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November 21, 2019

Eligibility Inquiries: What to Do If the MBI Changes

CMS recently issued instructions explaining how to do an eligibility search when a new Medicare Beneficiary Identifier (MBI) is issued. For example, the Medicare beneficiary, their authorized representative, or CMS could request a new number if the MBI is compromised. The patient might need to receive or refill a DMEPOS item before their new card with the new MBI is received.

For established patients and customers, it is always a good idea to check eligibility before submitting a claim to Medicare to ensure nothing has changed.

When checking eligibility using the myCGS portal or the Interactive Voice Response (IVR) and you receive error message "Invalid MBI", your patient's MBI may have changed.

Use the MBI Lookup Tool in myCGS to obtain the new MBI. Sign up for myCGS to use the tool.

Eligibility inquiries:


Every person with Medicare has been assigned a Medicare Beneficiary Identifier (MBI) and issued a new Medicare card. The MBI is confidential and should be protected as Personally Identifiable Information.

Do not wait until January 1, 2020, to start using MBIs! Use the transition period as a live test to make sure you are ready to use MBIs for all of your Medicare transactions, including claim submission, reopening requests, prior authorization requests, and eligibility inquiries.

January 1, 2020:

For more information about obtaining and using MBI's, please refer to the CGS Medicare Beneficiary Identifier (MBI) page and New Medicare Beneficiary Identifier (MBI) Get It, Use ItExternal PDF [MLN Matters SE18006]

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