New Medicare Card: Using Your MAC’s MBI Look-Up Tool

When you use the Medicare Administrative Contractor (MAC) secure portal Medicare Beneficiary Identifier (MBI) look-up tool, you must use your patient’s own Social Security Number (SSN) along with your patient’s first name, last name, and date of birth. Your patient’s SSN may differ from the number part of the Health Insurance Claim Number (HICN), which uses the SSN of the primary wage earner on whom benefits are based. The original Medicare card, with a HICN, of a spouse, widow, or other dependent will have the SSN of the wage earner; ask for your patient’s SSN to use in the look up tool. If you do not have access to the tool, sign up.

If you use your patient’s SSN and the look-up tool does not return an MBI, be sure you are using the full last name exactly as it appears on the Medicare card. You may want to include any suffix, such as Jr, Sr, or III.


To ensure people with Medicare continue to get health care services, you can use the HICN through December 31, 2019, or until your patient brings in a new card with the new number.


We finished mailing most cards to people with Medicare who live in Wave 1 and 2 states: Alaska, American Samoa, California, Delaware, District of Columbia, Guam, Hawaii, Maryland, Northern Mariana Islands, Pennsylvania, Oregon, Virginia, and West Virginia. If your Medicare patients did not get a card:

  • Print and give them the “Still Waiting for Your New Card?” handout (in English or Spanish).
  • Or, tell them to call 1-800-Medicare (1-800-633-4227). There might be something that needs to be corrected, such as updating their mailing address.

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