The U.S. Government Accountability Office (GAO) is an independent, nonpartisan government agency within the legislative branch that provides auditing, evaluative, and investigative services for the United States Congress. It is the supreme audit institution of the federal government of the United States. It identifies its core "mission values" as: accountability, integrity, and reliability. It is also known as the "congressional watchdog". The agency is headed by the Comptroller General of the United States. The comptroller general is appointed by the president with the advice and consent of the Senate. When a vacancy occurs in the office of the comptroller general, Congress establishes a commission to recommend individuals to the president. The commission consists of the following:the speaker of the United States House of Representatives the president pro tempore of the United States Senate the majority and minority leaders of the House of Representatives and the Senate the chair and ranking member of the Senate Committee on Homeland Security and Governmental Affairs the chair and ranking member of the House Committee on Oversight

The comptroller general of the United States is the director of the Government Accountability Office, a legislative-branch agency established by Congress in 1921 to ensure the fiscal and managerial accountability of the federal government.