Segments Of Business (Tables)

6 Months Ended

Jun. 30, 2025

Segment Reporting Information [Line Items]

Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s reportable segments, which represents the services provided to their customers, and reconciliation to consolidated amounts, was as follows (in millions):


	Utility
			Total		Alliant
			Reportable		Energy
Three Months Ended June 30, 2025	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$418	$433	$851	N/A	$851
Gas utility revenues	40	36	76	N/A	76
Other revenues	11	—	11	$23	34
Total revenues	469	469	938	23	961
Electric production fuel and purchased power expense	40	110	150	N/A	150
Electric transmission service expense	100	51	151	N/A	151
Cost of gas sold expense	17	13	30	N/A	30

Other operation and maintenance expense	84	72	156	12	168
Other segment items:
Depreciation and amortization expense	115	90	205	3	208
Interest expense	52	43	95	29	124
Equity income from unconsolidated investments, net	—	(1)	(1)	(9)	(10)
Income tax benefit	(37)	(5)	(42)	(1)	(43)
Other (a)	—	9	9	—	9
Net income (loss)	98	87	185	(11)	174
Total assets (as of June 30, 2025)	12,180	10,236	22,416	1,334	23,750
Investments in equity method subsidiaries (as of June 30, 2025)	5	18	23	622	645
Construction and acquisition expenditures	252	170	422	61	483


	Utility
			Total		Alliant
Three Months Ended June 30, 2024 (amounts may not foot due to rounding)			Reportable		Energy
	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$404	$385	$789	N/A	$789
Gas utility revenues	40	29	69	N/A	69
Other revenues	9	1	10	$26	36
Total revenues	453	415	868	26	894
Electric production fuel and purchased power expense	48	90	138	N/A	138
Electric transmission service expense	99	49	148	N/A	147
Cost of gas sold expense	17	8	25	N/A	25
Asset valuation charge for IPL’s Lansing Generating Station	60	—	60	N/A	60
Other operation and maintenance expense	102	67	169	8	177
Other segment items:
Depreciation and amortization expense	97	87	184	4	188
Interest expense	42	41	83	25	108
Equity income from unconsolidated investments, net	—	(1)	(1)	(14)	(15)
Income tax expense (benefit)	(33)	3	(30)	(3)	(33)
Other (a)	3	7	10	1	12
Net income	18	64	82	5	87
Total assets (as of June 30, 2024)	10,732	9,925	20,657	1,179	21,836
Investments in equity method subsidiaries (as of June 30, 2024)	5	17	22	584	606
Construction and acquisition expenditures	247	145	392	58	450



	Utility
			Total		Alliant
			Reportable		Energy
Six Months Ended June 30, 2025	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$848	$855	$1,703	N/A	$1,703
Gas utility revenues	158	158	316	N/A	316
Other revenues	24	1	25	$44	69
Total revenues	1,030	1,014	2,044	44	2,088
Electric production fuel and purchased power expense	107	218	325	N/A	325
Electric transmission service expense	207	101	308	N/A	308
Cost of gas sold expense	81	86	167	N/A	167

Other operation and maintenance expense	169	137	306	21	327
Other segment items:
Depreciation and amortization expense	230	183	413	7	420
Interest expense	99	86	185	58	243
Equity income from unconsolidated investments, net	—	(1)	(1)	(22)	(23)
Income tax benefit	(77)	(10)	(87)	(4)	(91)
Other (a)	5	16	21	4	25
Net income (loss)	209	198	407	(20)	387


Construction and acquisition expenditures	628	348	976	89	1,065



	Utility
			Total		Alliant
Six Months Ended June 30, 2024 (amounts may not foot due to rounding)			Reportable		Energy
	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$795	$785	$1,580	N/A	$1,580
Gas utility revenues	148	125	273	N/A	273
Other revenues	23	1	24	$48	72
Total revenues	966	911	1,877	48	1,925
Electric production fuel and purchased power expense	116	186	302	N/A	301
Electric transmission service expense	202	98	300	N/A	300
Cost of gas sold expense	77	62	139	N/A	139
Asset valuation charge for IPL’s Lansing Generating Station	60	—	60	N/A	60
Other operation and maintenance expense	187	128	315	21	336
Other segment items:
Depreciation and amortization expense	193	178	371	5	376
Interest expense	84	82	166	49	215
Equity income from unconsolidated investments, net	—	(1)	(1)	(30)	(31)
Income tax expense (benefit)	(43)	8	(35)	(8)	(43)
Other (a)	9	14	23	3	27
Net income	81	156	237	8	245


Construction and acquisition expenditures	500	370	870	90	960

(a)Other segment items for each reportable segment include allowance for funds used during construction, taxes other than income taxes, interest income, and other miscellaneous income and deductions.

