Also known as: Enrollee, Medicare beneficiary, Medicaid beneficiary, Plan member
Key facts
- Medicare ID
- Medicare Beneficiary Identifier (MBI), 11 characters
- MBI replaced
- Social Security number-based Health Insurance Claim Number (HICN)
- MBI required on claims
- Since January 1, 2020, with limited exceptions
- ERISA meaning
- A person designated by a participant or the plan to receive benefits
- CMS public data
- Counts from 1 to 10 are typically suppressed to protect privacy
What is a beneficiary?
In government health programs, beneficiary is the standard word for a covered person. CMS refers to Medicare beneficiaries and Medicaid beneficiaries, and many federal datasets count people using that term.
The word has a narrower meaning in employer plans. Under the Employee Retirement Income Security Act of 1974 (ERISA), the participant is usually the employee, and a beneficiary is a person designated by the participant or by the plan, such as a spouse or child, who may become entitled to benefits.
Being eligible is not the same as being a beneficiary. A person can be eligible for Medicare or Medicaid without being enrolled, and most data sources report enrolled people.
How beneficiaries are identified
Each program uses its own identifiers, and they do not link to each other directly:
- Medicare issues each beneficiary a Medicare Beneficiary Identifier (MBI), a randomly generated 11-character code of numbers and uppercase letters that contains no personal information.
- CMS replaced Social Security number-based Health Insurance Claim Numbers with MBIs on new Medicare cards mailed starting in 2018.
- Each state Medicaid program assigns its own ID numbers, so the same person has different identifiers in Medicaid and Medicare.
- Commercial plans assign their own member IDs.
Why the term matters in data
Beneficiary counts are the denominator for many measures, such as spending per beneficiary, prescribing rates and quality scores. In CMS provider utilization files, a count of beneficiaries is not the same as a count of services or claims: one beneficiary can generate many claims, so volume rankings change depending on which column is used. For provider targeting, the number of distinct beneficiaries a physician treats is often a better measure of reach than total services.
CMS also applies small cell suppression to public files, typically hiding counts between 1 and 10, so low-volume providers and rare drugs can appear to have missing data rather than zero activity.