Master Beneficiary Summary File (MBSF) LDS
Guidance for replacement of the Denominator LDS file with the Master Beneficiary Summary File (MBSF) LDS beginning with calendar year 2017. It includes a listing of the differences between the Denominator and the MBSF LDS.
Issued by: Centers for Medicare & Medicaid Services (CMS)
Issue Date: February 11, 2020
The MBSF LDS contains data on all Medicare beneficiaries enrolled in or entitled to Medicare within a given calendar year. The MBSF contains beneficiary characteristics and enrollment information.
The LDS MBSF differs from the Denominator as indicated below:
- Monthly State/County FIPS codes
- Monthly Medicare Status codes
- Monthly Dual Status codes
- Medicare 1, 5, or 20% Strict Sample Group Indicator
The MBSF LDS will replace the Denominator LDS file beginning with calendar year 2017 (both the MBSF and Denominator files will be available during calendar year 2016).
For file cost and availability, please see the LDS Worksheet (ZIP).
Please follow the instructions on the DUA - Limited Data Sets page.
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DISCLAIMER: The contents of this database lack the force and effect of law, except as authorized by law (including Medicare Advantage Rate Announcements and Advance Notices) or as specifically incorporated into a contract. The Department may not cite, use, or rely on any guidance that is not posted on the guidance repository, except to establish historical facts.