The GAO found that federal offices have challenges like the private sector. In comparing building capacity to employees, none used over 50% and some used only 9%. WASHINGTON – The Agriculture Department is headquartered at the gateway between Washington and Virginia in a building rich with history – but on any given day, roughly 90% of it sits empty. That’s not an anomaly. The Government Accountability Office (GAO) surveyed two dozen federal agencies and found they averaged a roughly 80% vacancy rate during the study period earlier this year. Not a single agency topped 50% use, GAO reported.