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Derivative Instruments | 12 Months Ended
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Dec. 31, 2024
Derivative [Line Items] |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Purpose - Derivative instruments were utilized for risk management purposes to mitigate pricing volatility for fuel used to supply natural gas-fired EGUs, natural gas supplied to retail customers, and purchased electricity, as well as optimize the value of natural gas pipeline capacity and electric generation, which may include swap, physical forward and option contracts. In addition, FTRs help manage transmission congestion costs in the MISO market. Risk policies are maintained that govern the use of such derivative instruments. Notional Amounts - As of December 31, 2024, 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):
| Electricity |  | FTRs |  | Natural Gas |  |  |  | Diesel Fuel
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  | Gallons |  | Years
Alliant Energy | 1,422 |  |  | 2025-2026 |  | 10,232 |  |  | 2025 |  | 147,894 |  |  | 2025-2032 |  |  |  |  |  | 2,520 |  |  | 2025
IPL | 383 |  |  | 2025-2026 |  | 3,551 |  |  | 2025 |  | 61,489 |  |  | 2025-2030 |  |  |  |  |  | — |  |  | —
WPL | 1,039 |  |  | 2025-2026 |  | 6,681 |  |  | 2025 |  | 86,405 |  |  | 2025-2032 |  |  |  |  |  | 2,520 |  |  | 2025
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
| 2024 |  | 2023 |  | 2024 |  | 2023 |  | 2024 |  | 2023
Current derivative assets | $41 |  | $44 |  | $29 |  | $30 |  | $12 |  | $14
Non-current derivative assets | 34 |  | 44 |  | 19 |  | 24 |  | 15 |  | 20
Current derivative liabilities | 26 |  | 51 |  | 11 |  | 22 |  | 15 |  | 29
Non-current derivative liabilities | 32 |  | 47 |  | 2 |  | 8 |  | 30 |  | 39
In 2024, Alliant Energy’s, IPL’s and WPL’s derivative liabilities decreased primarily due to settlements of natural gas contracts and higher natural gas prices. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets. 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 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, 2024 and 2023, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different th an 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, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets at December 31 as follows:
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
2024 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $75 |  | $64 |  | $48 |  | $43 |  | $27 |  | $21
Derivative liabilities | 58 |  | 47 |  | 13 |  | 8 |  | 45 |  | 39
2023 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 88 |  | 47 |  | 54 |  | 32 |  | 34 |  | 15
Derivative liabilities | 98 |  | 57 |  | 30 |  | 8 |  | 68 |  | 49
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. Interest Rate Derivative - In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026 to mitigate interest rate risk. Under the terms of the swap, AEF exchanged a variable interest rate for a fixed interest rate of 3.93% on a portion of its variable-rate term loan borrowings. The related interest rate derivative was valued based on quoted prices that utilize current market interest rate forecasts. As of both December 31, 2024 and 2023, $1 million of non-current interest rate derivative assets was recorded in “Deferred charges and other” on Alliant Energy’s balance sheets. This interest rate derivative was designated as a cash flow hedge, with changes in fair value recorded as other comprehensive income/loss. As of both December 31, 2024 and 2023, accumulated other comprehensive income included $1 million of income related to the interest rate swap. In 2024 and 2023, $4 million and $3 million, respectively, of reductions to interest expense were recorded in Alliant Energy’s income statement related to the interest rate swap.
IPL [Member] |
Derivative [Line Items] |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Purpose - Derivative instruments were utilized for risk management purposes to mitigate pricing volatility for fuel used to supply natural gas-fired EGUs, natural gas supplied to retail customers, and purchased electricity, as well as optimize the value of natural gas pipeline capacity and electric generation, which may include swap, physical forward and option contracts. In addition, FTRs help manage transmission congestion costs in the MISO market. Risk policies are maintained that govern the use of such derivative instruments. Notional Amounts - As of December 31, 2024, 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):
| Electricity |  | FTRs |  | Natural Gas |  |  |  | Diesel Fuel
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  | Gallons |  | Years
Alliant Energy | 1,422 |  |  | 2025-2026 |  | 10,232 |  |  | 2025 |  | 147,894 |  |  | 2025-2032 |  |  |  |  |  | 2,520 |  |  | 2025
IPL | 383 |  |  | 2025-2026 |  | 3,551 |  |  | 2025 |  | 61,489 |  |  | 2025-2030 |  |  |  |  |  | — |  |  | —
WPL | 1,039 |  |  | 2025-2026 |  | 6,681 |  |  | 2025 |  | 86,405 |  |  | 2025-2032 |  |  |  |  |  | 2,520 |  |  | 2025
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
| 2024 |  | 2023 |  | 2024 |  | 2023 |  | 2024 |  | 2023
Current derivative assets | $41 |  | $44 |  | $29 |  | $30 |  | $12 |  | $14
Non-current derivative assets | 34 |  | 44 |  | 19 |  | 24 |  | 15 |  | 20
Current derivative liabilities | 26 |  | 51 |  | 11 |  | 22 |  | 15 |  | 29
Non-current derivative liabilities | 32 |  | 47 |  | 2 |  | 8 |  | 30 |  | 39
