Your Medicare ID number is the 11-character Medicare Beneficiary Identifier (MBI) printed on the front of your red, white, and blue Medicare card. It’s the code providers, pharmacies, and plans use to confirm your coverage and bill for your care. If you don’t have the card in front of you, you can also pull the number from your account at Medicare.gov or from a Social Security benefit verification letter.
What the Number Looks Like
The MBI is 11 characters long and mixes digits with uppercase letters in a fixed pattern. Positions 1, 4, 7, 10, and 11 are always numbers. Positions 2, 5, 8, and 9 are always letters. Positions 3 and 6 can be either. Six letters never appear at all (S, L, O, I, B, and Z) because they’re easy to confuse with numbers.1CMS. Understanding the Medicare Beneficiary Identifier (MBI) Format A sample MBI looks like 1EG4-TE5-MK72. The dashes are just spacing to make the code easier to read, and the characters themselves are randomly generated with no hidden meaning.
The MBI replaced the older Health Insurance Claim Number, which was built from a beneficiary’s or spouse’s Social Security Number. All Medicare billing and eligibility now runs on the MBI exclusively.2Centers for Medicare & Medicaid Services (CMS). We’re Using Medicare Beneficiary Identifiers (MBIs)
Where to Find Your Medicare ID Number
The most direct source is the physical Medicare card mailed to you when you enrolled. Along with the MBI, the card lists whether you have Part A (labeled “Hospital”), Part B (labeled “Medical”), or both, and the date each part started.3Medicare. Your Medicare Card
If the card isn’t handy, sign into your account at Medicare.gov to view or print an official copy. Creating the account the first time requires your MBI and coverage start date from the card itself, so set it up while you still have the card in hand.4Medicare. Create an Account Once the account exists, you can pull the card up from a phone or computer anytime.5Medicare. Go Digital
Your MBI also appears on the benefit verification letter you can download from your Social Security account at SSA.gov.6Social Security Administration. Manage Your Medicare Benefits
If You Arrive at a Doctor’s Office Without the Card
Providers can look your MBI up through a secure Medicare portal using your first name, last name, date of birth, and Social Security Number.7Centers for Medicare & Medicaid Services (CMS). Getting MBIs If you’d rather not share your SSN at the desk, the office can point you to Medicare.gov to retrieve the number yourself. Either way, forgetting the card doesn’t have to mean canceling the appointment.
When the Medicare Card Is the Right Card to Show
Bring the red, white, and blue Medicare card to doctor’s visits, hospital stays, and outpatient procedures under Original Medicare. Providers use the MBI to verify eligibility and submit claims.2Centers for Medicare & Medicaid Services (CMS). We’re Using Medicare Beneficiary Identifiers (MBIs) You’ll also need the number when you change plans or call Medicare about your coverage.
A common source of confusion: your Medicare card isn’t always the card to hand over. It depends on how you get your coverage.
- With Original Medicare only, use the Medicare card for all covered services. Part B covers drugs given in a medical setting, such as infusions, injections, and certain vaccines, but not most prescriptions filled at a pharmacy.8Medicare. Prescription Drugs (Outpatient)
- With a stand-alone Part D drug plan, use the plan’s own membership card at the pharmacy, not the Medicare card.9Centers for Medicare & Medicaid Services. Your Guide to Medicare Drug Coverage
- With a Medicare Advantage (Part C) plan, use the Advantage plan’s card for healthcare services and for prescriptions if the plan includes drug coverage. Keep the original Medicare card safe, because you’ll need the MBI if you switch plans or are admitted to a hospital.2Centers for Medicare & Medicaid Services (CMS). We’re Using Medicare Beneficiary Identifiers (MBIs)
Even when you rarely show the Medicare card day to day, your MBI is what a Medicare Advantage, Part D, or Medigap plan uses to confirm your underlying Medicare eligibility.
Replacing a Lost or Stolen Card
The fastest replacement is through your Medicare.gov account, where you can print an official copy of your card immediately and order a physical replacement.3Medicare. Your Medicare Card To order by phone, call 1-800-MEDICARE (1-800-633-4227). TTY users can call 1-877-486-2048.
Social Security does not issue replacement Medicare cards. A call to SSA about a lost card will send you back to Medicare.gov or 1-800-MEDICARE.10Social Security Administration. How Do I Get a Replacement Medicare Card?
While you wait, an SSA benefit verification letter works as proof of Medicare coverage. You can download it after signing into SSA.gov or by calling Social Security at 1-800-772-1213.11Social Security Administration. How Can I Get a Benefit Verification Letter?
Protecting Your Medicare Number
Medicare classifies the MBI as personally identifiable information, on par with your Social Security Number.2Centers for Medicare & Medicaid Services (CMS). We’re Using Medicare Beneficiary Identifiers (MBIs) Share it only with healthcare providers, pharmacists, and insurers actively handling your care.
A frequent scam involves a caller claiming to be “from Medicare” and demanding you verify your number or lose your benefits. Medicare doesn’t operate that way. If you get that call, hang up. To report suspected fraud, call 1-800-MEDICARE or file a report through the Office of Inspector General at oig.hhs.gov. If you have a Medicare Advantage or Part D plan, you can also call the Investigations Medicare Drug Integrity Contractor at 1-877-772-3379.12Medicare. Reporting Medicare Fraud and Abuse
Getting a New MBI After Identity Theft
If your MBI has been compromised, call 1-800-MEDICARE to request a new one. TTY users can call 1-877-486-2048. CMS handles all MBI change requests and can also initiate a change in limited situations, such as a court order.13Social Security Administration. New Medicare Numbers and Number Change Requests Once the new number is issued, the old one stops working and a new card is mailed to you.
Railroad Retirement Board Beneficiaries
If you get benefits through the Railroad Retirement Board, your Medicare card is a little different. It reads “Railroad Retirement Board” at the bottom and the number is formatted as four digits, a dash, three digits, a dash, four digits.14RRB.Gov. Sample Medicare Card The card still shows your Part A and Part B coverage dates and you use it the same way as any other Medicare card. For a replacement, contact the RRB directly rather than Medicare.gov, since your enrollment is administered through the railroad retirement system.