Income Taxes (Tables)

9 Months Ended

Sep. 30, 2020

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The following table reconciles the difference between the statutory rate and the ETR:

	Nine Months Ended Sept. 30
	2020		2019
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	6.2		6.2
Increases (decreases) in tax from:
Plant regulatory differences (a)	(19.6)		(0.4)
Nonplant ADIT amortization	(12.8)		—
Tax credits, net of NOL & tax credit allowances	(1.6)		(1.5)
Prior period adjustments	0.5		0.4
Other (net)	(0.6)		0.7
Effective income tax rate	(6.9)	%	26.4	%

(a)     Regulatory differences for income tax primarily relates to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit of excess deferred credits are offset by corresponding revenue reductions.

Summary of Statute of Limitations Applicable to Open Tax Years [Table Text Block]

Federal Audits — NSP-Wisconsin is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. Statute of limitations applicable to Xcel Energy’s consolidated federal income tax returns expire as follows:

Tax Years	Expiration
2014 - 2016	July 2021

Reconciliation of Unrecognized Tax Benefits

Unrecognized tax benefits — permanent vs. temporary:

(Millions of Dollars)	Sept. 30, 2020		Dec. 31, 2019
Unrecognized tax benefit — Permanent tax positions	$	1.6	$	2.6
Unrecognized tax benefit — Temporary tax positions	—		0.8
Total unrecognized tax benefit	$	1.6	$	3.4

Tax Benefits Associated with NOL and Tax Credit Carryforwards

Unrecognized tax benefits were reduced by tax benefits associated with NOL and tax credit carryforwards:

(Millions of Dollars)	Sept. 30, 2020		Dec. 31, 2019
NOL and tax credit carryforwards	$	(1.2)	$	(2.2)