Medicare's Transition Away from SSNs to Medicare Beneficiary Identifiers (MBIs) [7/10/18]


By law, the Centers for Medicare & Medicaid Services (CMS) will remove Social Security Numbers (SSNs) from all Medicare cards by April 2019. CMS is taking this step in an effort protect people with Medicare from fraudulent use of SSNs.

Medicare began issuing new cards that include the MBI in April 2018 and will completely transition to the new format by April 2019.

A couple of notable differences with regard to the new format:

(1) The MBI contains letters and numbers. For example: 1EG4-TE5-MK73
The MBI’s 2nd, 5th, 8th, and 9th characters will always be a letter
Characters 1, 4, 7, 10, and 11 will always be a number
The 3rd and 6th characters will be a letter or a number

(2) MBIs are numbers and upper-case letters, however, letters S, L, O, I, B, and Z are excluded to cut down on confusion. For example: the letter I is often confused with a lowercase “L” or the number “1”.