Your Medicare claim number is the Medicare Beneficiary Identifier, or MBI: an 11-character code of numbers and uppercase letters printed on your red, white, and blue Medicare card, directly beneath your name and labeled “Medicare Number.” It’s the identifier providers use to bill Medicare and the number you’ll give any time Medicare asks who you are.
Where to Find Your Medicare Number
Look at your Medicare card first. The MBI sits under your name on the front of the card. If you can’t put your hands on the card, you have three quick ways to pull the number:
- Log in at Medicare.gov and view your MBI in your account. This is the fastest option.
- Sign in to your my Social Security account at SSA.gov and open your benefit verification letter, which lists your Medicare number.1Social Security Administration. Manage Your Medicare Benefits
- Call 1-800-MEDICARE (1-800-633-4227). TTY users can reach the same line at 1-877-486-2048.
To request a physical replacement card, use your Medicare.gov account or call 1-800-MEDICARE.
What the MBI Looks Like
The MBI is 11 characters, mixing digits and uppercase letters, randomly generated with no personal information built in. Spouses each get completely different numbers.2Centers for Medicare & Medicaid Services. Understanding the Medicare Beneficiary Identifier (MBI) Format To avoid character confusion, the MBI never uses the letters S, L, O, I, B, or Z. If you think you see one of those on your card, you’re reading a similar-looking number or another character.3Centers for Medicare & Medicaid Services. We’re Using Medicare Beneficiary Identifiers (MBIs)
If You Still Have an Old Card
Before 2018, the Medicare claim number was called the Health Insurance Claim Number, or HICN. It was your nine-digit Social Security number followed by a one- or two-character suffix.4CMS. Social Security Number Removal Initiative SSNRI Open Door Forum Congress ordered that number off Medicare cards in 2015 to cut identity theft risk, and CMS replaced every card with the new MBI format.5Centers for Medicare & Medicaid Services. Medicare Access and CHIP Reauthorization Act Since January 1, 2020, the MBI has been required for essentially all Medicare transactions.3Centers for Medicare & Medicaid Services. We’re Using Medicare Beneficiary Identifiers (MBIs) If the number on your card still looks like a Social Security number with a letter tacked on, that card is outdated and won’t work for claims. Request a replacement through Medicare.gov or 1-800-MEDICARE.
Which Card to Show If You Have Medicare Advantage or Part D
Enrolling in a Medicare Advantage plan (Part C) or a standalone Part D drug plan means you also received a separate card from that plan. For most services, show the plan’s card, not your original Medicare card, because the plan handles billing through its own systems and needs its member ID.6Medicare. Your Medicare Card Hospice care and some other services may still require the red, white, and blue Medicare card with your MBI. Keep the original card either way; you’ll need it if you switch back to Original Medicare.
Railroad Retirement Board Cards
If you get Medicare through the Railroad Retirement Board, your card says “Railroad Retirement Board” at the bottom. The number on it is still an MBI in the same format and you use it the same way. For help with a Railroad Medicare card, contact the RRB directly rather than the Social Security Administration.
Protecting Your Number
Treat your MBI like a credit card number. Share it only with healthcare providers you’re actually seeing, your Medicare plan, or Medicare itself. It no longer contains your Social Security number, but a stolen MBI can still be used to file fraudulent claims in your name.
Scammers regularly call or mail Medicare beneficiaries claiming you need to “activate,” “renew,” or “upgrade” your card, or asking for your number to “verify” your account. These are scams. Medicare will not call you out of the blue asking for personal information, and there is no activation fee and no renewal process for a Medicare card.7Medicare.gov. Reporting Medicare Fraud and Abuse If a caller asks for your Medicare number, hang up. Review your Medicare Summary Notices for services you don’t recognize.
Replacing an MBI After Suspected Theft
You can’t cancel an MBI on the spot the way you would a credit card, but CMS will issue a replacement if you have reason to believe yours has been compromised. Call 1-800-MEDICARE (TTY: 1-877-486-2048) and explain the situation. CMS handles Medicare number change requests and will permit a new MBI when a beneficiary reports suspected compromise.8Social Security Administration. New Medicare Numbers and Number Change Requests Confirm your mailing address is current so the new card reaches you. Once the replacement is issued, the old number stops working for claims, so tell your providers to update their billing records.