Improved documentation of federal buildings across five agencies could eliminate up to $20 billion in excess costs, according to a new Government Accountability Office report.

Delayed building maintenance and repair backlogs can cost as much as $20 billion from the General Services Administration, and the departments of Energy, Homeland Security, the Interior, and Veterans' Affairs in 2012.

An exact number is hard to find, because of the way the Federal Real Property Council and Federal Financial Accountability Standards Advisory Board maintain their respective databases. This variation in reporting maintenance and backlogs is an issue that needs fixing, the report says.

Inaccurate backlogs cause an obvious issue, making it "difficult for agencies to determine their current progress in managing" them.

Despite alerting the FRPC of the problems a huge backlog would cause, nothing was done by the end of 2012 about "billions of dollars in deferred maintenance and repair on their real property assets," GAO reported.