Except to the extent noted below, Note 7 to the financial statements included in SPS’ Annual Report on Form 10-K for the year ended Dec. 31, 2018 represents, in all material respects, the current status of other income tax matters, and are incorporated herein by reference.



	Six Months Ended June 30,
	2019		2018
Federal statutory rate	21.0	%	21.0	%
State tax (net of federal tax effect)	2.1		2.4
Increases (decreases) in tax from:
Plant regulatory differences ^(a)	(4.8	)	(4.4	)
Prior period adjustments	(0.7	)	(0.2	)
Other tax credits (net)	(0.6	)	(0.8	)
Wind PTCs	(0.2	)	—
Other (net)	(0.4	)	0.4
Effective income tax rate	16.4	%	18.4	%

Federal Audits — SPS 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 federal income tax returns expire as follows:

In 2015, the IRS commenced an examination of tax years 2012 and 2013. In 2017, the IRS concluded the audit of tax years 2012 and 2013 and proposed an adjustment that would impact Xcel Energy’s NOL and ETR. Xcel Energy filed a protest with the IRS. As of June 30, 2019, the case has been forwarded to the Office of Appeals and Xcel Energy has recognized its best estimate of income tax expense that will result from a final resolution of this issue; however, the outcome and timing of a resolution is unknown.

In 2018, the IRS began an audit of tax years 2014 - 2016. As of June 30, 2019 no adjustments have been proposed.

State Audits — SPS is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of June 30, 2019, SPS’ earliest open tax year that is subject to examination by state taxing authorities under applicable statutes of limitations is 2009. There are currently no state income tax audits in progress.

Unrecognized Benefits — Unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which the ultimate deductibility is highly certain, but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the ETR but would accelerate the payment to the taxing authority to an earlier period.



(Millions of Dollars)	June 30, 2019		Dec. 31, 2018
Unrecognized tax benefit — Permanent tax positions	$	3.3	$	3.0
Unrecognized tax benefit — Temporary tax positions	1.5		1.5
Total unrecognized tax benefit	$	4.8	$	4.5

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



(Millions of Dollars)	June 30, 2019			Dec. 31, 2018
NOL and tax credit carryforwards	$	(4.1	)	$	(3.8	)

Net deferred tax liability associated with the unrecognized tax benefit amounts and related NOLs and tax credits carryforwards were $1.1 million and $0.8 million at June 30, 2019 and Dec. 31, 2018, respectively.

As the IRS Appeals and federal audit progress, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $3.6 million in the next 12 months.

Payables for interest related to unrecognized tax benefits were not material and no amounts were accrued for penalties related to unrecognized tax benefits as of June 30, 2019 or Dec. 31, 2018.