National Response Framework Improvement Act of 2020 This bill requires the Federal Emergency Management Agency (FEMA) (1) to provide summaries of any gaps or inefficiencies in the National Response Framework of the Department of Homeland Security based on lessons learned from the COVID-19 (i.e., coronavirus disease 2019) pandemic; and (2) after the end of the pandemic, as part of its after-action review process, to conduct an evaluation of the framework. Such evaluation shall include (1) any updates to the framework determined necessary by FEMA, in coordination with the primary and support agencies of the emergency support functions, based on the gaps or inefficiencies identified; and (2) recommendations on actions relevant agencies can take to address gaps identified. FEMA must brief the congressional homeland security committees on the summaries and conduct biennial evaluations and updates of the framework.