INCOME TAXES

Our effective tax rate is impacted primarily by the amount of taxable income associated with each jurisdiction in which our income is subject to income tax, permanent differences between the financial statement carrying amounts and tax bases of assets and liabilities.

A summary of the provision for income taxes is as follows (in thousands):



	Three Months Ended March 31,
	2015			2014
Current portion of income tax expense (benefit)	$	114		$	—
Deferred portion of income tax expense (benefit)	2,957			(2,778		)
Total income tax expense (benefit)	$	3,071		$	(2,778	)
Effective tax rate	32.0		%	(88.7		)%

During the three months ended March 31, 2015, our effective tax rate differed from the statutory rate primarily as a result of the benefit from estimated depletion deductions. During the three months ended March 31, 2014, in addition to the items noted above, we also benefited from a discrete adjustment related to the reversal of a $1.7 million valuation allowance related to our New Mexico net operating loss carry forwards, as those carry forwards became realizable based on legislation passed by the State of New Mexico in the first quarter of 2014.

The blended state tax rate applied to the deferred tax calculation is subject to change due to changes in state laws and changes in the mix of our business and the states in which we have a taxable relationship. This creates fluctuations in the value of our net deferred tax asset.