A House panel says a Pentagon program for providing civilian employees in Iraq and Afghanistan with workman’s compensation has allowed defense contractors and insurance companies to gouge American taxpayers.

Insurance companies alone have pocketed $600 million in excessive profits over the past five years, according to a staff report released Thursday by the House Oversight and Government Reform Committee.

That’s because the Pentagon lets its contractors negotiate their own insurance contracts. By contrast, the State Department, U.S. Agency for International Development and the Army Corps of Engineers have all selected a single insurance carrier to provide the insurance at fixed rates.