Medicaid Data Sources - General Information

The primary data sources for Medicaid statistical data are the Medicaid Statistical Information System (MSIS), the Medicaid Analytic eXtract (MAX) files, and the CMS-64 reports. The following is a general explanation of these reports and the types of program and financial data collected from the states.

MSIS is the basic source of state-submitted eligibility and claims data on the Medicaid population, their characteristics, utilization, and payments and is available by clicking on the link on the left-side column.

The Medicaid Analytic eXtract (MAX) data – formerly known as State Medicaid Research Files (SMRFs) – are a set of person-level data files derived from MSIS data on Medicaid eligibility, service utilization and payments.  The data are available for all states and the District of Columbia beginning with calendar year 1999.  The data are available for selected states prior to 1999.  These data are developed to support research and policy analysis initiatives for Medicaid and other low-income populations.

The MAX data for 1999 have been used to develop a series of research products related to pharmacy benefit use and reimbursement in Medicaid.  These products include a Statistical Compendium of detailed statistics, by state; a Chartbook of Medicaid pharmacy benefit use and reimbursement; and a summary of major Medicaid pharmacy benefit features for 1999, by state.

The CMS-64, 37, and 21 reports are products of the Medicaid and SCHIP Budget and Expenditure Systems (MBES/CBES), the financial budget and grant systems.  A more detailed decription of these reports, along with summary data available as downloadable spreadsheet files, is available in other sections of this site (please refer to the "Related Links Inside CMS" section at the bottom of this page).

Users of Medicaid data may note apparent inconsistencies which are primarily due to the difference in the information captured in MSIS, or the former HCFA-2082, versus CMS-64 reports. The most substantive difference is due to payments made to "disproportionate share hospitals." Disproportionate share hospitals receive higher Medicaid reimbursement than other hospitals because they treat a disproportionate share of Medicaid patients. States determine if hospitals meet the criteria to be considered a "disproportionate share hospital" and establish a formula used to calculate the amount of the payment, subject to certain minimum standards under the law. States claim the Federal match for payments to disproportionate share hospitals on the CMS-64. States combine this claim either with other inpatient hospital services claims or with mental health facility claims. However, payments to disproportionate share hospitals do not appear in MSIS since states directly reimburse these hospitals and there is no fee-for-service billing.

Other less significant differences between MSIS and the CMS-64 occur because adjudicated claims data are used in MSIS versus the reporting of actual payments reflected in the CMS-64. Differences also may occur because of internal state practices for capturing and reporting these data through two separate systems. Finally, national totals for the CMS-64 are different because they include other jurisdictions, such as the Northern Mariana Islands, and American Samoa.

Additional information regarding the Medicaid program and Medicaid expenditures is available through the Department of Health and Human Services Office of the Assistant Secretary for Planning and Evaluation.  Links to this material are listed below in the "Related Links Outside CMS" section at the bottom of this page.