Medicare MBI Changes: What Providers Need to Know to Prevent Claim Denials

 TELCOR has noticed an increase in “missing/incomplete/invalid patient identifier” denials from Medicare. 

Effective April 14, 2026, 1.3 million Medicare beneficiaries have new Medicare Beneficiary Identifiers (MBIs). Centers for Medicare & Medicaid Services (CMS) notified beneficiaries of the change and provided new Medicare ID cards by mail in March 2026. Any claim submitted for services rendered after April 13 will need to be submitted with the patient’s new Medicare MBI to prevent denial. This update is in addition to the MBI changes made for over 900,000 beneficiaries in response to the 2023 WPS data breach. CMS has not provided a specific reason for the updates but has stated that the purpose is to prevent fraud. 

- Sarah Stewart, Vice President, RCS