The Recovery Audit Contractor (RAC) Program has become permanent by statute, and RACs have expanded their focus and efforts to identify improper Medicare payments in all 50 states. Physicians and practice groups that bill Medicare Parts A and B may be subject to a RAC Audit. There are two types of RAC reviews and audits, and there are five levels of appeals available to providers when Medicare claims are denied or a RAC audit identifies a previous Medicare overpayment. Physicians and practice groups should take steps to ensure compliance with Medicare regulations and to be prepared prior to receiving a letter from a RAC.