Income Taxes (Tables)

9 Months Ended

Sep. 30, 2019

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
	2019		2018
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	6.2		6.2
Increases (decreases) in tax from:
Tax credits and tax credit and NOL allowances (net)	(1.5	)	(0.7	)
Prior period adjustments	0.4		(0.6	)
Plant regulatory differences (a)	(0.4	)	(1.6	)
Other (net)	0.7		0.4
Effective income tax rate	26.4	%	24.7	%

^(a) Regulatory differences for income tax primarily relates to the credit of excess deferred taxes to customers through the average rate assumption method and the impact of AFUDC - equity. Year-to-date variations primarily relate to the impact of AFUDC - equity.

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 Year(s)	Expiration
2009 - 2013	June 2020
2014 - 2016	September 2020

Reconciliation of Unrecognized Tax Benefits

Unrecognized tax benefits — permanent vs. temporary:

(Millions of Dollars)	Sept. 30, 2019		Dec. 31, 2018
Unrecognized tax benefit — Permanent tax positions	$	2.5	$	2.0
Unrecognized tax benefit — Temporary tax positions	0.8		0.8
Total unrecognized tax benefit	$	3.3	$	2.8

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, 2019			Dec. 31, 2018
NOL and tax credit carryforwards	$	(2.5	)	$	(2.1	)