Income Taxes (Tables)

6 Months Ended

Jun. 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 June 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	)	(11.9	)	(25.3	)	(36.6	)	—		—
Effect of rate-making on property-related differences	(8.4	)	(4.8	)	(22.3	)	(14.4	)	(0.7	)	(0.2	)
Production tax credits	(6.5	)	(6.1	)	(7.2	)	(8.0	)	(6.7	)	(5.8	)
Other items, net	4.1		4.8		4.1		4.6		4.6		5.0
Overall income tax rate	13.6	%	17.0	%	(15.7	%)	(19.4	%)	32.2	%	34.0	%

	Alliant Energy				IPL				WPL
Six Months Ended June 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	(10.2	)	(11.9	)	(25.2	)	(32.8	)	—		—
Effect of rate-making on property-related differences	(7.0	)	(5.1	)	(16.6	)	(13.0	)	(0.6	)	(0.7	)
Production tax credits	(6.4	)	(6.5	)	(7.2	)	(8.2	)	(6.4	)	(6.2	)
Other items, net	4.3		4.7		4.2		4.6		4.7		4.9
Overall income tax rate	15.7	%	16.2	%	(9.8	%)	(14.4	%)	32.7	%	33.0	%

Summary Of Tax Credit Carryforwards

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

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$845		$290	2029
State net operating losses	860		44		2018
Federal tax credits	222		218		2022
				$552

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$396		$136	2029
State net operating losses	265		14		2018
Federal tax credits	77		75		2022
				$225

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$342		$117	2029
State net operating losses	170		8		2018
Federal tax credits	86		85		2022
				$210

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 June 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	)	(11.9	)	(25.3	)	(36.6	)	—		—
Effect of rate-making on property-related differences	(8.4	)	(4.8	)	(22.3	)	(14.4	)	(0.7	)	(0.2	)
Production tax credits	(6.5	)	(6.1	)	(7.2	)	(8.0	)	(6.7	)	(5.8	)
Other items, net	4.1		4.8		4.1		4.6		4.6		5.0
Overall income tax rate	13.6	%	17.0	%	(15.7	%)	(19.4	%)	32.2	%	34.0	%

	Alliant Energy				IPL				WPL
Six Months Ended June 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	(10.2	)	(11.9	)	(25.2	)	(32.8	)	—		—
Effect of rate-making on property-related differences	(7.0	)	(5.1	)	(16.6	)	(13.0	)	(0.6	)	(0.7	)
Production tax credits	(6.4	)	(6.5	)	(7.2	)	(8.2	)	(6.4	)	(6.2	)
Other items, net	4.3		4.7		4.2		4.6		4.7		4.9
Overall income tax rate	15.7	%	16.2	%	(9.8	%)	(14.4	%)	32.7	%	33.0	%

Summary Of Tax Credit Carryforwards

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

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$845		$290	2029
State net operating losses	860		44		2018
Federal tax credits	222		218		2022
				$552

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$396		$136	2029
State net operating losses	265		14		2018
Federal tax credits	77		75		2022
				$225

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$342		$117	2029
State net operating losses	170		8		2018
Federal tax credits	86		85		2022
				$210

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 June 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	)	(11.9	)	(25.3	)	(36.6	)	—		—
Effect of rate-making on property-related differences	(8.4	)	(4.8	)	(22.3	)	(14.4	)	(0.7	)	(0.2	)
Production tax credits	(6.5	)	(6.1	)	(7.2	)	(8.0	)	(6.7	)	(5.8	)
Other items, net	4.1		4.8		4.1		4.6		4.6		5.0
Overall income tax rate	13.6	%	17.0	%	(15.7	%)	(19.4	%)	32.2	%	34.0	%

	Alliant Energy				IPL				WPL
Six Months Ended June 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	(10.2	)	(11.9	)	(25.2	)	(32.8	)	—		—
Effect of rate-making on property-related differences	(7.0	)	(5.1	)	(16.6	)	(13.0	)	(0.6	)	(0.7	)
Production tax credits	(6.4	)	(6.5	)	(7.2	)	(8.2	)	(6.4	)	(6.2	)
Other items, net	4.3		4.7		4.2		4.6		4.7		4.9
Overall income tax rate	15.7	%	16.2	%	(9.8	%)	(14.4	%)	32.7	%	33.0	%

Summary Of Tax Credit Carryforwards

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

Alliant Energy	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$845		$290	2029
State net operating losses	860		44		2018
Federal tax credits	222		218		2022
				$552

IPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$396		$136	2029
State net operating losses	265		14		2018
Federal tax credits	77		75		2022
				$225

WPL	Tax Carryforwards		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$342		$117	2029
State net operating losses	170		8		2018
Federal tax credits	86		85		2022
				$210