It takes half a million dollars per year to maintain each sergeant in combat in Iraq. Thanks to a Senate committee inquiry, an authoritative government study finally details the costs of keeping boots on the ground. The Congressional Budget Office (CBO), in its report Contractors' Support of U.S. Operations in Iraq, compared the costs of maintaining a Blackwater professional armed guard versus the U.S. military providing such services itself. Both came in at about $500,000 per person per year. zFacts: National Debt Graph: Bush Sets 50-Year Record.