Getting Started with CMS Data

Who is in the data?

ResDAC assists researchers with requesting data for two large insurance programs administered by the Centers for Medicare and Medicaid Services (CMS). 

Medicare is a federal health insurance program for those aged 65 and older, certain people under 65 with disabilities, and people of any age with End Stage Renal Disease. Medicare covers about 96% of all US citizens aged 65 and older.

Medicaid is a joint federal/state health insurance program, providing coverage to low-income children, pregnant women, people with disabilities, some elderly and non-elderly adults. While the federal government defines broad national guidelines of eligibility and services, each state’s program establishes its own eligibility standards and determines the scope of services. 

Dual Eligibles are individuals who are enrolled in both Medicare and Medicaid.


Medicare and You Handbook
CMS Program Statistics - Medicare Total Enrollment
Medicaid & CHIP Enrollment Data

What is in the data?

The data contain information needed to run the Medicare and Medicaid programs.

Data are divided into files by type of information and year.  Explore the different types of files available.

What type of data is right for me?

CMS offers different types of data from summarized reports to individual-level data.

The type of data file that is right for you will depend on a number of factors. They are:

  • Level of detail needed
  • Level of customization required
  • Budget available
  • Time to obtain
  • Storage available


Comparison of PUF, LDS, and RIF data


Read more on this topic from the article, "Differences between RIF, LDS, and PUF Data Files".