At the end of each interim period, the Company makes its best estimate of the annual expected effective income tax rate and applies that rate to its ordinary year-to-date earnings or loss. The income tax provision or benefit related to unusual or infrequent items, if applicable, that will be separately reported or reported net of their related tax effects are individually computed and recognized in the interim period in which those items occur. In addition, the effect of changes in enacted tax laws or rates, tax status, judgment on the realizability of a beginning-of-the-year deferred tax asset in future years or income tax contingencies is recognized in the interim period in which the change occurs.

The computation of the annual expected effective income tax rate at each interim period requires certain estimates and assumptions including, but not limited to, the expected pre-tax income (or loss) for the year, projections of the proportion of income (and/or loss) earned and taxed in respective jurisdictions, permanent and temporary differences, and the likelihood of the realizability of deferred tax assets generated in the current year. Jurisdictions with a projected loss for the year or a year-to-date loss for which no tax benefit or expense can be recognized due to a valuation allowance are excluded from the estimated annual effective tax rate. The impact of such an exclusion could result in a higher or lower effective tax rate during a particular quarter, based upon the composition and timing of actual earnings compared to annual projections. The estimates used to compute the provision or benefit for income taxes may change as new events occur, additional information is obtained or as our tax environment changes. To the extent that the expected annual effective income tax rate changes, the effect of the change on prior interim periods is included in the income tax provision in the period in which the change in estimate occurs.

A summary of the provision for income taxes and the corresponding effective tax rate for the three and nine months ended September 30, 2019 and September 30, 2018, is shown below (in thousands, except effective tax rates):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Income tax expense	$	6,771		$	3,688		$	19,214		$	9,807
Earnings before income tax	$	22,658		$	3,333		$	46,266		$	39,077
Effective tax rate		29.9	%		110.7	%		41.5	%		25.1	%

Income tax expense excluding impairment loss	$	6,771		$	3,688		$	19,214		$	9,807
Earnings before income tax excluding impairment loss	$	23,495		$	14,809		$	67,472		$	50,553
Effective tax rate excluding impairment loss		28.8	%		24.9	%		28.5	%		19.4	%

For the nine months ended September 30, 2019, the Company recognized a loss of $21,206 related to an impairment loss for which no tax benefit was provided. Similarly, for the nine months ended September 30, 2018, the Company recognized a loss of $11,476 related to a non-deductible impairment loss. Income tax expense, earnings before income tax and effective tax rate excluding the impairment loss are noted above.

The Company’s effective tax rate for the three months ended September 30, 2018 included a discrete benefit related to stock-based compensation. For the nine months ended September 30, 2018, the Company’s effective tax rate included a discrete benefit related to certain intercompany transactions which disproportionately benefited lower tax rate jurisdictions.

The annual effective tax rates differ from the U.S. statutory rate primarily due to foreign rates which differ from those in the U.S., U.S. taxes on foreign earnings, the realization of certain business tax credits, including research and development and foreign tax credits, and the applicable withholding taxes on the projected future repatriations of the earnings from the Company’s non-U.S. operations that are not considered permanently reinvested.