Income Taxes (Tables)

3 Months Ended

Mar. 31, 2022

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three months ended March 31, 2022 compared to the same period in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL.

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Overall income tax rate	4%	(19%)	(14%)	(17%)	19%	(29%)

Summary Of Tax Credit Carryforwards

At March 31, 2022, carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
Federal net operating losses	2037	$94	$87	$1
State net operating losses	2022-2042	578	13	2
Federal tax credits	2022-2042	589	369	197

IPL [Member]

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three months ended March 31, 2022 compared to the same period in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL.

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Overall income tax rate	4%	(19%)	(14%)	(17%)	19%	(29%)

Summary Of Tax Credit Carryforwards

At March 31, 2022, carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
Federal net operating losses	2037	$94	$87	$1
State net operating losses	2022-2042	578	13	2
Federal tax credits	2022-2042	589	369	197

WPL [Member]

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

Overall effective income tax rates, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. The increases in Alliant Energy’s and WPL’s overall effective income tax rates for the three months ended March 31, 2022 compared to the same period in 2021 were primarily due to decreased amortization of excess deferred taxes primarily at WPL.

	Alliant Energy		IPL		WPL
	2022	2021	2022	2021	2022	2021
Overall income tax rate	4%	(19%)	(14%)	(17%)	19%	(29%)

Summary Of Tax Credit Carryforwards

At March 31, 2022, carryforwards and expiration dates were estimated as follows (in millions):

	Range of Expiration Dates	Alliant Energy	IPL	WPL
Federal net operating losses	2037	$94	$87	$1
State net operating losses	2022-2042	578	13	2
Federal tax credits	2022-2042	589	369	197