Fast Facts

State-reported data helps the federal government oversee the Medicaid program. Our prior work found issues with the completeness and accuracy of the data in the federal repository and made recommendations.

Since then, federal Medicaid administrators have improved that data. For example, we found that all states provided at least some data in nearly all of the Medicaid-related topic areas, and that the data was generally of acceptable quality. Yet, we also highlighted data on services, payments, and more that did not meet standards. Implementing our open recommendations could help.

Medicaid program oversight is a High Risk area.

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What GAO Found

GAO found that the completeness and accuracy of Transformed Medicaid Statistical Information System (T-MSIS) data have improved. Over the past decade, the Centers for Medicare & Medicaid Services (CMS) has been implementing T-MSIS, which is the agency's initiative to improve state-reported data available for overseeing Medicaid. CMS's assessment of two key T-MSIS data sources reflect these improvements.

I. Priority items. Priority items are areas of data CMS identified as critical for program oversight, such as beneficiary eligibility and managed care. CMS's assessment of states' data submissions for the first 12 priority items identified significant improvement in meeting CMS data standards over a 22-month period. CMS's assessments of additional priority items similarly indicate improved completeness and accuracy.

Improvements in the Number of States Meeting CMS Standards for Transformed Medicaid Statistical Information System Priority Items One through 12

Number of priority items that met standards

Number of states as of October 2018

Number of states as of August 2020

10 or more



7 to 9



6 or less



Source: GAO analysis of the Centers for Medicare & Medicaid Services (CMS) priority item data. │ GAO-21-196

Note: CMS assessed data from all 50 states and the District of Columbia. CMS excluded Wisconsin from its October 2018 assessment, because the state had not submitted sufficient data.

II. Analytic files. Analytic files are publicly available, research-ready T-MSIS data. GAO's review of CMS's assessments found that all states submitted some data for 67 of the 69        topics relevant to their Medicaid programs. This is an improvement from what GAO found in 2017, when none of the six states reviewed submitted all T-MSIS data applicable to their programs. GAO also found that states' data for 52 of the 69 topics were acceptable—meaning that CMS determined most states' data did not have significant problems that would affect their usability.

While CMS's assessments of priority item and analytic file data indicate improvement in the completeness and accuracy of T-MSIS data, GAO also found that these assessments highlight areas where data do not meet the agency's standards. For example, 30 states did not submit acceptable data for inpatient managed care encounters. Accurate encounter data are critical to ensuring that Medicaid managed care beneficiaries obtain covered services and that payments to managed care organizations are appropriate.

GAO has made at least 13 recommendations related to improving T-MSIS data and expediting their use for program oversight. CMS has addressed five of these recommendations, and has not fully addressed eight—including recommendations to improve data for overseeing payments to providers and managed care organizations. Implementing these recommendations would help CMS strengthen program oversight through improved T-MSIS data.

Why GAO Did This Study

Since adding Medicaid to its High Risk List in 2003, GAO has identified multiple limitations in program data affecting CMS's ability to ensure beneficiaries' access to care and proper payments to health care providers. CMS intends T-MSIS be a national repository of data to manage and oversee Medicaid, which served approximately 77 million individuals at an estimated cost of $673 billion in fiscal year 2020. Prior GAO work found issues with the completeness and accuracy of T-MSIS data and recommended that CMS expedite efforts to improve T-MSIS data and to use them for program oversight. CMS has taken steps to improve T-MSIS data and has made some T-MSIS data publicly available. Yet, questions remain about the usability of T-MSIS data for program oversight.

Under the Comptroller General's authority, GAO initiated this review to examine what is known about the completeness and accuracy of T-MSIS data. GAO reviewed CMS's assessments of two T-MSIS data sources: (1) states' submissions of T-MSIS priority items; and (2) the 2016 T-MSIS analytic files, which was the most recent analytic file data available when GAO began this work. GAO also reviewed CMS documents, prior GAO reports, and reports published by others examining T-MSIS data. GAO interviewed officials from CMS and seven states selected based on variation in their progress submitting complete and accurate priority item data, among other factors.

The Department of Health and Human Services provided technical comments on a draft of this report, which GAO incorporated.

For more information, contact Carolyn L. Yocom at (202) 512-7114 or

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