Medicare Eligibility and Enrollment Files, RIF Versions

Purpose

The beneficiary eligibility and enrollment files have changed in content and name over the years. It is important to understand the timing of these changes and the unique features of each file if you are using older files or see them referenced in articles.

Current Version Date:

01/19/2018

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General Contents of the Beneficiary Eligibility and Enrollment Files

In general, the eligibility and enrollment files contain:

Variables used for unique patient identification across files
Demographic information including birth date, death date, and race
Variables used to track enrollment in Medicare over time.
Reason for Medicare eligibility (e.g., aged, disabled or End Stage Renal Disease).
Type of Medicare enrollment, such as enrollment in traditional, fee-for-service Medicare versus Medicare managed care (i.e., Part C)

Note: Each file includes records for all Medicare beneficiaries enrolled at some point during the calendar year.

Evolution of the Files

File Name	Year Introduced	Year Discontinued	Created for Calendar Years	Key Variables Available	Notes
Denominator	Prior to 1999	March 2010	1999-2009	Monthly enrollment/entitlement information for Medicare Part A, B	Created in March of the following CY
				State/county codes	Age calculated as of the beginning of the CY
				Zip code	State and zip code as of March of the following CY
				Date of birth	Deaths reported in the file through March of the following CY
				Date of death
				Demographics (e.g. age, race, sex)
Beneficiary Annual Summary File (BASF)	2006	2011	1997-2010	Monthly enrollment/entitlement information for Medicare Part A, B	Created at the end of the CY
				State/county codes	Stand-alone file containing a combination of enrollment, eligibility, and summary level variables
				Zip code	Included subset of Denominator variables
				Date of birth	Summary reimbursement variables for each claim type (IP, OP, SNF, HHA, Hospice, Carrier, DME)
				Date of death	Condition Categories
				Demographics (e.g. age, race, sex)	Summary utilization variables
				Number of inpatient stays
				Number of physician visits
				Chronic condition flags
Beneficiary Summary File (BSF)	2007	March 2012	1999-2011	Monthly enrollment/entitlement information for Medicare Part A, B, C, and D	Base file contains similar variables as those found in the BSF and Denominator with Part D
				State/county codes	Included all Denominator variables
				Zip code	Included Part D Denominator variables starting in 2008
				Date of birth	Age calculated as of the end of the CY
				Date of death	State and zip code as of the end of the CY
					Included new race variable
Denominator with Part D	2008	March 2010	2006-2009	Monthly enrollment/entitlement information for Medicare Part A, B, C, and D	Included all Denominator variables
				State/county codes	Included the Part D entitlement indicators
				Zip code	Included new dual-eligible variable
				Date of birth	Included expanded race variable
				Date of death
				Demographics (e.g. age, race, sex)
Master Beneficiary Summary File (MBSF): Base	2012	NA	1999-current	Monthly enrollment/entitlement information for Medicare Part A, B, C, and D	Base file contains similar variables as those found in the BSF and Denominator with Part D
				State/county codes	New Medicare Advantage/Part C variables added as of 2017
				Zip code	Age calculated as of the end of the CY
				Date of birth	State and zip code as of the end of the CY
				Date of death
				Demographics (e.g. age, race, sex)
				Medicare Advantage contract number/benefit package
MBSF: Cost and Utilization	2012	NA	1999-current	Number of emergency room visits	Annual, beneficiary-level summarized information on service use and Medicare payment by file type (e.g., inpatient)
				Number of inpatient stays
				Number of physician visits
MBSF: Chronic Conditions	2012	NA	1999-current	Flags for 27 common conditions	Includes the CCW chronic conditions previously found in the BASF
MBSF: National Death Index (NDI)	2012	NA	1999-2021	Date of death	Includes new variables not previously offered
				Cause of death
				State of death
MBSF: Other Chronic or Potentially Disabling Conditions	2015	NA	1999-current	Flags for 35 additional chronic health, mental health, substance abuse, and potentially disabling condition categories beyond the chronic conditions flags above	Includes new chronic conditions not previously offered

Table 1. List of Medicare Beneficiary Eligibility and Enrollment Files Since 1999

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Article Information

Author(s):

Faith Asper, MHS, CIPP/G

Level:

Introduction

Topic:

Data Files or Variables

Program:

Medicare

Category:

Beneficiary Enrollment and Summary

Disclaimer:

The process and materials mentioned as part of this KnowledgeBase article are current, as of the publication date on the article, to the best of our knowledge. The examples provided are correct in the aggregate but may not apply to every subgroup or circumstance that a researcher may wish to study. It is up to the researcher to conduct analysis and confirm that the patterns described in this KnowledgeBase article apply to his/her particular study. If your research findings appear to contradict the advice provided, please contact ResDAC.