13. Income Taxes

The following table provides details of income taxes for the periods indicated:

	Three Months Ended October 31,						Nine Months Ended October 31,
	2017			2016			2017			2016
	(in thousands)
Income before income taxes	$	15,437		$	29,802		$	23,736		$	40,610
Provision for income taxes		3,713		757				6,145			1,150
Effective tax rate	24.1		%	2.5		%	25.9		%	2.8		%

The effective tax rate increased for the three and nine months ended October 31, 2017 compared to the same periods in the prior fiscal year primarily due to a decrease in the proportion of profits generated in lower tax jurisdictions, and an increase in non-deductible stock-based compensation expense, partially offset by the benefit attributed to the utilization of R&D credits.

The Company files federal and state income tax returns in the United States and in various foreign jurisdictions. The tax years 2013 to 2017 remain open to examination by U.S. federal tax authorities. The tax years 2007 to 2017 remain open to examination by U.S. state tax authorities. The tax years 2011 to 2017 remain open to examination by foreign tax authorities. Fiscal years outside of the normal statute of limitations remain open to audit by tax authorities due to tax attributes generated in those earlier years, which have been carried forward and may be audited in subsequent years when utilized.

The Company regularly assesses the likelihood of adverse outcomes resulting from potential tax examinations to determine the adequacy of its provision for income taxes. These assessments can require considerable estimates and judgments. As of October 31, 2017, the gross amount of unrecognized tax benefits was approximately $43.9 million. If the estimates of income tax liabilities prove to be less than the ultimate assessment, then a further charge to expense could be required. If events occur and the payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities could result in tax benefits being recognized in the period in which the Company determines the liabilities are no longer necessary. The existing tax positions of the Company continue to generate an increase in the liability for uncertain tax positions. As of October 31, 2017 and January 31, 2017, the Company’s unrecognized tax benefits recorded in other long-term liabilities, including interest, were approximately $5.4 million and $1.9 million, respectively. The Company does not anticipate material changes to its uncertain tax positions during the next twelve months.