17. INCOME TAXES

The following table presents the income tax expense (benefit) and the effective tax rates (in thousands):

	Three Months Ended
	March 31, 2015			March 31, 2014
Income tax expense (benefit)	$	6,356		$	(3,618	)
Effective tax rate		23.1	%		47.5	%

For the three months ended March 31, 2015 and 2014, the Company recorded income tax expense of $6.4 million and an income tax benefit of $3.6 million, respectively. The effective tax rates for the three months ended March 31, 2015 and 2014 were 23.1% and 47.5%, respectively, and differ from the U.S. federal statutory rate of 35% primarily due to impacts associated with proportional earnings from the Company’s operations in lower tax jurisdictions, recurring permanent adjustments, and discrete benefits recorded during these periods. For the three months ended March 31, 2015, a discrete benefit of $0.6 million was recorded for benefits realized on disqualifying dispositions of stock from the Company’s employee stock purchase plan. For the three months ended March 31, 2014, a discrete benefit of $1.3 million was recorded for tax benefits realized on disqualifying dispositions of stock from the Company’s employee stock purchase plan, and a discrete tax benefit of $0.9 million was recorded as a result of stock-based compensation expense adjustments related to certain terminated employees.

As of March 31, 2015, the amount of gross unrecognized tax benefits was $21.7 million, all of which would affect the Company’s effective tax rate if realized. The Company recognizes interest income and interest expense and penalties on tax overpayments and underpayments within income tax expense. As of March 31, 2015 and December 31, 2014, the Company had approximately $1.7 million and $1.6 million, respectively, of accrued interest and penalties related to uncertain tax positions. The Company anticipates that, except for $0.6 million in uncertain tax positions that may be reduced related to the lapse of various statutes of limitation, there will be no material changes in uncertain tax positions in the next 12 months.

The Company regularly assesses the ability to realize deferred tax assets recorded in all entities based upon the weight of available evidence, including such factors as recent earnings history and expected future taxable income. If the Company’s future business profits do not support the realization of deferred tax assets, a valuation allowance could be recorded in the foreseeable future. In the event that the Company changes its determination as to the amount of deferred tax assets that can be realized, the Company will adjust its valuation allowance with a corresponding impact to the provision for income taxes in the period in which such determination is made.