Emergency Affordable Housing Act of 2020 This bill enhances provisions of the low-income housing tax credit and adjusts the credit to provide assistance during the COVID-19 (i.e., coronavirus disease 2019) pandemic. Specifically, the bill increases to three years (currently, two years) following an allocation of housing credits, the period for making rehabilitation expenditures for a low-income housing tax credit project; extends to three years the period during which a project may be placed in service and remain eligible for the credit; reduces for a two-year period the financing percentage for an affordable housing project from 50% to 25%; establishes a 4% minimum credit rate for affordable housing projects that received a housing credit allocation after 2019; makes permanent the expansion of the 9% housing tax credit; increases the credit for low-income housing tax credit buildings that designate at least 20% of their occupied units for extremely low-income households; increases the credit during a specified temporary period to compensate for construction or leasing delays due to the COVID-19 pandemic; and allows a credit for low-income housing supportive services.