Income Taxes

3 Months Ended

Mar. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

INCOME TAXES

The following table presents a reconciliation of the federal statutory corporate income tax rate to the effective income tax rate for the three months ended March 31, 2020 and 2019:

	Ameren		Ameren Missouri		Ameren Illinois
	2020	2019	2020	2019	2020	2019
Three Months
Federal statutory corporate income tax rate:	21%	21%	21%	21%	21%	21%
Increases (decreases) from:
Amortization of excess deferred taxes	(9)	(7)	(15)	(12)	(3)	(3)
Depreciation differences	(1)	—	—	—	(1)	—
Amortization of deferred investment tax credit	—	(1)	(1)	(1)	—	—
State tax	6	6	3	4	7	7
Stock-based compensation	(5)	(7)	—	—	—	—
Other permanent items	—	—	—	(3)	—	—
Effective income tax rate	12%	12%	8%	9%	24%	25%