Medicare changed its ID numbers starting in April 2018, when the Centers for Medicare & Medicaid Services began mailing new cards that replaced the Social Security Number-based Health Insurance Claim Number with a randomly generated Medicare Beneficiary Identifier (MBI). CMS finished mailing the new cards by January 2019, and since January 1, 2020, the MBI has been the only accepted identifier for Medicare claims and eligibility transactions.1Centers for Medicare & Medicaid Services. CMS Finalizes New Medicare Card Distribution Ahead of Deadline, Accelerating Fight Against Medicare Fraud and Abuse
The Timeline in Plain Dates
Congress ordered the change in the Medicare Access and CHIP Reauthorization Act of 2015 (MACRA), setting an April 2019 deadline for CMS to remove Social Security Numbers from all Medicare cards.
- April 2018: CMS began mailing redesigned cards to existing beneficiaries on a rolling, state-by-state schedule.
- January 2019: Mailing was complete, about three months ahead of the congressional deadline.
- April 1, 2018 through December 31, 2019: A transition period during which providers could bill using either the old HICN or the new MBI.
- January 1, 2020: The MBI became the sole accepted identifier. Claims submitted with the old HICN are now rejected, apart from narrow exceptions for internal government processing and certain crossover claims involving dual-eligible beneficiaries.1Centers for Medicare & Medicaid Services. CMS Finalizes New Medicare Card Distribution Ahead of Deadline, Accelerating Fight Against Medicare Fraud and Abuse
Why Medicare Made the Switch
For decades, Medicare’s claim number was built around the beneficiary’s Social Security Number, so every card handed to a doctor’s office, pharmacy, or hospital displayed the SSN. A lost wallet could expose the cardholder to identity theft that went well beyond Medicare fraud. MACRA directed CMS to replace that identifier with one that contains no personal information.
The change was about security only. Getting a new card and MBI did not alter anyone’s Medicare benefits or coverage.2Centers for Medicare & Medicaid Services. CMS Reveals New Medicare Card Design
What the MBI Looks Like
The MBI is an 11-character code made up of numbers and uppercase letters. It is randomly generated, and CMS calls the characters “non-intelligent” because no part of the code reveals your SSN, date of birth, or any other personal detail.3CMS. Understanding the Medicare Beneficiary Identifier (MBI) Format
To keep it readable, CMS excluded six letters that look too much like numbers: S, L, O, I, B, and Z. The remaining letters and digits sit in a fixed pattern where certain positions are always letters, others are always numbers, and some can be either. That structure lets providers catch typos quickly during data entry.4Centers for Medicare & Medicaid Services. Understanding the Medicare Beneficiary Identifier (MBI) Format
The redesigned card keeps the familiar red, white, and blue color scheme. The MBI appears where the old HICN used to be, and your Social Security Number is nowhere on the card. Your name is printed as Social Security has it on file, along with the effective dates for your Part A and Part B coverage.
What to Do If You Still Have the Old Card
If you never received or never activated the new card, the old HICN no longer works for billing. You’ll need to get a card with your MBI before your next appointment.
The fastest option is to sign in at Medicare.gov and print an official copy right away. You can order a physical replacement through the same account. If you don’t already have an online account, you can create one using ID.me, Login.gov, or CLEAR for identity verification.5Medicare. Your Medicare Card
You can also call 1-800-MEDICARE (1-800-633-4227) to have one mailed. TTY users can call 1-877-486-2048. Railroad Retirement Board beneficiaries should call 1-877-772-5772 instead.5Medicare. Your Medicare Card
Once your new card is in hand, CMS recommends destroying the old one so nobody can pull your SSN off it. Mailed replacements generally take about 30 days to arrive, so the printable copy from your Medicare.gov account is worth having in the meantime.
Watch for Scams Using the “New Card” Angle
The switch to the MBI has been over for years, but scammers still call beneficiaries claiming they need a new plastic Medicare card, a card with a chip, or an updated card for the new year. None of that is real. Medicare has no plans to issue another new card, and the legitimate Medicare card is paper.
The Federal Trade Commission warns that Medicare will never call to ask for personal information to issue a card, and there is no fee for your card. If someone asks you to pay or to “verify” your Medicare number over the phone, hang up.6Federal Trade Commission. Hang Up on Medicare Card Scams
Treat your MBI the way you would a credit card number. If you think it has been stolen or misused, call 1-800-MEDICARE. CMS can issue you a new MBI and mail a replacement card, which the agency has done on a large scale in response to data breaches involving beneficiary information.7Centers for Medicare & Medicaid Services. CMS Notifies Individuals Potentially Impacted by Data Incident After a new MBI is issued, share it with every provider, pharmacy, and supplemental insurer you use, because claims under the old number will be rejected.