Medicare Beneficiary Identifiers (MBIs)

We removed Social Security Number (SSN)-based Health Insurance Claim Numbers (HICNs) from Medicare cards and are now using Medicare Beneficiary Identifiers (MBIs) for Medicare transactions like billing, eligibility status, and claim status. We worked closely with our business partners:

Every person with Medicare has been assigned an MBI. The MBI is confidential like the SSN and should be protected as Personally Identifiable Information.

You MUST submit claims using MBIs, no matter what date you performed the service, with a few exceptions. 

Medicare plan exceptions:

  • Appeals - People filing appeals can use either the HICN or the MBI for their appeals and related forms.
  • Adjustments - You can use the HICN indefinitely for some systems (Drug Data Processing, Risk Adjustment Processing, and Encounter Data) and for all records, not just adjustments.
    • Reports - We’re using the HICN on these reports until further notice:
      • Incoming to us (quality reporting, Disproportionate Share Hospital data requests, etc.).
      • Outgoing from us (Provider Statistical & Reimbursement Report, etc.)
  • Retrospective reporting - Plans can use the HICN when submitting data for older contract years for applicable systems (e.g., Health Plan Management System).

Fee-for-Service claim exceptions:

  • Appeals - You can use either the HICN or the MBI for claims, appeals and related forms.
  • Audits – You can use either the HICN or the MBI for audit purposes.
  • Claim status query - You can use either the HICN or the MBI to check the status of a claim (276 transactions) if the earliest date of service on the claim is before January 1, 2020. If you're checking the status of a claim with a date of service on or after January 1, 2020, you must use the MBI.
  • Span-date claims - You can use the HICN for 11X-Inpatient Hospital, 32X-Home Health (home health final claims & Request for Anticipated Payments (RAPs)), and 41X-Religious Non-Medical Health Care Institution claims if the “From Date” is before the end of the transition period (12/31/2019). You can submit claims received between April 1, 2018 and December 31, 2019 using either the HICN or the MBI.  If a patient starts getting services in an inpatient hospital, home health, or religious non-medical health care institution before December 31, 2019, you may submit a claim using either the HICN or the MBI, even if you submit it after December 31, 2019.
  • Incoming premium payments - People with Medicare who don't get SSA or RRB benefits and submit premium payments should use the MBI on incoming premium remittances. But, we'll accept the HICN on incoming premium remittances.  (Part A premiums, Part B premiums, Part D income related monthly adjustment amounts, etc.).

What do MBIs look like?

The MBIs are:

  • Clearly different than the HICN and RRB number.
  • 11-characters in length.
  • Made up only of numbers and uppercase letters (no special characters); if you use lowercase letters, our system will convert them to uppercase letters.

The MBI doesn’t use the letters S, L, O, I, B, and Z to avoid confusion between some letters and numbers (e.g., between “0” and “O”). Learn about and use our MBI format specifications (PDF) to make changes to your systems.  

Do the MBI's characters have any meaning?

Each MBI is unique, randomly generated, and the characters are "non-intelligent," which means they don't have any hidden or special meaning.

What do MBIs mean for people with Medicare?

The MBI doesn't change Medicare benefits. 

People with Medicare who belong to a Medicare Advantage plan or a Medicare drug plan (Part D) should keep using their Medicare Advantage and/or Medicare drug plan cards like they always have when they get health care services or fill a prescription. People with Medicare will also need their MBIs when they change plans or are admitted to the hospital.

Where can I get more information about MBIs?

You can:



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Page Last Modified:
09/06/2023 04:51 PM