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,
	2020			2019
Pretax income	$	38,736		$	31,595
Provision for income taxes	$	9,604		$	6,407
Effective rate		24.8	%		20.3	%

As of December 31, 2019, a valuation allowance of $45.0 million was maintained with respect to our foreign tax credits and state net operating losses. After considering both positive and negative evidence related to the realization of the deferred tax assets, we have determined that it is necessary to continue to maintain a $45.0 million valuation allowance against our foreign tax credits and state net operating losses as of March 31, 2020.

The effective tax rate for the quarters ended March 31, 2020 and 2019 was benefitted by the tax effect of stock-based compensation and the release of previously recorded tax reserves. The effect of these discrete items decreased the effective tax rate for the quarters ended March 31, 2020 and 2019 by 1.9% and 5.6%, respectively.

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 $1.4 million in the next twelve months as a result of the completion of various tax audits currently in process and the expiration of the statute of limitations in several jurisdictions. The income tax rate for the quarter ended March 31,

2020 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, 2020, 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.