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Master Beneficiary Summary File (MBSF) LDS

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.

Submitting a data request: Please follow the instructions on the DUA - Limited Data Sets page.