A recent GAO report, “Medicaid: More Transparency of and Accountability for Supplemental Payments Are Needed,” reviews federal oversight of supplemental Medicaid payments, including how information in required disproportionate share hospital (DSH) audits and reports facilitates CMS’s oversight of DSH payments. The report also discusses the lack of similar information for non-DSH payments (such as payments to Medicaid providers serving high-cost Medicaid beneficiaries). The GAO suggests that such audits could indicate “the extent to which payments to individual providers are consistent with the Medicaid payment principles of economy and efficiency,” particularly in light of GAO findings that 39 states made non-DSH payments to 505 DSH hospitals that, together with their regular Medicaid payments, exceeded the hospitals’ total costs of providing Medicaid care by about $2.7 billion. The GAO recommends steps to improve the transparency and accountability of supplemental payment, particularly non-DSH supplemental payments, including requiring CMS to: (1) improve state reporting of non-DSH supplemental payments, including requiring annual reporting of payments made to individual facilities; (2) clarify permissible methods for calculating non-DSH supplemental payments; and (3) require states to submit an annual independent certified audit verifying state compliance with permissible methods for calculating non-DSH supplemental payments.