Income Taxes

6 Months Ended

Jun. 30, 2019

Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]

Income Taxes

Income Taxes

The Company files income tax returns in the U.S. federal jurisdiction and in the states of Texas, New Mexico and Arizona. The Company is no longer subject to tax examination by the taxing authorities in the federal, Texas, Arizona, and New Mexico jurisdictions for years prior to 2014.

For the three months ended June 30, 2019 and 2018, the Company’s effective tax rate was 21.8% and 24.4%, respectively. For the six months ended June 30, 2019 and 2018, the Company's effective tax rate was 22.2% and 22.7%, respectively. For the twelve months ended June 30, 2019 and 2018, the Company's effective tax rate was 23.6% and 30.8%, respectively. The federal statutory tax rate is 21% in 2019 and 2018, and 35% in 2017. The Company's effective tax rate for all periods in 2019 and 2018 differ from the federal statutory tax rate due to state income taxes, capital gains in the decommissioning trusts which are taxed at the federal rate of 20%, the tax benefit of stock incentive plans, the allowance for equity funds used during construction ("AEFUDC") and other permanent differences.