A U.S. Department of Health and Human Services (HHS) inspector general (IG) audit of Humana’s Medicare Advantage contract found that Humana did not submit some diagnosis codes to the Centers for Medicare and Medicaid Services (CMS) in accordance with federal requirements, resulting in at least $197.7 million in overpayments for 2015. The IG found these errors occurred because Humana’s policies and procedures to prevent, detect, and correct noncompliance with CMS’s program requirements were not always effective. The IG recommended that Humana refund the overpayments and enhance its policies and procedures to prevent, detect, and correct noncompliance with federal requirements for diagnosis codes that are used to calculate risk-adjusted payments.