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Commitments And Contingencies | 12 Months Ended
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Dec. 31, 2024
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPL’s and WPL’s expansion of energy storage, and improvements at WPL’s natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility. At December 31, 2024, Alliant Energy’s, IPL’s, and WPL’s minimum future commitments in 2025 for these projects were $448 million, $294 million, and $153 million, respectively.(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, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions):
Alliant Energy | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $268 |  | $177 |  | $130 |  | $102 |  | $84 |  | $120 |  | $881
Coal | 75 |  | 33 |  | 22 |  | 5 |  | — |  | — |  | 135
Other (a) | 51 |  | 20 |  | 7 |  | 7 |  | 2 |  | 22 |  | 109
| $394 |  | $230 |  | $159 |  | $114 |  | $86 |  | $142 |  | $1,125
IPL | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $160 |  | $104 |  | $85 |  | $64 |  | $49 |  | $20 |  | $482
Coal | 34 |  | 19 |  | 10 |  | 5 |  | — |  | — |  | 68
Other (a) | 18 |  | 2 |  | 2 |  | 2 |  | 2 |  | 21 |  | 47
| $212 |  | $125 |  | $97 |  | $71 |  | $51 |  | $41 |  | $597
WPL | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $108 |  | $73 |  | $45 |  | $38 |  | $35 |  | $100 |  | $399
Coal | 41 |  | 14 |  | 12 |  | — |  | — |  | — |  | 67
Other (a) | 22 |  | 1 |  | — |  | — |  | — |  | — |  | 23
| $171 |  | $88 |  | $57 |  | $38 |  | $35 |  | $100 |  | $489
(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2024. (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.(d) Guarantees and Indemnifications - Whiting Petroleum Corporation (Whiting Petroleum) - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum, an independent oil and gas company. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, has guaranteed 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. Whiting Petroleum previously completed bankruptcy proceedings and business combinations, which substantially reduce the likelihood that Alliant Energy will be obligated to make any payments under these guarantees. As of December 31, 2024, the currently known partnership obligations for the abandonment obligations are estimated at $54 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy is not currently aware of, nor does it currently expect to incur in the future, any material liabilities related to these guarantees and therefore has not recognized any material liabilities related to these guarantees as of December 31, 2024 and 2023. 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 $43 million as of December 31, 2024 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, 2024 and 2023. Transfers of Renewable Tax Credits - In 2023 and 2024, IPL and WPL entered into agreements to transfer renewable tax credits from certain wind, solar and energy storage facilities to other corporate taxpayers in exchange for cash. As of December 31, 2024, IPL and WPL provided indemnifications associated with $193 million and $121 million, respectively, of proceeds for renewable tax credits transferred to other corporate taxpayers in the event of an adverse interpretation of tax law, including whether the related tax credits meet the qualification requirements. Alliant Energy, IPL and WPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. (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. Manufactured Gas Plant 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 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, 2024, 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):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs | $7 |  | - | $28 |  | $5 |  | - | $17 |  | $2 |  | - | $11
Current and non-current environmental liabilities | $12 |  | $7 |  | $5
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 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: CSAPR, Effluent Limitation Guidelines, CCR Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the CAA. (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 large 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, including reimbursement of transmission costs from large load growth customers, 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, different 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 different counterparties, 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 1 4 for details of allowances for expected credit losses and credit risk-related contingent features, respectively. (g) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with FERC requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2022, the U.S. Court of Appeals for the District of Columbia vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings. As a result of the 2022 court decision, Alliant Energy recorded a $6 million reduction in “Equity income from unconsolidated investments” in its income statement in 2022 to reflect the then-anticipated reduction in the base return on equity authorized for the MISO transmission owners. In October 2024, FERC issued an order reducing the base return on equity authorized for MISO transmission owners to 9.98%, and as a result, the MISO transmission owners will provide refunds based on the 9.98% base return on equity, with interest, for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016, which did not result in any material impacts on Alliant Energy’s results of operations or financial condition in 2024. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs; however, Alliant Energy is currently unable to predict with certainty the future outcome or impact of any further changes.
