Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2025

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024
Tax-related	$1,069	$989	$932	$870	$137	$119
AROs	441	401	304	281	137	120
Pension and OPEB costs	301	315	151	157	150	158
Assets retired early	162	180	153	168	9	12
Non-service pension and OPEB costs	55	51	20	19	35	32
Derivatives	51	60	12	15	39	45
WPL’s Western Wisconsin gas distribution expansion investments	40	42	—	—	40	42
Commodity cost recovery	33	68	8	2	25	66
Other	151	168	52	74	99	94
	$2,303	$2,274	$1,632	$1,586	$671	$688

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024
Tax-related	$658	$582	$301	$286	$357	$296
Cost of removal obligations	351	347	206	205	145	142
Derivatives	49	53	25	29	24	24
Other	76	46	26	26	50	20
	$1,134	$1,028	$558	$546	$576	$482

IPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024
Tax-related	$1,069	$989	$932	$870	$137	$119
AROs	441	401	304	281	137	120
Pension and OPEB costs	301	315	151	157	150	158
Assets retired early	162	180	153	168	9	12
Non-service pension and OPEB costs	55	51	20	19	35	32
Derivatives	51	60	12	15	39	45
WPL’s Western Wisconsin gas distribution expansion investments	40	42	—	—	40	42
Commodity cost recovery	33	68	8	2	25	66
Other	151	168	52	74	99	94
	$2,303	$2,274	$1,632	$1,586	$671	$688

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024
Tax-related	$658	$582	$301	$286	$357	$296
Cost of removal obligations	351	347	206	205	145	142
Derivatives	49	53	25	29	24	24
Other	76	46	26	26	50	20
	$1,134	$1,028	$558	$546	$576	$482

WPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024
Tax-related	$1,069	$989	$932	$870	$137	$119
AROs	441	401	304	281	137	120
Pension and OPEB costs	301	315	151	157	150	158
Assets retired early	162	180	153	168	9	12
Non-service pension and OPEB costs	55	51	20	19	35	32
Derivatives	51	60	12	15	39	45
WPL’s Western Wisconsin gas distribution expansion investments	40	42	—	—	40	42
Commodity cost recovery	33	68	8	2	25	66
Other	151	168	52	74	99	94
	$2,303	$2,274	$1,632	$1,586	$671	$688

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

	Alliant Energy		IPL		WPL
	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024	September 30, 2025	December 31, 2024
Tax-related	$658	$582	$301	$286	$357	$296
Cost of removal obligations	351	347	206	205	145	142
Derivatives	49	53	25	29	24	24
Other	76	46	26	26	50	20
	$1,134	$1,028	$558	$546	$576	$482