The Medicare Recovery Audit Contractor (RAC) program aims to identify and correct overpayments and underpayments made to Medicare providers. From 2005-2008, RAC audits recovered over $900 million in overpayments while reimbursing $38 million in underpayments. The RAC program divides the US into 4 regions, each with a contractor responsible for reviewing medical records and investigating potential improper payments. The goal is to prevent future improper payments by providing payment analyses to the Centers for Medicare and Medicaid Services.