Income Taxes

The Company adjusts its effective tax rate each quarter to be consistent with the estimated annual effective tax rate. The Company also records the tax effect of unusual or infrequently occurring discrete items.

The provision for income taxes is shown below:



	Three Months Ended March 31
	2018			2017
Income tax (benefit) expense	$	(987	)	$	5

The operating income tax benefit decreased $0.7 million to $0.2 million for the three months ended March 31, 2018 as compared to the three months ended March 31, 2017 mostly due to a decrease in the corporate federal income tax rate from 35 percent to 21 percent, effective January 1, 2018. The non-operating income tax expense decreased $1.6 million to $0.8 million for the three months ended March 31, 2018, as compared to the three months ended March 31, 2017, mostly due to a $1.5 million unrealized loss on certain benefit plan investments and a decrease in the corporate federal income tax rate from 35 percent to 21 percent, effective January 1, 2018. The Company's 2018 effective tax rate, before discrete items, is estimated to be 23%.

For year ended December 31, 2017, the Company recorded a provisional re-measurement of its deferred tax balances (related mostly to timing differences for plant-related items) which was offset by a change from a net deferred income tax regulatory asset to a net regulatory liability. The Company is continuing to work with state regulators to finalize the ratepayer net refund of $108.0 million to ensure compliance with federal normalization rules.

The final transition impacts of the Tax Cuts and Jobs Act (TCJA) may differ from the recorded amounts, possibly materially, due to, among other things, regulatory decisions that could differ from the Company’s determination of how the impacts of the TCJA are allocated between customers and shareholders. In addition, while the Company was able to make reasonable estimates of the impact of the reduction in federal tax rate and the elimination of bonus depreciation due to the enactment of the TCJA; the Company has not completed analysis for areas of the TCJA around Internal Revenue Code Section 162(m), full expensing of fixed assets, and other asset related items of the TCJA. Changes in interpretations, guidance on legislative intent, and any changes in accounting standards for income taxes in response to the TCJA could impact the recorded amounts. The Company will finalize and record any adjustments related to the TCJA within the one year measurement period provided under Staff Accounting Bulletin No. 118. The balances relating to TCJA impact continue to be provisional as of March 31, 2018.

The Company had unrecognized tax benefits of approximately $11.3 million and $10.5 million as of March 31, 2018 and March 31, 2017, respectively. Included in the balance of unrecognized tax benefits as of March 31, 2018 and March 31, 2017 are approximately $2.1 million and $2.3 million, respectively, of tax benefits that, if recognized, would result in an adjustment to the Company’s effective tax rate. The Company does not expect its unrecognized tax benefits to change significantly within the next 12 months.