Government Accountability Office Tags: Government Agency.The Government Accountability Office (GAO) is an independent agency which provides to the United States Congress audit evaluation and investigative services. As such it is part of the legislative branch of the United States government. thumbnail budget ($) 5.57E8 formation date 1921-07-01 formation year 1921-01-01T00:00:00+02:00 headquarter Washington D.C. leader Eugene Louis Dodaro location Washington D.C. number of employees 3350 Learn more... Loading...