement filed on Schedule 14A on April 9, 2020 (File No. 1-9894))
10.3a# | Form of Performance Share Agreement pursuant to the Alliant Energy 2020 Omnibus Incentive Plan (incorporated by reference to Exhibit 10.1a to Alliant Energy’s Form 10-Q for the quarter ended June 30, 2020 (File No. 1-9894))
10.3b# | Form of Restricted Stock Unit Agreement pursuant to the Alliant Energy 2020 Omnibus Incentive Plan (incorporated by reference to Exhibit 10.1b to Alliant Energy’s Form 10-Q for the quarter ended June 30, 2020 (File No. 1-9894))
10.3c# | Form of Performance Restricted Stock Unit Agreement pursuant to the Alliant Energy 2020 Omnibus Incentive Plan (incorporated by reference to Exhibit 10.1c to Alliant Energy’s Form 10-Q for the quarter ended June 30, 2020 (File No. 1-9894))
10.4# | DCP, as amended and restated effective January 1, 2011 (incorporated by reference to Exhibit 10.1 to Alliant Energy’s Form 8-K, filed December 14, 2010 (File No. 1-9894))
10.4a# | Amendment to the DCP, as amended and restated (incorporated by reference to Exhibit 10.2 to Alliant Energy’s Form 8-K, filed December 5, 2011 (File No. 1-9894))
10.5# | IES Industries Inc. Amended and Restated Key Employee Deferred Compensation Agreement, as amended (incorporated by reference to Exhibit 10.7 to Alliant Energy’s Form 10-K for the year 2015 (File No. 1-9894))
10.6# | Alliant Energy Rabbi Trust Agreement for DCPs (incorporated by reference to Exhibit 10.19 to Alliant Energy’s Form 10-K for the year 2005 (File No. 1-9894))
10.6a# | Amendment to the Alliant Energy Rabbi Trust Agreement for DCPs (incorporated by reference to Exhibit 10.2 to Alliant Energy’s Form 10-Q for the quarter ended June 30, 2015 (File No. 1-9894))
10.6b# | Second Amendment to the Alliant Energy Rabbi Trust Agreement for DCPs (incorporated by reference to Exhibit 10.3 to Alliant Energy’s Form 10-Q for the quarter ended June 30, 2015 (File No. 1-9894))
10.7# | Alliant Energy Excess Retirement Plan (incorporated by reference to Exhibit 10.1 to Alliant Energy’s Form 10-Q for the quarter ended September 30, 2008 (File No. 1-9894))
10.7a# | Amendment to the Alliant Energy Excess Retirement Plan (incorporated by reference to Exhibit 10.4 to Alliant Energy’s Form 8-K, filed December 5, 2011 (File No. 1-9894))
10.8# | Form of Supplemental Retirement Plan (SRP) Agreement by and between Alliant Energy and J.O. Larsen (incorporated by reference to Exhibit 10.3 to Alliant Energy’s Form 8-K, filed December 12, 2008 (File No. 1-9894))
10.9# | Alliant Energy Defined Contribution SRP (incorporated by reference to Exhibit 10.1 to Alliant Energy’s Form 10-Q for the quarter ended September 30, 2010 (File No. 1-9894))
10.9a# | Amendment to the Alliant Energy Defined Contribution SRP (incorporated by reference to Exhibit 10.3 to Alliant Energy’s Form 8-K, filed December 5, 2011 (File No. 1-9894))
10.9b# | Amendment to the Alliant Energy Defined Contribution SRP (incorporated by reference to Exhibit 10.1 to Alliant Energy’s Form 8-K, filed March 12, 2014 (File No. 1-9894))
10.10# | Form of Key Executive Employment and Severance Agreement (KEESA), by and between Alliant Energy and each of J.H. Gallegos, J.O. Larsen, R.J. Durian, D.A. de Leon and T.L. Kouba (incorporated by reference to Exhibit 10.3 to Alliant Energy’s Form 10-Q for the quarter ended June 30, 2008 (File No. 1-9894))
10.10a# | Form of Amendment to KEESA, by and between Alliant Energy and each of J.H. Gallegos, J.O. Larsen, R.J. Durian, D.A. de Leon and T.L. Kouba (incorporated by reference to Exhibit 10.1 to Alliant Energy’s Form 10-Q for the quarter ended September 30, 2015 (File No. 1-9894))
10.11# | Form of Amendment Number One to KEESA, by and between Alliant Energy and each of J.H. Gallegos, J.O. Larsen, R.J. Durian, D.A. de Leon and T.L. Kouba (incorporated by reference to Exhibit 10.6 to Alliant Energy’s Form 8-K, filed December 5, 2011 (File No. 1-9894))
10.12# | Executive Officer Severance Benefit Plan, as amended and restated, effective October 29, 2018 (incorporated by reference to Exhibit 10.1 to Alliant Energy’s Form 10-Q for the quarter ended September 30, 2018 (File No. 1-9894))
10.13# | Terms of Alliant Energy Executive Performance Pay Plan (incorporated by reference to Exhibit 10.18 to Alliant Energy’s Form 10-K for the year 2015 (File No. 1-9894))
10.14# | Summary of Compensation and Benefits for Non-Employee Directors of Alliant Energy, IPL and WPL, effective January 1, 202 1
21.1 | Subsidiaries of Alliant Energy
23.1 | Consent of Independent Registered Public Accounting Firm for Alliant Energy
23.2 | Consent of Independent Registered Public Accounting Firm for IPL
23.3 | Consent of Independent Registered Public Accounting Firm for WPL
31.1 | Certification of the Chief Executive Officer for Alliant Energy
31.2 | Certification of the Chief Financial Officer for Alliant Energy
31.3 | Certification of the Chief Executive Officer for IPL
31.4 | Certification of the Chief Financial Officer for IPL
31.5 | Certification of the Chief Executive Officer for WPL
31.6 | Certification of the Chief Financial Officer for WPL
32.1 | Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for Alliant Energy
32.2 | Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for IPL
32.3 | Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for WPL
101.INS | Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document

