How to find your Medicare number (MBI)
Find your Medicare number (MBI) on your red, white and blue card, at Medicare.gov, through Social Security, or on your Medicare Summary Notice.
(updated ) · Khoi Le · Doodle
The short answer
Your Medicare number is the same thing as your Medicare Beneficiary Identifier (MBI). It is the 11-character ID on the front of your red, white, and blue Medicare card. It is not your Social Security number.
| Where to look | What you get | Best if… |
|---|---|---|
| Medicare card | Medicare Number on the front | You have the card with you |
| Medicare.gov account | View or print an official copy of your card | You can sign in (or already have an account) |
| Social Security account | Medicare Number on your benefit verification letter | You do not have the card yet, or Medicare.gov signup is asking for the number |
| Medicare Summary Notice (MSN) | Medicare Number on the notice | You get quarterly claims mail, or you can view notices in Medicare.gov |
| 1-800-MEDICARE | Help finding the number, or a mailed replacement card | You prefer the phone |
Open 24 hours a day, 7 days a week: 1-800-MEDICARE (1-800-633-4227). TTY: 1-877-486-2048.
How to find your Medicare number without your card
Use the paths below if your card is lost, damaged, or not with you. Keep your red, white, and blue card in a safe place even if you have a Medicare Advantage or Part D plan card.
1. On your Medicare card
The red, white, and blue card lists your Medicare Number on the front. That is your MBI. CMS calls it the MBI. The card calls it the Medicare Number. They are the same.
2. In your Social Security account
SSA.gov says you can find your Medicare number by signing in to your Social Security account and viewing your benefit verification letter.
- Go to SSA.gov and sign in to your personal my Social Security account, or create one.
- Choose Get a Benefit Verification Letter.
- Find your Medicare Number on the letter.
This is a strong option if you do not have your card, because creating a Medicare.gov account can ask for the Medicare Number.
The account has to be your own. If you are helping a parent, they sign in or sign up themselves. You can sit with them while they do.
3. In your Medicare.gov account
- Go to Medicare.gov and sign in. Older MyMedicare.gov bookmarks go there too.
- Open the page for your Medicare card. Medicare.gov labels it Print My Medicare Card or Get my Medicare card.
- Read the Medicare Number on that copy.
You can also order a replacement card to be mailed from the same account.
4. On your Medicare Summary Notice (MSN)
Your Medicare Summary Notice is the quarterly claims summary Medicare mails for Original Medicare Part A and Part B services (or that you can view after signing in at Medicare.gov). Official CMS sample notices print your Medicare Number near the top of the notice.
- Check recent mail for an MSN, or sign in at Medicare.gov and open your claims / MSN notices.
- Look for Medicare Number on the notice header.
- Use that number the same way you would use the number on your card.
If you only see the last few characters in a “check your information” box, look at the full number printed elsewhere on the same notice (CMS samples show the full Medicare Number on the notice itself).
5. By calling 1-800-MEDICARE
Call 1-800-MEDICARE (1-800-633-4227). TTY: 1-877-486-2048. Ask for help finding your Medicare Number, or ask them to mail you a replacement card.
If you get Railroad Retirement Board (RRB) benefits, Medicare.gov says to call 1-877-772-5772 for a replacement card. TTY: 1-312-751-4701.
What your Medicare number (MBI) looks like
CMS gives every person with Medicare an MBI. It replaced the older number that was based on your Social Security number.
| Fact | Detail |
|---|---|
| Length | 11 characters |
| Characters | Uppercase letters and numbers |
| Meaning | Randomly assigned — no SSN or “code” inside it |
| Hyphens | May appear on the card for readability; leave them out when you type |
| Letters never used | S, L, O, I, B, Z (they look too much like numbers) |
If you have Medicare Advantage or Part D
If you joined a Medicare Advantage (Part C) or Part D drug plan, you usually show that plan’s card for care and pharmacy visits. Your red, white, and blue Medicare card is still yours — keep it. You may still need the Medicare Number (MBI) to:
- Set up or use a Medicare.gov account
- Talk with a licensed agent you contacted
- Enroll in or change certain coverage
- Handle Original Medicare claims or paperwork
Keep it safe
Treat your Medicare Number the way you would treat a credit card number. Give it to your doctor or hospital, your health plan, a licensed agent or broker you chose to talk with, or your State Health Insurance Assistance Program (SHIP) counselor. Do not give it to someone who contacted you first and asked for it.
Medicare.gov says Medicare will never call you uninvited and ask for personal or private information. If someone does, hang up and call 1-800-MEDICARE.
If you think someone is misusing your number, call 1-800-MEDICARE. CMS says you can ask to have your MBI changed if it was compromised.
When you might need it
You may be asked for your Medicare Number when you:
- See a doctor or hospital under Original Medicare
- Join a Medicare health plan, a Medicare drug plan, or a Medigap policy
- Talk with a licensed agent you contacted
- Set up a Medicare.gov account
- Need a replacement card
Common questions
Is the MBI the same as a Social Security number?
No. Your MBI is 11 letters and numbers. A Social Security number is 9 digits. Medicare stopped printing Social Security numbers on Medicare cards.
What if I lost my Medicare card?
Sign in to Medicare.gov to print a copy or order a mailed replacement, call 1-800-MEDICARE, check your Social Security benefit verification letter, or look for the Medicare Number on a recent Medicare Summary Notice.
Can I look up a parent’s Medicare number for them?
Only together with them. Their SSA.gov and Medicare.gov accounts have to be their own. Sit with them while they sign in, or call 1-800-MEDICARE together.
Can Doodle look it up for me?
No. We do not collect your Medicare Number on this site. If you want help with a Medicare question, you can start a conversation with us.
What does MBI stand for?
Medicare Beneficiary Identifier. On your card and in most everyday talk, it is simply your Medicare number.
About this page
Written for Doodle by Khoi Le. Reviewed against Medicare.gov, SSA.gov, and CMS public materials on September 26, 2026.
This page is educational. It is not advice, a quote, or an invitation to enroll.
Sources
- Your Medicare card (Medicare.gov)
- Manage your Medicare benefits (SSA.gov)
- How to get Medicare services (Medicare.gov)
- Medicare Beneficiary Identifiers (MBIs) (CMS)
- Sample Medicare Summary Notice (Part B) (Medicare.gov)