End Oil and Gas Tax Subsidies Act of 2020 This bill limits or repeals certain fossil fuel oil and gas subsidies for oil companies. Specifically, it increases to seven years the amortization period for geological and geophysical expenditures; repeals the tax credits for producing oil and gas from marginal wells and for enhanced oil recovery; repeals the tax deduction for the intangible drilling and development costs of oil and gas wells; repeals percentage depletion; repeals the tax deduction for tertiary injectant expenses; repeals the passive loss exception for working interests in oil and gas property; denies the tax deduction for income attributable to domestic production activities for oil and gas activities; prohibits the use of the last-in, first-out (LIFO) accounting method by major integrated oil companies; limits the foreign tax credit for dual capacity taxpayers (i.e., taxpayers who are subject to a levy of a foreign country or U.S. possession and receive specific economic benefits from such country or possession); and expands the definition of crude oil for purposes of the excise tax on petroleum and petroleum products to include any oil derived from a bitumen or bituminous mixture (tar sands), and any oil derived from kerogen-bearing sources (oil shale).