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Table of Cont ents

Exhibit Number | Description
101.SCH | Inline XBRL Taxonomy Extension Schema Document
101.CAL | Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB | Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE | Inline XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF | Inline XBRL Taxonomy Extension Definition Linkbase Document
104 | Cover Page Interactive Data File (embedded within the Inline XBRL document)

# A management contract or compensatory plan or arrangement.
ITEM 16. FORM 10-K SUMMARY
None.

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Table of Cont ents
SIGNATURES
Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrants have duly caused this report to be signed on their behalf by the undersigned, thereunto duly authorized on the 19th day of February 2021.

ALLIANT ENERGY |  | INTERSTATE POWER |  | WISCONSIN POWER
CORPORATION |  | AND LIGHT COMPANY |  | AND LIGHT COMPANY
By: /s/ John O. Larsen |  | By: /s/ John O. Larsen |  | By: /s/ John O. Larsen
John O. Larsen |  | John O. Larsen |  | John O. Larsen
Chairman, President and Chief Executive Officer |  | Chairman and Chief Executive Officer |  | Chairman and Chief Executive Officer

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the Registrants and in the capacities indicated on the 19th day of February 2021.

ALLIANT ENERGY |  | INTERSTATE POWER |  | WISCONSIN POWER
CORPORATION |  | AND LIGHT COMPANY |  | AND LIGHT COMPANY
/s/ John O. Larsen |  | /s/ John O. Larsen |  | /s/ John O. Larsen
John O. Larsen |  | John O. Larsen |  | John O. Larsen
Chairman, President, Chief Executive Officer and Director (Principal Executive Officer) |  | Chairman, Chief Executive Officer and Director (Principal Executive Officer) |  | Chairman, Chief Executive Officer and Director (Principal Executive Officer)
/s/ Robert J. Durian |  | /s/ Robert J. Durian |  | /s/ Robert J. Durian
Robert J. Durian |  | Robert J. Durian |  | Robert J. Durian
Executive Vice President and Chief Financial Officer (Principal Financial Officer) |  | Executive Vice President and Chief Financial Officer (Principal Financial Officer) |  | Executive Vice President and Chief Financial Officer (Principal Financial Officer)
/s/ Benjamin M. Bilitz |  | /s/ Benjamin M. Bilitz |  | /s/ Benjamin M. Bilitz
Benjamin M. Bilitz |  | Benjamin M. Bilitz |  | Benjamin M. Bilitz
Chief Accounting Officer and Controller (Principal Accounting Officer) |  | Chief Accounting Officer and Controller (Principal Accounting Officer) |  | Chief Accounting Officer and Controller (Principal Accounting Officer)
/s/ Patrick E. Allen |  | /s/ Patrick E. Allen |  | /s/ Patrick E. Allen
Patrick E. Allen, Director |  | Patrick E. Allen, Director |  | Patrick E. Allen, Director
/s/ Michael D. Garcia |  | /s/ Michael D. Garcia |  | /s/ Michael D. Garcia
Michael D. Garcia, Director |  | Michael D. Garcia, Director |  | Michael D. Garcia, Director
/s/ Singleton B. McAllister |  | /s/ Singleton B. McAllister |  | /s/ Singleton B. McAllister
Singleton B. McAllister, Director |  | Singleton B. McAllister, Director |  | Singleton B. McAllister, Director
/s/ Roger K. Newport |  | /s/ Roger K. Newport |  | /s/ Roger K. Newport
Roger K. Newport, Director |  | Roger K. Newport, Director |  | Roger K. Newport, Director
/s/ Thomas F. O’Toole |  | /s/ Thomas F. O’Toole |  | /s/ Thomas F. O’Toole
Thomas F. O’Toole, Director |  | Thomas F. O’Toole, Director |  | Thomas F. O’Toole, Director
/s/ Dean C. Oestreich |  | /s/ Dean C. Oestreich |  | /s/ Dean C. Oestreich
Dean C. Oestreich, Director |  | Dean C. Oestreich, Director |  | Dean C. Oestreich, Director
/s/ Carol P. Sanders |  | /s/ Carol P. Sanders |  | /s/ Carol P. Sanders
Carol P. Sanders, Director |  | Carol P. Sanders, Director |  | Carol P. Sanders, Director
/s/ Susan D. Whiting |  | /s/ Susan D. Whiting |  | /s/ Susan D. Whiting
Susan D. Whiting, Director |  | Susan D. Whiting, Director |  | Susan D. Whiting, Director

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