Case Backlog and Transparency Act of 2020 This bill amends reporting requirements related to Department of Homeland Security (DHS) efforts to address the backlog in immigration applications. DHS shall publish on its website and submit to Congress quarterly reports about the backlog. These reports shall include an annual report that contains information including (1) an analysis of factors contributing to the backlog, (2) a description of existing and planned policies to address the backlog, (3) state-by-state backlog data, and (4) approval and denial rates for each immigration benefit type. The Government Accountability Office shall publish on its website and submit to Congress reports every two years assessing DHS efforts to address the backlog and to ensure fair and accurate adjudication of immigration benefit applications.