INCOME TAXES

Income tax expense was $59 million for the three months ended March 31, 2016, compared to income tax expense of $9 million in the same period of 2015. For the three months ended March 31, 2016, changes in the effective tax rate from the prior period include tax planning strategies made available in the first quarter of 2015 resulting in releases of tax valuation allowances in 2015. The following table summarizes the difference between income tax expense at the United States statutory rate of 35% and the income tax expense at effective worldwide tax rates for the respective periods:



	Three Months Ended March 31,
Millions of dollars	2016			2015
Earnings before income taxes	$	215		$	207

Income tax expense computed at United States statutory tax rate	75			72
Valuation allowance releases	—			(58		)
U.S. foreign income items, net of credits	(5		)	(2		)
Foreign government tax incentive	(2		)	(4		)
Other	(9		)	1
Income tax expense computed at effective worldwide tax rates	$	59		$	9

At the end of each interim period, we make our best estimate of the effective tax rate expected to be applicable for the full fiscal year and the impact of discrete items, if any, and adjust the quarterly rate as necessary.