13. Income taxes

The following table presents the provision for income taxes and our effective tax rate for the three months ended October 31, 2017 and 2016:

	Three Months Ended
	October 31,
(in millions except percentages)	2017			2016
Provision for income taxes	$	2.5		$	1.0
Effective tax rate		30	%		28	%

The effective income tax rate on operations is based upon the estimated income for the year, the composition of the income in different countries, and adjustments, if any, in the applicable quarterly periods for the potential tax consequences, benefits, resolutions of tax audits or other tax contingencies.

Our effective tax rate for the three months ended October 31, 2017 is lower than the statutory rate of 35% primarily due to income generated outside the United States in countries with lower tax rates and tax credits in the United States and Canada, offset by certain discrete tax expense. The tax provision for the three months ended October 31, 2017 includes discrete tax expense totaling $0.5 million.

Our effective tax rate for the three months ended October 31, 2016 lower than the statutory rate of 35% primarily due to income generated outside the United States in countries with lower tax rates, tax credits in the United States and Canada, and the manufacturing deduction in the United States. The tax provision for the three months ended October 31, 2016 includes discrete tax benefits totaling less than $0.1 million.

We are subject to U.S. Federal income tax as well as the income tax of multiple state and foreign jurisdictions. As of October 31, 2017, we have concluded all U.S. Federal income tax matters through the year ended July 31, 2013.

We accrue interest and, if applicable, penalties for any uncertain tax positions. This interest and penalty expense is treated as a component of income tax expense. At October 31, 2017 and July 31, 2017, we had approximately $0.1 million and $0.1 million accrued for interest and penalties on unrecognized tax benefits, respectively.

At October 31, 2017, we had $4.9 million of unrecognized tax benefits for uncertain tax positions and $0.1 million of related accrued interest and penalties. We are unable to reasonably estimate the amount and period in which these liabilities might be paid.

We do not provide for U.S. Federal income taxes on undistributed earnings of consolidated foreign subsidiaries, as such earnings are intended to be indefinitely reinvested in those operations. Determination of the potential deferred income tax liability on these undistributed earnings is not practicable because such liability, if any, is dependent on circumstances that exist if and when remittance occurs. The circumstances that would affect the calculations would be the source location and amount of the distribution, the underlying tax rate already paid on the earnings, foreign withholding taxes and the opportunity to use foreign tax credits.