Countdown: The CMS Transition to New Medicare Identification Numbers

April 4, 2018

In April, 2018, Medicare will begin mailing new Medicare cards to beneficiaries to comply with the mandate to remove Social Security Numbers (SSNs) from all Medicare cards by April 2019.  With over 55 million Medicare beneficiaries set to receive new cards, the year-long distribution of mailings will follow a geographic schedule with the first wave to include the Middle Atlantic States such as Delaware and Maryland, and Western states such as California and Oregon, plus Pacific territories like Guam.

What will the change look like?

Currently a beneficiary’s Medicare ID number is based on his or her SSN.  To help minimize the risk of identity theft, CMS is replacing these numbers with new numbers that will be referred to as a Medicare Beneficiary Identifier (MBI).  As seen in the PDF below, the new numbers are 11 characters long, comprised of a combination of numbers and uppercase letters, and will be randomly generated.

How are the new numbers being implemented?

A transition period of one year has been designated where either number – old or new – can be used for billing purposes, claims and eligibility status and other beneficiary interactions with Medicare.  However, both numbers cannot be used on the same transaction.  The transition period starts 4/1/2018 and will run through 4/1/2019.  It is important to note that new enrollees to Medicare during the transition period will only receive the new number so it is essential that all systems have the capability to accept the new format by April 1, 2018.

Does the change apply to those enrolled in a Medicare Advantage plan?

No.   The change only applies to Medicare beneficiaries and Railroad Medicare plans.  Those enrolled in a Medicare Advantage plan, such as an HMO or PPO, will continue to use their plan’s ID number/card as these plans already have a unique ID number that is not the social security number.

Will APS’ systems be able to accommodate the new number format on April 1, 2018?

Yes.  APS has configured its systems to accommodate both formats – old and new – in keeping with the timeline of the transition period.

For additional details on this initiative, reference the Medicare Learning Network Fact Sheet at: