INCOME TAXES

The following table summarizes our effective tax rate and income tax benefit for the three months ended March 31, 2017 and 2016 (in thousands except for percentages):



	Three Months Ended March 31,
	2017			2016
Effective tax rate	36		%	25		%
Income tax benefit	$	(20,706	)	$	(2,540	)

For the three months ended March 31, 2017, we recognized an income tax benefit of $20.7 million representing an effective tax rate of 36%. The difference between the expected statutory federal tax rate of 35% and the effective tax rate for the three months ended March 31, 2017, was primarily attributable to the impact of state income taxes and the federal research and development tax credit, partially offset by non-deductible stock compensation and other non-deductible expenses.

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.