CMS Pub. 100-04, ch. 2, § 30.3

The term Medicare beneficiary identifier (Mbi) is a general term describing a

beneficiary's Medicare identification number. For purposes of this manual, Medicare

beneficiary identifier references both the Health Insurance Claim Number (HICN) and

the Medicare Beneficiary Identifier (MBI) during the new Medicare card transition

period and after for certain business areas that will continue to use the HICN as part of

their processes.

The SSO may issue a temporary health insurance eligibility notice, pending the issuance

of a health insurance card, when the beneficiary is in need of immediate medical services.

The provider may obtain the patient’s name and Medicare beneficiary identifier from the

temporary eligibility notice. See Chapter 2 of the Medicare General Information,

Eligibility, and Entitlement Manual for an example of the temporary notice.

For claims processed by the A/B MAC (B) or DME MAC, the individual, the

individual’s physician, or other supplier must show the Medicare beneficiary identifier on

the request for Medicare payment and on other related bills and documents. Because

Health Insurance records are maintained by the individual’s Medicare beneficiary

identifier, the Medicare beneficiary identifier must be used on all communications.

claim number, the claim number must be used on all communications.