The data used by the Centers for Medicare & Medicaid Services to oversee the Medicaid program is often incomplete and submitted late, according to a new federal report.

The Government Accountability Office questioned the data CMS uses to calculate Medicaid funding for states and review beneficiary claims in a report published Monday. It marks the second time in less than two weeks the federal watchdog has released a report scrutinizing the Medicaid program.

The new report questions the accuracy of data in the CMS-64, a system used to calculate matching Medicaid funds for states, and the Medicaid Statistical Information System, or MSIS, which reports on individual beneficiary claims.

“The CMS-64 and MSIS have the potential to offer a robust view of payments, overall spending, and services in the Medicaid program,” the report’s authors wrote. “However … the usefulness of these data is limited because of issues with completeness, accuracy, and timeliness.”

Expenditure data analyzed by the GAO was found to be incomplete and inaccurate, which may “complicate CMS’ ability to assess the appropriateness of states’ financing,” the report said. Beneficiary utilization data, especially relating to Medicaid managed care, also was noted to be incomplete and often reported up to three years late. That data is used to identify “inappropriate” provider behavior.

“CMS’s continued reliance on inaccurate, incomplete, and untimely data … hamper effective oversight and are inconsistent with federal internal control standards,” the GAO said.

The watchdog recommended that CMS take “immediate” action to improve the data used for Medicaid oversight; the Department of Health and Human Services agreed, noting that the agency “understands the importance of robust, timely and accurate data.”