IPL [Member]

Segment Reporting Information [Line Items]

Schedule Of Segments Of Business


	Utility
			Total		Alliant
			Reportable		Energy
Three Months Ended June 30, 2025	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$418	$433	$851	N/A	$851
Gas utility revenues	40	36	76	N/A	76
Other revenues	11	—	11	$23	34
Total revenues	469	469	938	23	961
Electric production fuel and purchased power expense	40	110	150	N/A	150
Electric transmission service expense	100	51	151	N/A	151
Cost of gas sold expense	17	13	30	N/A	30

Other operation and maintenance expense	84	72	156	12	168
Other segment items:
Depreciation and amortization expense	115	90	205	3	208
Interest expense	52	43	95	29	124
Equity income from unconsolidated investments, net	—	(1)	(1)	(9)	(10)
Income tax benefit	(37)	(5)	(42)	(1)	(43)
Other (a)	—	9	9	—	9
Net income (loss)	98	87	185	(11)	174
Total assets (as of June 30, 2025)	12,180	10,236	22,416	1,334	23,750
Investments in equity method subsidiaries (as of June 30, 2025)	5	18	23	622	645
Construction and acquisition expenditures	252	170	422	61	483


	Utility
			Total		Alliant
Three Months Ended June 30, 2024 (amounts may not foot due to rounding)			Reportable		Energy
	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$404	$385	$789	N/A	$789
Gas utility revenues	40	29	69	N/A	69
Other revenues	9	1	10	$26	36
Total revenues	453	415	868	26	894
Electric production fuel and purchased power expense	48	90	138	N/A	138
Electric transmission service expense	99	49	148	N/A	147
Cost of gas sold expense	17	8	25	N/A	25
Asset valuation charge for IPL’s Lansing Generating Station	60	—	60	N/A	60
Other operation and maintenance expense	102	67	169	8	177
Other segment items:
Depreciation and amortization expense	97	87	184	4	188
Interest expense	42	41	83	25	108
Equity income from unconsolidated investments, net	—	(1)	(1)	(14)	(15)
Income tax expense (benefit)	(33)	3	(30)	(3)	(33)
Other (a)	3	7	10	1	12
Net income	18	64	82	5	87
Total assets (as of June 30, 2024)	10,732	9,925	20,657	1,179	21,836
Investments in equity method subsidiaries (as of June 30, 2024)	5	17	22	584	606
Construction and acquisition expenditures	247	145	392	58	450



	Utility
			Total		Alliant
			Reportable		Energy
Six Months Ended June 30, 2025	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$848	$855	$1,703	N/A	$1,703
Gas utility revenues	158	158	316	N/A	316
Other revenues	24	1	25	$44	69
Total revenues	1,030	1,014	2,044	44	2,088
Electric production fuel and purchased power expense	107	218	325	N/A	325
Electric transmission service expense	207	101	308	N/A	308
Cost of gas sold expense	81	86	167	N/A	167

Other operation and maintenance expense	169	137	306	21	327
Other segment items:
Depreciation and amortization expense	230	183	413	7	420
Interest expense	99	86	185	58	243
Equity income from unconsolidated investments, net	—	(1)	(1)	(22)	(23)
Income tax benefit	(77)	(10)	(87)	(4)	(91)
Other (a)	5	16	21	4	25
Net income (loss)	209	198	407	(20)	387


Construction and acquisition expenditures	628	348	976	89	1,065



	Utility
			Total		Alliant
Six Months Ended June 30, 2024 (amounts may not foot due to rounding)			Reportable		Energy
	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$795	$785	$1,580	N/A	$1,580
Gas utility revenues	148	125	273	N/A	273
Other revenues	23	1	24	$48	72
Total revenues	966	911	1,877	48	1,925
Electric production fuel and purchased power expense	116	186	302	N/A	301
Electric transmission service expense	202	98	300	N/A	300
Cost of gas sold expense	77	62	139	N/A	139
Asset valuation charge for IPL’s Lansing Generating Station	60	—	60	N/A	60
Other operation and maintenance expense	187	128	315	21	336
Other segment items:
Depreciation and amortization expense	193	178	371	5	376
Interest expense	84	82	166	49	215
Equity income from unconsolidated investments, net	—	(1)	(1)	(30)	(31)
Income tax expense (benefit)	(43)	8	(35)	(8)	(43)
Other (a)	9	14	23	3	27
Net income	81	156	237	8	245


Construction and acquisition expenditures	500	370	870	90	960

(a)Other segment items for each reportable segment include allowance for funds used during construction, taxes other than income taxes, interest income, and other miscellaneous income and deductions.

