Section 6402(a) of the Affordable Care Act (ACA) requires a person who has received an overpayment to report and return the overpayment within 60 days after the date on which it was identified. The Centers for Medicare & Medicaid Services Self-Referral Disclosure Protocol establishes a six-year lookback period. This seems straightforward; however, sometimes looks are deceiving. Providers and suppliers who fail to report and return overpayments face potential False Claims Act (FCA) liability, Civil Monetary Penalties and exclusion from federal health care programs. When there is credible information concerning a potential overpayment, the overpaid provider must undertake reasonable diligence to determine whether an overpayment has been received and the amount. It is essential that trained professionals evaluate the credible evidence to determine its validity and the amount of the overpayment. A provider or supplier waives all rights to appeal if the overpayment is self-disclosed. The mere fact that a Medicare Administrative Contractor alleges overcharges by a provider or supplier does not necessarily obligate the provider to refund the alleged overpayment and relinquish appeal rights. MCA professionals have extensive experience in evaluating and calculating overpayments, when substantiated. MCA’s professional staff includes an experienced doctorate-level statistician who uses the most up-to-date statistically valid audit sampling methodologies. The use of statistical sampling to project overpayments is far less cumbersome and reduces the expense of the audit.