What you need to know before you submit a request


You've defined your research question and study objectives and you need CMS data to begin your research. Here are some things you need to know or have completed before preparing a request to ResDAC for CMS data.

Know which files you need

CMS offers over 50 different data files for research purposes. They include administrative (claims), enrollment, assessments, and surveys. Explore the different data files to learn about their contents.

Often, more than one file is needed to complete a research study. Review the files and years that are currently available as listed.  If you are still not sure of the files needed, contact ResDAC.

Define and estimate the study cohort

You may only request the minimum data necessary to accomplish the study aims and you will need to provide a description of how the cohort is defined in your study protocol. Please consider the following factors when defining your cohort:

  • Beneficiary demographics? (age, gender, entitlement status, geographic location, etc.)
  • Service characteristics? (diagnosis, procedure, dates of service, geographic area, etc.)
  • Known cohort? (submitting identifiers, such as SSNs to link)

Resource: Medicare Data Finder and Crosswalk Files

The number of beneficiaries in the cohort will impact the fees that are charged if you are receiving physical delivery of data and may increase the cost in the VRDC for additional storage.

  • VRDC: Size of the cohort may impact the number of storage blocks needed to analyze the data.
  • Physical Data: Size of the cohort impacts the fee charged per file/year.

Resource: CCW Estimate Study Size

Resource: CMS Fee Information for CMS Research Identifiable Data

Determine how you will access data

CMS offers two options to access data, through a virtual connection or physical receipt. The information required for the request and the fees differ depending on access. 

Access data through the Virtual Research Data Center (VRDC)

  • Secure and efficient means to access and analyze data
  • Lower infrastructure cost to the organization since all data and files are stored in VRDC
  • Faster access to data
  • Upload data into the environment and download aggregate de-identified data

Physical receipt of the data files by hard drive

  • Beneficial for users requesting limited quantity of data files
  • Beneficial for users working with non-CMS data that cannot be uploaded to the VRDC
  • Beneficial for users using specialized software, tools or both

Estimate the cost of the request and secure funding

The cost for a CMS data request can vary greatly, so it is important to estimate the total fee for the study in advance of submitting a request and secure funding. CMS can only accept requests that have already secured funding.

Privacy and security of data

Each request for research identifiable data requires a data management plan that outlines the administrative, physical and technical safeguards, and incident response preparedness.

Resources for requests involving physical receipt of the data:

Resources for requests involving access through the Virtual Research Data Center (VRDC):

Obtain IRB review

CMS must ensure that all research requests for identifiable (RIF) data have Institutional Review Board (IRB) documentation to satisfy the requirements of the Common Rule and the Health Insurance Portability and Accountability Act (HIPAA). IRB documentation will need to accompany the data request.


Read the RIF request disclaimers

Requesters of CMS data are solely responsible for the completeness and accuracy of their data request.

During the request process, the requester will be asked to explicitly confirm the accuracy of the request and acknowledge the disclaimers when submitting the signed documents to ResDAC.