Master Beneficiary Summary File (MBSF) Base A/B/C/D V2

The MBSF base segment includes beneficiary enrollment information, (A/B/C/D). Medicare Advantage (Part C) and the Prescription Drug Program (Part D) plan enrollment information is included.

What does this file include? (variable highlights)

  • State, county annual SSA codes
  • State, county monthly FIPS codes
  • Zip code, State and County
  • Date of birth, date of death
  • Race
  • Reason for entitlement
  • Monthly enrollment for each part of the Medicare program, A/B/C/D
  • Dual eligible status
  • Part C plan and enrollment information
  • Part D plan and enrollment information
  • Part D low income cost sharing
  • Social Security disability status variables

Special considerations

Availability of this file

Availability:
CY 2023

Prior to 2023 data, the MBSF Base A/B/C/D file was used.

Date Requests Can Be Accepted for Upcoming Releases:

CY 2024 available 11/2025

See what is in this file