WPL [Member]

Segment Reporting Information [Line Items]

Schedule Of Segments Of Business


	Utility
			Total		Alliant
			Reportable		Energy
Three Months Ended June 30, 2025	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$418	$433	$851	N/A	$851
Gas utility revenues	40	36	76	N/A	76
Other revenues	11	—	11	$23	34
Total revenues	469	469	938	23	961
Electric production fuel and purchased power expense	40	110	150	N/A	150
Electric transmission service expense	100	51	151	N/A	151
Cost of gas sold expense	17	13	30	N/A	30

Other operation and maintenance expense	84	72	156	12	168
Other segment items:
Depreciation and amortization expense	115	90	205	3	208
Interest expense	52	43	95	29	124
Equity income from unconsolidated investments, net	—	(1)	(1)	(9)	(10)
Income tax benefit	(37)	(5)	(42)	(1)	(43)
Other (a)	—	9	9	—	9
Net income (loss)	98	87	185	(11)	174
Total assets (as of June 30, 2025)	12,180	10,236	22,416	1,334	23,750
Investments in equity method subsidiaries (as of June 30, 2025)	5	18	23	622	645
Construction and acquisition expenditures	252	170	422	61	483


	Utility
			Total		Alliant
Three Months Ended June 30, 2024 (amounts may not foot due to rounding)			Reportable		Energy
	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$404	$385	$789	N/A	$789
Gas utility revenues	40	29	69	N/A	69
Other revenues	9	1	10	$26	36
Total revenues	453	415	868	26	894
Electric production fuel and purchased power expense	48	90	138	N/A	138
Electric transmission service expense	99	49	148	N/A	147
Cost of gas sold expense	17	8	25	N/A	25
Asset valuation charge for IPL’s Lansing Generating Station	60	—	60	N/A	60
Other operation and maintenance expense	102	67	169	8	177
Other segment items:
Depreciation and amortization expense	97	87	184	4	188
Interest expense	42	41	83	25	108
Equity income from unconsolidated investments, net	—	(1)	(1)	(14)	(15)
Income tax expense (benefit)	(33)	3	(30)	(3)	(33)
Other (a)	3	7	10	1	12
Net income	18	64	82	5	87
Total assets (as of June 30, 2024)	10,732	9,925	20,657	1,179	21,836
Investments in equity method subsidiaries (as of June 30, 2024)	5	17	22	584	606
Construction and acquisition expenditures	247	145	392	58	450



	Utility
			Total		Alliant
			Reportable		Energy
Six Months Ended June 30, 2025	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$848	$855	$1,703	N/A	$1,703
Gas utility revenues	158	158	316	N/A	316
Other revenues	24	1	25	$44	69
Total revenues	1,030	1,014	2,044	44	2,088
Electric production fuel and purchased power expense	107	218	325	N/A	325
Electric transmission service expense	207	101	308	N/A	308
Cost of gas sold expense	81	86	167	N/A	167

Other operation and maintenance expense	169	137	306	21	327
Other segment items:
Depreciation and amortization expense	230	183	413	7	420
Interest expense	99	86	185	58	243
Equity income from unconsolidated investments, net	—	(1)	(1)	(22)	(23)
Income tax benefit	(77)	(10)	(87)	(4)	(91)
Other (a)	5	16	21	4	25
Net income (loss)	209	198	407	(20)	387


Construction and acquisition expenditures	628	348	976	89	1,065



	Utility
			Total		Alliant
Six Months Ended June 30, 2024 (amounts may not foot due to rounding)			Reportable		Energy
	IPL	WPL	Segments	Other	Consolidated
Electric utility revenues	$795	$785	$1,580	N/A	$1,580
Gas utility revenues	148	125	273	N/A	273
Other revenues	23	1	24	$48	72
Total revenues	966	911	1,877	48	1,925
Electric production fuel and purchased power expense	116	186	302	N/A	301
Electric transmission service expense	202	98	300	N/A	300
Cost of gas sold expense	77	62	139	N/A	139
Asset valuation charge for IPL’s Lansing Generating Station	60	—	60	N/A	60
Other operation and maintenance expense	187	128	315	21	336
Other segment items:
Depreciation and amortization expense	193	178	371	5	376
Interest expense	84	82	166	49	215
Equity income from unconsolidated investments, net	—	(1)	(1)	(30)	(31)
Income tax expense (benefit)	(43)	8	(35)	(8)	(43)
Other (a)	9	14	23	3	27
Net income	81	156	237	8	245


Construction and acquisition expenditures	500	370	870	90	960

(a)Other segment items for each reportable segment include allowance for funds used during construction, taxes other than income taxes, interest income, and other miscellaneous income and deductions.