Income Taxes Income Taxes (Tables)

9 Months Ended

Sep. 30, 2020

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

The following table presents a reconciliation of the federal statutory corporate income tax rate to the effective income tax rate for the three and nine months ended September 30, 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 deferred investment tax credit	(1)		(1)	(1)		(1)	—	—
Amortization of excess deferred taxes	(9)	(a)	(7)	(16)	(a)	(11)	(3)	(3)
Depreciation differences	—		—	—		—	(1)	—
Renewable and other tax credits	(1)		—	(2)		—	—	—
State tax	4		6	4		5	7	6
Stock-based compensation	1		1	—		—	—	—
Effective income tax rate	15%		20%	6%		14%	24%	24%

	Ameren			Ameren Missouri			Ameren Illinois
	2020		2019	2020		2019	2020	2019
Nine Months
Federal statutory corporate income tax rate:	21%		21%	21%		21%	21%	21%
Increases (decreases) from:
Amortization of deferred investment tax credit	—		(1)	(1)		(1)	—	—
Amortization of excess deferred taxes	(9)	(a)	(7)	(16)	(a)	(12)	(3)	(4)
Renewable and other tax credits	(1)		—	(1)		—	—	—
State tax	5		6	3		5	7	7
Stock-based compensation	(1)		(1)	—		—	—	—
Effective income tax rate	15%		18%	6%		13%	25%	24%

(a)Increase in the amortization of excess deferred taxes pursuant to the MoPSC’s March 2020 electric rate order. See Note 2 – Rate and Regulatory Matters for additional information.