Our Denominator (DN) files have the following data on individuals enrolled in Medicare between 1991 and 1998:
For 1999 - 2021 data, refer to the Master Beneficiary Summary File (MBSF) - Base Segment File page.
The table below lists variable categories for and some key variables in Denominator (DN) data. For a full list of variables, review the DN data dictionary.
Age, Beneficiary Identification Number, Date of Birth, Date of Death, Gender, Race, Residence County Code, Residence State, Residence Zip Code
Eligibility & Enrollment
Monthly Enrollment Counts (A/B/Both), Monthly Managed Care Indicator (Yes/No), Reasons for Entitlement, State Buy-In Indicators
1991 - 1998
File Update Frequency
Data Dictionary LinkVisit the Data Documentation Page
NIA Data Partners Offering DN
HABC, HRS, LLFS, NLTCS, NSHAP, PSAD, PSID, RADC, WLS
NIA Data Partners Not Offering DN
BLSA, CE, NHAS, NHATS, PT, UAS, UFOVT
Additional ResourcesMaster Beneficiary Summary File (MBSF) - Base Segment Files