Income taxes (Tables)

12 Months Ended

Dec. 31, 2020

Summary of difference between statutory federal income tax rate on income before income taxes and effective income tax rate

The difference between the statutory federal income tax rate on income before income taxes and our effective income tax rate is summarized as follows:


	2020		2019		2018
Statutory federal income tax rate	21.0	%	21.0	%	21.0	%
Patronage exclusion	(21.0)	%	(21.0)	%	(20.8)	%
AMT credit monetization	0.0	%	0.0	%	0.0	%
Other	0.0	%	0.0	%	(0.2)	%
Effective income tax rate	0.0	%	0.0	%	0.0	%

Schedule of components of net deferred tax assets and liabilities

The components of our net deferred tax assets and liabilities as of December 31, 2020 and 2019 were as follows:


	(dollars in thousands)
	2020		2019
Deferred tax assets
Net operating losses	$	—	$	1,123
Tax credits (alternative minimum tax and other)	—		—
Accounting for Rocky Mountain transactions	232,169		231,844
Advance payments	112,394		74,482
Other assets	91,938		88,821
Deferred tax assets	436,501		396,270
Less: Valuation allowance	—		(1,123)
Net deferred tax assets	$	436,501	$	395,147
Deferred tax liabilities
Depreciation	$	254,047	$	258,724
Accounting for Rocky Mountain transactions	119,773		118,021
Other liabilities	63,797		68,035
Deferred tax liabilities	437,617		444,780
Net deferred tax assets/(liabilities)	(1,116)		(49,633)
Less: Patronage exclusion	1,116		49,633
Net deferred taxes	$	—	$	—