9. INCOME TAXES

The determination of the annual effective tax is based upon a number of significant estimates and judgments, including the estimated annual pretax income in each tax jurisdiction in which we operate and the ongoing development of tax planning strategies during the year. In addition, our provision for income taxes can be impacted by changes in tax rates or laws, the finalization of tax audits and reviews, as well as other factors that cannot be predicted with certainty. As such, there can be significant volatility in interim tax provisions.

The following is a summary of our provision for income taxes and effective tax rate from continuing operations (dollars in thousands):

	For the Quarter Ended March 31,
	2018			2017
Pretax income	$	21,382		$	10,098
Provision for income taxes	$	3,498		$	4,501
Effective rate		16.4	%		44.6	%

As of December 31, 2017, a valuation allowance of $50.5 million was maintained with respect to our foreign tax credits, separate state net operating losses and Illinois edge credits. After considering both positive and negative evidence related to the realization of these deferred tax assets, we have determined that it is necessary to continue to record the valuation allowance as of March 31, 2018.

The effective tax rate for the quarter ended March 31, 2018, was primarily impacted by excess tax benefits associated with stock-based compensation and the release of previously recorded tax reserves. The effect of these discrete items decreased the effective tax rate for the quarter by 9.3%. The effective tax rate for the current quarter also reflects the reduction in the U.S. corporate tax rate from 35% to 21% resulting from the enactment of the Tax Cuts and Jobs Act that became effective in January 2018. For the quarter ended March 31, 2017, the effective tax rate was primarily impacted by tax reserves recorded in the quarter and the tax effect of expenses that are not deductible for tax purposes.

We estimate that it is reasonably possible that the gross liability for unrecognized tax benefits for a variety of uncertain tax positions will decrease by up to $1.9 million in the next twelve months as a result of the expiration of the statute of limitations in several jurisdictions. The income tax rate for the quarter ended March 31, 2018 does not take into account the possible reduction of the liability for unrecognized tax benefits. The impact of a reduction to the liability will be treated as a discrete item in the period the reduction occurs. We recognize interest and penalties related to unrecognized tax benefits in tax expense. As of March 31, 2018, we had accrued $1.7 million as an estimate for reasonably possible interest and accrued penalties.

Our tax returns are routinely examined by federal, state and local tax authorities and these audits are at various stages of completion at any given time. The Internal Revenue Service has completed its examination of our U.S. income tax returns through our tax year ended December 31, 2014.