In 2024, Alliant Energy’s, IPL’s and WPL’s derivative liabilities decreased primarily due to settlements of natural gas contracts and higher natural gas prices. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets. 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 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, 2024 and 2023, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different th an 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, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets at December 31 as follows:
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
2024 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $75 |  | $64 |  | $48 |  | $43 |  | $27 |  | $21
Derivative liabilities | 58 |  | 47 |  | 13 |  | 8 |  | 45 |  | 39
2023 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 88 |  | 47 |  | 54 |  | 32 |  | 34 |  | 15
Derivative liabilities | 98 |  | 57 |  | 30 |  | 8 |  | 68 |  | 49
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. Interest Rate Derivative - In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026 to mitigate interest rate risk. Under the terms of the swap, AEF exchanged a variable interest rate for a fixed interest rate of 3.93% on a portion of its variable-rate term loan borrowings. The related interest rate derivative was valued based on quoted prices that utilize current market interest rate forecasts. As of both December 31, 2024 and 2023, $1 million of non-current interest rate derivative assets was recorded in “Deferred charges and other” on Alliant Energy’s balance sheets. This interest rate derivative was designated as a cash flow hedge, with changes in fair value recorded as other comprehensive income/loss. As of both December 31, 2024 and 2023, accumulated other comprehensive income included $1 million of income related to the interest rate swap. In 2024 and 2023, $4 million and $3 million, respectively, of reductions to interest expense were recorded in Alliant Energy’s income statement related to the interest rate swap.
WPL [Member] |
Derivative [Line Items] |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Purpose - Derivative instruments were utilized for risk management purposes to mitigate pricing volatility for fuel used to supply natural gas-fired EGUs, natural gas supplied to retail customers, and purchased electricity, as well as optimize the value of natural gas pipeline capacity and electric generation, which may include swap, physical forward and option contracts. In addition, FTRs help manage transmission congestion costs in the MISO market. Risk policies are maintained that govern the use of such derivative instruments. Notional Amounts - As of December 31, 2024, 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):
| Electricity |  | FTRs |  | Natural Gas |  |  |  | Diesel Fuel
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  | Gallons |  | Years
Alliant Energy | 1,422 |  |  | 2025-2026 |  | 10,232 |  |  | 2025 |  | 147,894 |  |  | 2025-2032 |  |  |  |  |  | 2,520 |  |  | 2025
IPL | 383 |  |  | 2025-2026 |  | 3,551 |  |  | 2025 |  | 61,489 |  |  | 2025-2030 |  |  |  |  |  | — |  |  | —
WPL | 1,039 |  |  | 2025-2026 |  | 6,681 |  |  | 2025 |  | 86,405 |  |  | 2025-2032 |  |  |  |  |  | 2,520 |  |  | 2025
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
| 2024 |  | 2023 |  | 2024 |  | 2023 |  | 2024 |  | 2023
Current derivative assets | $41 |  | $44 |  | $29 |  | $30 |  | $12 |  | $14
Non-current derivative assets | 34 |  | 44 |  | 19 |  | 24 |  | 15 |  | 20
Current derivative liabilities | 26 |  | 51 |  | 11 |  | 22 |  | 15 |  | 29
Non-current derivative liabilities | 32 |  | 47 |  | 2 |  | 8 |  | 30 |  | 39
In 2024, Alliant Energy’s, IPL’s and WPL’s derivative liabilities decreased primarily due to settlements of natural gas contracts and higher natural gas prices. Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets. 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 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, 2024 and 2023, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different th an 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, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets at December 31 as follows:
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
2024 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $75 |  | $64 |  | $48 |  | $43 |  | $27 |  | $21
Derivative liabilities | 58 |  | 47 |  | 13 |  | 8 |  | 45 |  | 39
2023 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 88 |  | 47 |  | 54 |  | 32 |  | 34 |  | 15
Derivative liabilities | 98 |  | 57 |  | 30 |  | 8 |  | 68 |  | 49
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. Interest Rate Derivative - In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026 to mitigate interest rate risk. Under the terms of the swap, AEF exchanged a variable interest rate for a fixed interest rate of 3.93% on a portion of its variable-rate term loan borrowings. The related interest rate derivative was valued based on quoted prices that utilize current market interest rate forecasts. As of both December 31, 2024 and 2023, $1 million of non-current interest rate derivative assets was recorded in “Deferred charges and other” on Alliant Energy’s balance sheets. This interest rate derivative was designated as a cash flow hedge, with changes in fair value recorded as other comprehensive income/loss. As of both December 31, 2024 and 2023, accumulated other comprehensive income included $1 million of income related to the interest rate swap. In 2024 and 2023, $4 million and $3 million, respectively, of reductions to interest expense were recorded in Alliant Energy’s income statement related to the interest rate swap.

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