Debt

3 Months Ended

Mar. 31, 2025

Debt [Line Items]

Debt

DEBT

NOTE 6(a) Short-term Debt - In March 2025, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $550 million for Alliant Energy at the parent company level, $350 million for IPL and $400 million for WPL, within the $1.3 billion total commitment. Information regarding commercial paper classified as short-term debt was as follows (dollars in millions):

March 31, 2025	Alliant Energy	IPL	WPL
Amount outstanding	$678	$109	$212
Weighted average interest rates	4.6%	4.6%	4.6%
Available credit facility capacity (a)	$522	$141	$188

	Alliant Energy		IPL		WPL
Three Months Ended March 31	2025	2024	2025	2024	2025	2024
Maximum amount outstanding (based on daily outstanding balances)	$678	$632	$127	$14	$224	$390
Average amount outstanding (based on daily outstanding balances)	$541	$487	$53	$1	$159	$255
Weighted average interest rates	4.5%	5.5%	4.6%	5.5%	4.5%	5.5%

(a)Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at March 31, 2025.

NOTE 6(b) Long-term Debt - In March 2025, AEF entered into a $300 million variable rate (5% as of March 31, 2025) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2026. This term loan credit agreement amended and restated the term loan credit agreement that expired in March 2025, and retired the $300 million variable rate term loan set forth therein. AEF’s restated term loan credit agreement includes an option to increase the amount outstanding with one or more additional term loans in an aggregate amount not to exceed $100 million.

As of March 31, 2025, $100 million of commercial paper was recorded in “Long-term debt, net” on Alliant Energy’s and IPL’s balance sheets due to the existence of the long-term single credit facility that back-stops this commercial paper balance, along with Alliant Energy’s and IPL’s intent and ability to refinance these balances on a long-term basis. As of March 31, 2025, this commercial paper balance had a 4.6% interest rate. In the second quarter of 2025, Alliant Energy’s and IPL’s commercial paper classified as long-term debt increased $50 million.

Convertible Senior Notes - As of March 31, 2025, the conditions allowing holders of Alliant Energy’s convertible senior notes due 2026 (the Notes) to convert their Notes were not met, and the Notes were classified as “Current maturities of long-term debt” on Alliant Energy’s balance sheet. As of March 31, 2025, the net carrying amount of the Notes was $572 million, with unamortized debt issuance costs of $3 million, and the estimated fair value (Level 2) of the Notes was $617 million. As of March 31, 2025, there were no shares of Alliant Energy’s common stock related to the potential conversion of the Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the Notes.

IPL [Member]

Debt [Line Items]

Debt

DEBT

NOTE 6(a) Short-term Debt - In March 2025, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $550 million for Alliant Energy at the parent company level, $350 million for IPL and $400 million for WPL, within the $1.3 billion total commitment. Information regarding commercial paper classified as short-term debt was as follows (dollars in millions):

March 31, 2025	Alliant Energy	IPL	WPL
Amount outstanding	$678	$109	$212
Weighted average interest rates	4.6%	4.6%	4.6%
Available credit facility capacity (a)	$522	$141	$188

	Alliant Energy		IPL		WPL
Three Months Ended March 31	2025	2024	2025	2024	2025	2024
Maximum amount outstanding (based on daily outstanding balances)	$678	$632	$127	$14	$224	$390
Average amount outstanding (based on daily outstanding balances)	$541	$487	$53	$1	$159	$255
Weighted average interest rates	4.5%	5.5%	4.6%	5.5%	4.5%	5.5%

(a)Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at March 31, 2025.

NOTE 6(b) Long-term Debt - In March 2025, AEF entered into a $300 million variable rate (5% as of March 31, 2025) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2026. This term loan credit agreement amended and restated the term loan credit agreement that expired in March 2025, and retired the $300 million variable rate term loan set forth therein. AEF’s restated term loan credit agreement includes an option to increase the amount outstanding with one or more additional term loans in an aggregate amount not to exceed $100 million.

As of March 31, 2025, $100 million of commercial paper was recorded in “Long-term debt, net” on Alliant Energy’s and IPL’s balance sheets due to the existence of the long-term single credit facility that back-stops this commercial paper balance, along with Alliant Energy’s and IPL’s intent and ability to refinance these balances on a long-term basis. As of March 31, 2025, this commercial paper balance had a 4.6% interest rate. In the second quarter of 2025, Alliant Energy’s and IPL’s commercial paper classified as long-term debt increased $50 million.

Convertible Senior Notes - As of March 31, 2025, the conditions allowing holders of Alliant Energy’s convertible senior notes due 2026 (the Notes) to convert their Notes were not met, and the Notes were classified as “Current maturities of long-term debt” on Alliant Energy’s balance sheet. As of March 31, 2025, the net carrying amount of the Notes was $572 million, with unamortized debt issuance costs of $3 million, and the estimated fair value (Level 2) of the Notes was $617 million. As of March 31, 2025, there were no shares of Alliant Energy’s common stock related to the potential conversion of the Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the Notes.

WPL [Member]

Debt [Line Items]

Debt

DEBT

NOTE 6(a) Short-term Debt - In March 2025, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $550 million for Alliant Energy at the parent company level, $350 million for IPL and $400 million for WPL, within the $1.3 billion total commitment. Information regarding commercial paper classified as short-term debt was as follows (dollars in millions):

March 31, 2025	Alliant Energy	IPL	WPL
Amount outstanding	$678	$109	$212
Weighted average interest rates	4.6%	4.6%	4.6%
Available credit facility capacity (a)	$522	$141	$188

	Alliant Energy		IPL		WPL
Three Months Ended March 31	2025	2024	2025	2024	2025	2024
Maximum amount outstanding (based on daily outstanding balances)	$678	$632	$127	$14	$224	$390
Average amount outstanding (based on daily outstanding balances)	$541	$487	$53	$1	$159	$255
Weighted average interest rates	4.5%	5.5%	4.6%	5.5%	4.5%	5.5%

(a)Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at March 31, 2025.

NOTE 6(b) Long-term Debt - In March 2025, AEF entered into a $300 million variable rate (5% as of March 31, 2025) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2026. This term loan credit agreement amended and restated the term loan credit agreement that expired in March 2025, and retired the $300 million variable rate term loan set forth therein. AEF’s restated term loan credit agreement includes an option to increase the amount outstanding with one or more additional term loans in an aggregate amount not to exceed $100 million.

As of March 31, 2025, $100 million of commercial paper was recorded in “Long-term debt, net” on Alliant Energy’s and IPL’s balance sheets due to the existence of the long-term single credit facility that back-stops this commercial paper balance, along with Alliant Energy’s and IPL’s intent and ability to refinance these balances on a long-term basis. As of March 31, 2025, this commercial paper balance had a 4.6% interest rate. In the second quarter of 2025, Alliant Energy’s and IPL’s commercial paper classified as long-term debt increased $50 million.

Convertible Senior Notes - As of March 31, 2025, the conditions allowing holders of Alliant Energy’s convertible senior notes due 2026 (the Notes) to convert their Notes were not met, and the Notes were classified as “Current maturities of long-term debt” on Alliant Energy’s balance sheet. As of March 31, 2025, the net carrying amount of the Notes was $572 million, with unamortized debt issuance costs of $3 million, and the estimated fair value (Level 2) of the Notes was $617 million. As of March 31, 2025, there were no shares of Alliant Energy’s common stock related to the potential conversion of the Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the Notes.