Medicare Recovery Audit Contractors (RACs) mine data using automated systems to detect and recover improper Medicare payments. RAC audits pick up billing and coding errors and deny claims based on those errors. In many instances, the service was provided and was billable. In some cases, the coding error makes no difference in reimbursement, sometimes reimbursement should be higher, sometimes lower, but still reimbursable, under some code. In some cases, the RAC’s automated systems deny claims that were properly billed, because of software coding flaws. RAC auditors don’t correct billing errors, they just take the money back.