CMS Data Dictionaries and Resources

Please see the tabs below for more information on the CMS data made available through the SDRC process. This page is organized into two tabs: one tab for data dictionaries and file layouts and one tab for data resources to improve understanding or use of the CMS data.

Please contact the SDRC for any assistance with these files.

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Chronic Conditions Data Warehouse (CCW)

Please see the CCW Data Dictionaries page for information on the following data files:

  • Historical Parts A & B Claims (Inpatient, Outpatient, Skilled Nursing Facility, Hospice, Home Health, Carrier, Durable Medical Equipment)
  • MedPAR
  • Assessments (MDS, OASIS, Swing Bed, and IRF-PAI) data
  • Master Beneficiary Summary File (MBSF)
  • Medicaid Enrollment Supplemental File (MESF)
  • Medicare-Medicaid Linked Enrollee Analytic Data Source (MMLEADS)
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Coordination of Benefits Agreement (COBA)

Please see the Coordination of Benefits Agreement website for more information on the COBA process, including:

  • The Coordination of Benefits Agreement Implementation User Guide contains information about the administrative, technical, and financial requirements for implementing the Coordination of Benefits Agreement (COBA). Emphasis is given to preparing and testing data files to and from the Benefits Coordination & Recovery Center (BCRC).
  • COBA File Formats and Connectivity page with the eligibility (E01) file layouts.
  • HIPAA 5010 COB Claims page contains:

    • The COBA Companion Guide for Health Insurance Portability and Accountability Act (HIPAA) 837 Institutional and Professional Medicare Coordination of Benefits Version 5010 (COB)/Crossover Claim Transactions provides COBA trading partners information for preparing and testing Medicare HIPAA 5010 COB transactions with the BCRC.
    • The COBA Companion Guide for National Council for Prescription Drug Programs (NCPDP) Batch Version D.0 COB/Crossover Claims provides COBA trading partners information for preparing and testing Medicare NCPDP D.0 batch COB transactions with the BCRC.
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Medicare-Medicaid Linked Enrollee Analytic Data Source (MMLEADS)

MMLEADS is a suite of linked data files for Medicare-Medicaid eligibility, enrollment, utilization, and expenditure data. This data source includes health care information for all dually eligible Medicare-Medicaid enrollees, and, for comparison purposes, all Medicare-only beneficiaries and Medicaid-only beneficiaries with disabilities. MMLEADS provides utilization and expenditure metrics based on MMCO’s preferred method of identifying dually eligible population (e.g., from the monthly “State MMA File”), while also keeping the flexibility to generate metrics according to other user-defined criteria. MMLEADS contains a linking variable for linking to other data (e.g., survey, assessment, and claims) that are housed in the Chronic Conditions Warehouse (CCW). 

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The MMLEADS PUF data are based off MMLEADS, version 2.0. The 2006-2012 aggregated data include information on full- and partial-dually eligible population, as well as Medicare-only enrollees and Medicaid-only (eligible via disability) enrollees for comparison purposes. The MMLEADS PUF data and user guide are available for download.

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Prescription Drug Event (PDE) File Layout

The PDE File Layout spreadsheet describes both the structure and variables contained within PDE files.

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File Exchanges and Queries

The Medicare Advantage Prescription Drug State User Guide (MAPD SUG) has information, including file layouts, pertinent to the content of multiple file exchanges including the Medicare Modernization Act (MMA) File Exchange and the Territory & State Beneficiary Query (TBQ) File.

For the MMA File Exchange, see:

  • Section 4, Technical instructions for submitting state data for MMA to view MMA file layouts
  • Section 5, State MMA Request File Timing & Content
  • Section 6, MMA Request File
  • Section 7, MMA Response File

For the TBQ File, see:

  • Section 10, Territory & States Beneficiary Query Request File
  • Section 11, Territory & States Beneficiary Query Response File
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Coordination of Benefits Agreement (COBA) Companion Guides

Benefits Coordination Recovery Center’s COBA HIPAA 5010 Companion Guide

This guide provides information for preparing and testing Health Insurance Portability and Accountability Act of 1996 (HIPAA)5010 COBA transactions. It provides information in understanding what values will appear in various fields on the outbound 837 claims. The Washington Publishing Company (WPC) provides the HIPAA 5010 837-I and 837-P Technical Report Version 3 (TR-3) Guides. These comprehensive guides fully lay out the rules for HIPAA implementation of the 837 claims. There is a charge for these consolidated guides through the Washington Publishing Company.

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Enhancements to the CCW

The CCW contains Medicare and Medicaid claims, eligibility, and enrollment data. The CCW also contains indicators (i.e., “flags”) for 30 chronic conditions, which were originally chosen based on their high prevalence among elderly Medicare-only beneficiaries. The Medicare-Medicaid Coordination Office (MMCO) has expanded these flags for all years of existing data (2000-2008) to include the following: 1) the Medicaid-only population; 2) identification of individuals among the dually eligible population with the original 30 conditions for both Medicare and Medicaid claims, rather than solely their Medicare experience; and 3) additional flags for all three populations with conditions that are known to affect dually eligible population with disabilities and Medicaid-only beneficiaries. MMCO developed and has made available CCW flags for nine mental health conditions, tobacco use, and 18 conditions related to intellectual, developmental, and physical disability with the assistance of subject matter experts.

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Chiapas Tool for Use with COBA Data

Chiapas is a tool offered by SDRC for Medicaid agencies to use to convert the COBA data files from an X12 file format to a flat file (.csv) format. This software comes with a set of pre-defined fields to transform the 837 Institutional (837I) and 837 Professional (837) claims. If you want to access Chiapas and the supporting documents, please contact SDRC directly.

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Part D Prescription Drug Event (PDE) Data and Netting

When a dually eligible beneficiary with Part D coverage fills a prescription, the prescription drug plan submits a record to CMS – this is called a prescription drug event (PDE). The PDE data are not the same as individual drug claim transactions, but are summary extracts using CMS-defined standard fields. The CMS system uses a netting process for the creation of the Part D PDE data files that are sent to participating Medicaid agencies. This netting process differentiates between two versions of a given event. The two key fields used in the netting process are the “Effective Unique ID” and the “Unique ID”. The “Effective Unique ID” is used to tie together all of the versions of a given event that have been received. The “Unique ID” is used to identify each individual record within the event history. For more information on netting for Part D PDE data please refer to the Part D Netting Explanation on the Data Documentation tab.

  • The Part D Netting Explanation document explains the data elements that CMS has developed to enable PDE users to identify and net unique prescription drug claims. Download File
  • The Integrating Monthly Files into Part D Final Action document explains the additional steps necessary to identify final action records within the PDE data when incorporating the monthly update files. Download File
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CMS Public Use Files (PUFs)

For more information on what free, publicly available data files that include Medicare and Medicaid services at the beneficiary and provider levels, data by state, and data file guides are available, please see the SDRC PUF Tip Sheet.

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File Exchanges and Queries

Please see the SDRC websites on the MMA File Exchange, State Buy-in File Exchange, and the TBQ File for more information on using and understanding these files.

Need additional help or information on this process? Contact the SDRC team


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