J. INCOME TAXES

The following table summarizes our effective tax rate and income tax expense (benefit) for the three months ended March 31, 2016 and 2015 (in thousands except for percentages):


	Three Months Ended March 31,
	2016			2015
Effective tax rate		25	%		30	%
Income tax expense (benefit)	$	(2,540)		$	5,608

For the three months ended March 31, 2016, we recognized an income tax benefit of $2.5 million, representing an effective tax rate of 25%. The difference between the expected statutory federal tax rate of 35% and the 25% effective tax rate for the three months ended March 31, 2016, was primarily attributable to the impact of state income taxes, stock compensation, and federal research and development and orphan drug tax credits, partially offset by non-deductible contingent consideration expense associated with Lumara Health.

For the three months ended March 31, 2015, we recognized income tax expense of $5.6 million, representing an effective tax rate of 30%. The difference between the expected statutory federal tax rate of 35% and the 30% effective tax rate for the three months ended March 31, 2015, was attributable to the impact of state income taxes, partially offset by the net benefit of federal orphan drug tax credits and the impact of a valuation allowance release related to certain deferred tax assets.