Glossary / MBI
MBI Medicare Beneficiary IdentifierMBI (Medicare Beneficiary Identifier)
The 11-character ID on the Medicare card that replaced the SSN-based HICN; the SWO may use the MBI in place of the beneficiary's name.
The Medicare Beneficiary Identifier (MBI) is the 11-character number printed on the Medicare card. It replaced the Social Security-based Health Insurance Claim Number (HICN) and has been mandatory on Medicare transactions since January 1, 2020 regardless of the date of service, with narrow exceptions for appeals and certain audits.
The format is fixed: characters 2, 5, 8, and 9 are always letters; characters 1, 4, 7, 10, and 11 are always numbers; the rest can be either. The letters S, L, O, I, B, and Z are never used, to avoid confusion with numbers. MBIs are randomly generated with no embedded meaning, and CMS treats them as confidential personal information to be protected like a Social Security number.
For DME paperwork, the MBI is one of the two ways to identify the patient on a Standard Written Order (name or MBI), and it is the identifier on prior authorization requests, ADR cover sheets, and claims. If a claim rejects on the identifier, check eligibility and use the MBI lookup tool in your MAC portal.
Common questions
What do I do if the MBI on file stops working?
Check eligibility through the MAC portal and use its MBI lookup tool. The patient may have been issued a new card.
Do I need both the name and the MBI on the order?
42 CFR 410.38(d) requires the beneficiary's name or MBI. Most orders carry both, which also makes it easier to match the order to the chart notes.
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Sources: CMS: Medicare Beneficiary Identifiers (MBIs) · CMS: Understanding the MBI format · 42 CFR 410.38(d) — Standard Written Order elements . Definitions summarize public Medicare policy and are not legal or billing advice.
More terms
- ADR — Additional Documentation Request
- Prior authorization
- Affirmation and non-affirmation
- UTN — Unique Tracking Number
- SWO — Standard Written Order
- Face-to-face encounter
- DME MAC — Durable Medical Equipment Medicare Administrative Contractor
- Jurisdiction
- PTAN — Provider Transaction Access Number
- NPI — National Provider Identifier
- LCD — Local Coverage Determination
- NCD — National Coverage Determination
- Policy article
- HCPCS — Healthcare Common Procedure Coding System
- Length of need
- Prior authorization exemption
- Competitive bidding
- CMN and DIF — Certificate of Medical Necessity and DME Information Form
- Proof of delivery
- TPE — Targeted Probe and Educate
- Prepayment review