IPL [Member] |
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPL’s and WPL’s expansion of energy storage, and improvements at WPL’s natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility. At December 31, 2024, Alliant Energy’s, IPL’s, and WPL’s minimum future commitments in 2025 for these projects were $448 million, $294 million, and $153 million, respectively.(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, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions):
Alliant Energy | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $268 |  | $177 |  | $130 |  | $102 |  | $84 |  | $120 |  | $881
Coal | 75 |  | 33 |  | 22 |  | 5 |  | — |  | — |  | 135
Other (a) | 51 |  | 20 |  | 7 |  | 7 |  | 2 |  | 22 |  | 109
| $394 |  | $230 |  | $159 |  | $114 |  | $86 |  | $142 |  | $1,125
IPL | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $160 |  | $104 |  | $85 |  | $64 |  | $49 |  | $20 |  | $482
Coal | 34 |  | 19 |  | 10 |  | 5 |  | — |  | — |  | 68
Other (a) | 18 |  | 2 |  | 2 |  | 2 |  | 2 |  | 21 |  | 47
| $212 |  | $125 |  | $97 |  | $71 |  | $51 |  | $41 |  | $597
WPL | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $108 |  | $73 |  | $45 |  | $38 |  | $35 |  | $100 |  | $399
Coal | 41 |  | 14 |  | 12 |  | — |  | — |  | — |  | 67
Other (a) | 22 |  | 1 |  | — |  | — |  | — |  | — |  | 23
| $171 |  | $88 |  | $57 |  | $38 |  | $35 |  | $100 |  | $489
(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2024. (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.(d) Guarantees and Indemnifications - Whiting Petroleum Corporation (Whiting Petroleum) - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum, an independent oil and gas company. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, has guaranteed 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. Whiting Petroleum previously completed bankruptcy proceedings and business combinations, which substantially reduce the likelihood that Alliant Energy will be obligated to make any payments under these guarantees. As of December 31, 2024, the currently known partnership obligations for the abandonment obligations are estimated at $54 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy is not currently aware of, nor does it currently expect to incur in the future, any material liabilities related to these guarantees and therefore has not recognized any material liabilities related to these guarantees as of December 31, 2024 and 2023. 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 $43 million as of December 31, 2024 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, 2024 and 2023. Transfers of Renewable Tax Credits - In 2023 and 2024, IPL and WPL entered into agreements to transfer renewable tax credits from certain wind, solar and energy storage facilities to other corporate taxpayers in exchange for cash. As of December 31, 2024, IPL and WPL provided indemnifications associated with $193 million and $121 million, respectively, of proceeds for renewable tax credits transferred to other corporate taxpayers in the event of an adverse interpretation of tax law, including whether the related tax credits meet the qualification requirements. Alliant Energy, IPL and WPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. (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. Manufactured Gas Plant 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 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, 2024, 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):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs | $7 |  | - | $28 |  | $5 |  | - | $17 |  | $2 |  | - | $11
Current and non-current environmental liabilities | $12 |  | $7 |  | $5
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 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: CSAPR, Effluent Limitation Guidelines, CCR Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the CAA. (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 large 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, including reimbursement of transmission costs from large load growth customers, 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, different 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 different counterparties, 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 1 4 for details of allowances for expected credit losses and credit risk-related contingent features, respectively. (g) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with FERC requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2022, the U.S. Court of Appeals for the District of Columbia vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings. As a result of the 2022 court decision, Alliant Energy recorded a $6 million reduction in “Equity income from unconsolidated investments” in its income statement in 2022 to reflect the then-anticipated reduction in the base return on equity authorized for the MISO transmission owners. In October 2024, FERC issued an order reducing the base return on equity authorized for MISO transmission owners to 9.98%, and as a result, the MISO transmission owners will provide refunds based on the 9.98% base return on equity, with interest, for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016, which did not result in any material impacts on Alliant Energy’s results of operations or financial condition in 2024. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs; however, Alliant Energy is currently unable to predict with certainty the future outcome or impact of any further changes.
