CMS has begun the transition to Medicare Beneficiary Identifier (MBI) on Medicare cards. Starting April 2018, CMS began mailing new Medicare cards to all people with Medicare on a flow basis, based on geographic location and other factors. Beginning in October 2018, through the transition period (December 2019), when providers submit a claim using a patient’s valid and active Health Insurance Claim Number (HICN), CMS will return both the HICN and the MBI on every remittance advice.