10 income taxes


	Three months				Six months
Periods ended June 30 (millions)	2020		2019		2020		2019
Current income tax expense
For the current reporting period	$	83	$	71	$	285	$	197
Adjustments recognized in the current period for income taxes of prior periods		(2)		(1)		(4)		(1)
		81		70		281		196
Deferred income tax expense
Arising from the origination and reversal of temporary differences		32		83		(28)		114
Revaluation of deferred income tax liability to reflect future income tax rates		(2)		(121)		(5)		(121)
Adjustments recognized in the current period for income taxes of prior periods		6		(1)		8		(1)
		36		(39)		(25)		(8)
	$	117	$	31	$	256	$	188

Our income tax expense and effective income tax rate differ from those calculated by applying the applicable statutory rates for the following reasons:


Three-month periods ended June 30 ($ in millions)	2020				2019
Income taxes computed at applicable statutory rates	$	113	26.2	%	$	147	26.7	%
Revaluation of deferred income tax liability to reflect future income tax rates		(2)	(0.5)			(121)	(22.0)
Adjustments recognized in the current period for income taxes of prior periods		4	0.9			(2)	(0.3)
Other		2	0.5			7	1.2
Income tax expense per Consolidated statements of income and other comprehensive income	$	117	27.1	%	$	31	5.6	%

Six-month periods ended June 30 ($ in millions)	2020				2019
Income taxes computed at applicable statutory rates	$	243	26.3	%	$	308	26.9	%
Revaluation of deferred income tax liability to reflect future income tax rates		(5)	(0.5)			(121)	(10.6)
Adjustments recognized in the current period for income taxes of prior periods		4	0.4			(2)	(0.2)
Other		14	1.5			3	0.3
Income tax expense per Consolidated statements of income and other comprehensive income	$	256	27.7	%	$	188	16.4	%