WPL [Member] |
Commitments And Contingencies | COMMITMENTS AND CONTINGENCIES(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPL’s and WPL’s expansion of energy storage, and improvements at WPL’s natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility. At December 31, 2024, Alliant Energy’s, IPL’s, and WPL’s minimum future commitments in 2025 for these projects were $448 million, $294 million, and $153 million, respectively.(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, 2024, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions):
Alliant Energy | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $268 |  | $177 |  | $130 |  | $102 |  | $84 |  | $120 |  | $881
Coal | 75 |  | 33 |  | 22 |  | 5 |  | — |  | — |  | 135
Other (a) | 51 |  | 20 |  | 7 |  | 7 |  | 2 |  | 22 |  | 109
| $394 |  | $230 |  | $159 |  | $114 |  | $86 |  | $142 |  | $1,125
IPL | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $160 |  | $104 |  | $85 |  | $64 |  | $49 |  | $20 |  | $482
Coal | 34 |  | 19 |  | 10 |  | 5 |  | — |  | — |  | 68
Other (a) | 18 |  | 2 |  | 2 |  | 2 |  | 2 |  | 21 |  | 47
| $212 |  | $125 |  | $97 |  | $71 |  | $51 |  | $41 |  | $597
WPL | 2025 |  | 2026 |  | 2027 |  | 2028 |  | 2029 |  | Thereafter |  | Total
Natural gas | $108 |  | $73 |  | $45 |  | $38 |  | $35 |  | $100 |  | $399
Coal | 41 |  | 14 |  | 12 |  | — |  | — |  | — |  | 67
Other (a) | 22 |  | 1 |  | — |  | — |  | — |  | — |  | 23
| $171 |  | $88 |  | $57 |  | $38 |  | $35 |  | $100 |  | $489
(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2024. (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.(d) Guarantees and Indemnifications - Whiting Petroleum Corporation (Whiting Petroleum) - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum, an independent oil and gas company. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, has guaranteed 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. Whiting Petroleum previously completed bankruptcy proceedings and business combinations, which substantially reduce the likelihood that Alliant Energy will be obligated to make any payments under these guarantees. As of December 31, 2024, the currently known partnership obligations for the abandonment obligations are estimated at $54 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy is not currently aware of, nor does it currently expect to incur in the future, any material liabilities related to these guarantees and therefore has not recognized any material liabilities related to these guarantees as of December 31, 2024 and 2023. 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 $43 million as of December 31, 2024 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, 2024 and 2023. Transfers of Renewable Tax Credits - In 2023 and 2024, IPL and WPL entered into agreements to transfer renewable tax credits from certain wind, solar and energy storage facilities to other corporate taxpayers in exchange for cash. As of December 31, 2024, IPL and WPL provided indemnifications associated with $193 million and $121 million, respectively, of proceeds for renewable tax credits transferred to other corporate taxpayers in the event of an adverse interpretation of tax law, including whether the related tax credits meet the qualification requirements. Alliant Energy, IPL and WPL believe the likelihood of having to make any material cash payments under these indemnifications is remote. (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. Manufactured Gas Plant 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 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, 2024, 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):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs | $7 |  | - | $28 |  | $5 |  | - | $17 |  | $2 |  | - | $11
Current and non-current environmental liabilities | $12 |  | $7 |  | $5
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 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: CSAPR, Effluent Limitation Guidelines, CCR Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the CAA. (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 large 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, including reimbursement of transmission costs from large load growth customers, 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, different 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 different counterparties, 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 1 4 for details of allowances for expected credit losses and credit risk-related contingent features, respectively. (g) MISO Transmission Owner Return on Equity Complaints - A group of stakeholders, including MISO cooperative and municipal utilities, previously filed complaints with FERC requesting a reduction to the base return on equity authorized for MISO transmission owners, including ITC and ATC. In 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity authorized for the MISO transmission owners to 9.88% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2020, FERC issued orders in response to various rehearing requests and increased the base return on equity authorized for the MISO transmission owners from 9.88% to 10.02% for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016. In 2022, the U.S. Court of Appeals for the District of Columbia vacated FERC’s prior orders that established the base return on equity authorized for the MISO transmission owners and remanded the cases to FERC for further proceedings. As a result of the 2022 court decision, Alliant Energy recorded a $6 million reduction in “Equity income from unconsolidated investments” in its income statement in 2022 to reflect the then-anticipated reduction in the base return on equity authorized for the MISO transmission owners. In October 2024, FERC issued an order reducing the base return on equity authorized for MISO transmission owners to 9.98%, and as a result, the MISO transmission owners will provide refunds based on the 9.98% base return on equity, with interest, for November 12, 2013 through February 11, 2015, and subsequent to September 28, 2016, which did not result in any material impacts on Alliant Energy’s results of operations or financial condition in 2024. Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs; however, Alliant Energy is currently unable to predict with certainty the future outcome or impact of any further changes.

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