In response to a May 2023 data breach, the Centers for Medicare and Medicaid Services (CMS) has notified Medicare beneficiaries who may have been affected. The agency is mailing approximately 47,000 new Medicare cards with a new Medicare Beneficiary Identifier (MBI) to those affected.  LeadingAge members who want to learn what do to if a resident or patient’s MBI changes can read this CMS explainer, What do Medicare Beneficiary Identifiers (MBIs) Mean for Health Providers and Office Managers?.  Tips: Ask your resident/patient for their new Medicare card if you get “invalid member ID” when checking Medicare eligibility. Access your Medicare Administrative Contractor’s secure internet portal to use the MBI look-up tool if your resident/patient didn’t get a new Medicare card yet.