Income taxes



	For the three months ended June 30				For the six months ended June 30
(in millions of Canadian dollars)	2016		2015		2016		2015
Current income tax expense	$	27	$	103	$	104	$	205
Deferred income tax expense	90		74		183		106
Income tax expense	$	117	$	177	$	287	$	311

The estimated 2016 annual effective tax rate for the three and six months ended June 30, 2016, excluding the discrete item related to the foreign exchange gain on the Company’s U.S. dollar-denominated debt, is 26.93% and 27.25%, respectively, compared to the estimate of 27.50% for the same periods in 2015.

The effective tax rate for the three and six months ended June 30, 2016, including the discrete item, is 26.40% and 24.86%, respectively, compared to 31.30% and 30.51%, respectively, for the same period in 2015.