Government Spectrum Valuation Act of 2020 This bill requires estimation of the value of federal electromagnetic spectrum. Specifically, the bill requires (1) the National Telecommunications and Information Administration, in consultation with the Federal Communications Commission and the Office of Management and Budget, to estimate the value of spectrum assigned or allocated to each federal agency; and (2) each agency to report, in its annual budget and financial statement, the estimated value of the spectrum that has been assigned or allocated to it.