Denominator File - LDS

Alert September 8, 2017: Note that the Denominator LDS file will be replaced by the Master Beneficiary Summary File (MBSF) LDS file beginning with calendar year 2017. For calendar year 2016 data, both the Denominator and MBSF will be available for request. To learn more about the MBSF LDS, please visit, /Research-Statistics-Data-and-Systems/Files-for-Order/LimitedDataSets/MBSF-LDS.

Alert May 5, 2016:  CMS is pleased to announce that all researchers will be allowed to request LDS Denominator data on a quarterly basis.  Historically, researchers have only been able to request annual extracts of Medicare enrollment data under the LDS request process.  Researchers now have the option of requesting the LDS Denominator file on an annual or quarterly basis making it easier to do the important research that will lay the foundation for better quality and lower costs in the health care system.

The Denominator File combines Medicare beneficiary entitlement status information from administrative enrollment records with third-party payer information and GHP enrollment information. The Denominator File contains data on all Medicare beneficiaries enrolled and/or entitled in a given year. It is an abbreviated version of the Enrollment Data Base (EDB) (selected data elements). It does not contain data on all beneficiaries ever entitled to Medicare. The file contains data only for beneficiaries who were entitled during the year of the data. These data are available annually in May of the current year for the prior year.

For file cost and availability, please see the LDS Worksheet (ZIP).

Please follow the instructions on the DUA - Limited Data Sets page.