Income Taxes

Income tax provision and effective tax rate are as follows:



	Three Months Ended March 31,
	2019			2018
	(in millions)
Deferred tax provision	$	103		$	50
Effective tax rate	23		%	22		%

Uncertain tax positions. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained upon examination by the taxing authorities based upon the technical merits of the position. As of March 31, 2019 and December 31, 2018, the Company had unrecognized tax benefits ("UTBs") of $141 million for each respective period resulting from research and experimental expenditures related to horizontal drilling and completion innovations. If all or a portion of the UTBs is sustained upon examination by the taxing authorities, the tax benefit will be recorded as a reduction to the Company's deferred tax liability and will affect the Company's effective tax rate in the period it is recorded. The timing as to when the Company will substantially resolve the uncertainties associated with the UTBs is uncertain.

The Company files income tax returns in the U.S. federal and various state and foreign jurisdictions. The Internal Revenue Service has closed examinations of the 2011 and prior tax years and, with few exceptions, the Company believes that it is no longer subject to examinations by state and foreign tax authorities for years before 2012. As of March 31, 2019, no adjustments had been proposed in any jurisdiction that would have a significant effect on the Company's liquidity, future results of operations or financial position.