The CCW data files were designed to facilitate research across the continuum of care, using data files that could be easily merged and analyzed by beneficiary. Each beneficiary in the CCW is assigned a unique, unidentifiable link key, which allows researchers to easily merge data files and perform relevant analyses across different claim types, enrollment files, Part D event data, assessment data, and other CCW file types. CCW data files are available upon request from CMS. While the file record layouts provided below are the standard file record layouts for all CCW data requests, data may be requested for a variety of cohorts (e.g., specific to a research study design, national 5% sample, specific state or other demographic, etc.).

The CCW claims data files have been streamlined to include only those variables determined by CMS to be of value and useful for research or analytic purposes. The data files delivered from the CCW contain a subset of the original source files. Variables used infrequently or not applicable to a particular setting have been removed. The file record layouts listed below provide variable descriptions, variable format, and length for those variables included in the CCW data files. For additional information regarding data file availability, please refer to the ResDAC website.


Useful Medicaid Analytic eXtract (MAX) Data Validation Tables, Data Anomalies Reports, and other data documentation about file content by state and year are also available for review on the Centers for Medicare & Medicaid Services (CMS) web site.

Medicare-Medicaid Linked Enrollee Analytic Data Source (MMLEADS)

MMLEADS is a suite of linked files designed to allow for the examination of all Medicare and Medicaid enrollment and claims data for those who were dually enrolled in both programs.

The MMLEADS Public Use File (PUF) is available on the CMS website.

Accountable Care Organizations (ACO)