Income Taxes (Tables)

9 Months Ended

Sep. 30, 2015

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended September 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(11.0	)	(13.0	)	(30.0	)	(39.2	)	—		—
Effect of rate-making on property-related differences	(7.1	)	(8.6	)	(18.7	)	(22.4	)	(0.7	)	(0.8	)
Production tax credits	(6.7	)	(6.8	)	(8.7	)	(9.3	)	(6.0	)	(6.2	)
Other items, net	3.0		0.7		2.9		2.2		4.5		—
Overall income tax rate	13.2	%	7.3	%	(19.5	%)	(33.7	%)	32.8	%	28.0	%

	Alliant Energy				IPL				WPL
Nine Months Ended September 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.6	)	(12.4	)	(28.2	)	(36.5	)	—		—
Effect of rate-making on property-related differences	(7.1	)	(6.7	)	(17.9	)	(18.4	)	(0.6	)	(0.7	)
Production tax credits	(6.6	)	(6.6	)	(8.2	)	(8.8	)	(6.2	)	(6.2	)
Other items, net	3.7		2.9		3.5		3.2		4.5		3.0
Overall income tax rate	14.4	%	12.2	%	(15.8	%)	(25.5	%)	32.7	%	31.1	%

Summary Of Tax Credit Carryforwards

At September 30, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

		Alliant Energy				IPL				WPL
	Earliest Expiration Date	Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets
Federal net operating losses	2030		$527		$180		$231		$79		$218		$75
State net operating losses	2018	731		37		183		9		126		6
Federal tax credits	2022	227		224		80		78		89		87
					$441				$166				$168

IPL [Member]

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended September 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(11.0	)	(13.0	)	(30.0	)	(39.2	)	—		—
Effect of rate-making on property-related differences	(7.1	)	(8.6	)	(18.7	)	(22.4	)	(0.7	)	(0.8	)
Production tax credits	(6.7	)	(6.8	)	(8.7	)	(9.3	)	(6.0	)	(6.2	)
Other items, net	3.0		0.7		2.9		2.2		4.5		—
Overall income tax rate	13.2	%	7.3	%	(19.5	%)	(33.7	%)	32.8	%	28.0	%

	Alliant Energy				IPL				WPL
Nine Months Ended September 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.6	)	(12.4	)	(28.2	)	(36.5	)	—		—
Effect of rate-making on property-related differences	(7.1	)	(6.7	)	(17.9	)	(18.4	)	(0.6	)	(0.7	)
Production tax credits	(6.6	)	(6.6	)	(8.2	)	(8.8	)	(6.2	)	(6.2	)
Other items, net	3.7		2.9		3.5		3.2		4.5		3.0
Overall income tax rate	14.4	%	12.2	%	(15.8	%)	(25.5	%)	32.7	%	31.1	%

Summary Of Tax Credit Carryforwards

At September 30, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

		Alliant Energy				IPL				WPL
	Earliest Expiration Date	Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets
Federal net operating losses	2030		$527		$180		$231		$79		$218		$75
State net operating losses	2018	731		37		183		9		126		6
Federal tax credits	2022	227		224		80		78		89		87
					$441				$166				$168

WPL [Member]

Income Taxes [Line Items]

Schedule Of Effective Income Tax Rates

The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended September 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(11.0	)	(13.0	)	(30.0	)	(39.2	)	—		—
Effect of rate-making on property-related differences	(7.1	)	(8.6	)	(18.7	)	(22.4	)	(0.7	)	(0.8	)
Production tax credits	(6.7	)	(6.8	)	(8.7	)	(9.3	)	(6.0	)	(6.2	)
Other items, net	3.0		0.7		2.9		2.2		4.5		—
Overall income tax rate	13.2	%	7.3	%	(19.5	%)	(33.7	%)	32.8	%	28.0	%

	Alliant Energy				IPL				WPL
Nine Months Ended September 30	2015		2014		2015		2014		2015		2014
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(10.6	)	(12.4	)	(28.2	)	(36.5	)	—		—
Effect of rate-making on property-related differences	(7.1	)	(6.7	)	(17.9	)	(18.4	)	(0.6	)	(0.7	)
Production tax credits	(6.6	)	(6.6	)	(8.2	)	(8.8	)	(6.2	)	(6.2	)
Other items, net	3.7		2.9		3.5		3.2		4.5		3.0
Overall income tax rate	14.4	%	12.2	%	(15.8	%)	(25.5	%)	32.7	%	31.1	%

Summary Of Tax Credit Carryforwards

At September 30, 2015, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

		Alliant Energy				IPL				WPL
	Earliest Expiration Date	Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets		Tax Carryforwards		Deferred Tax Assets
Federal net operating losses	2030		$527		$180		$231		$79		$218		$75
State net operating losses	2018	731		37		183		9		126		6
Federal tax credits	2022	227		224		80		78		89		87
					$441				$166				$168