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What is My Medicare Beneficiary Identification Number?

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Just the Essentials...

  • Your Medicare Beneficiary Identification number (MBI) can be found on your red, white, and blue Medicare card

  • Formerly, the MBI was the Medicare Claim Number, but it contained a beneficiary’s Social Security number. For identity protection, the MBI replaces it.

  • Due to the sensitive nature of your Medicare number, it can be looked up online after making an account with “my Social Security“.

  • If you lose your Medicare card with your number on it, you can request that the Social Security Administration replace your card at no charge

  • The Medicare Beneficiary Identifier is for claims, billing and identification purposes

What is my Medicare provider identification number?

What Is My Medicare Beneficiary Identification Number?

Your  Medicare Beneficiary Identifier (MBI) number is for billing and identification purposes.

On a Medicare card received before 2015, your Medicare Claim Number consisted of your Social Security number (SSN) followed by a code of letters and sometimes numbers that have a specific meaning.

In more recent years, a randomly-generated combination of letters and numbers replaced this Medicare Claim number.

Removing Social Security numbers from Medicare cards further protects the identities of Medicare beneficiaries from identity theft. The replacement number is called the Medicare Beneficiary Identifier, or MBI number.

Moreover, if you still have a Medicare card with your Social Security number on it, you can still use it. Nonetheless, getting a new Medicare card is certainly in your best interest.

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What do the codes following my Social Security number mean?

What is my Medicare provider identification number?

Some people still keep and use the original copy of their red, white, and blue Medicare card containing their Social Security number.

After the Social Security number, there is a letter and sometimes a number.  These codes all have different meanings.

The most common letters to find on your card following your Social Security number are A and B.

If you have an A on your card, it means that you are the primary beneficiary. That means you earned Medicare insurance based on your working history and tax credits.

If you have a B following your Social Security number, you are registered with Medicare as the spouse of a retired worker who earned Medicare.

There are several variations to the B code:

  • B1 is for a husband of a primary beneficiary at age 62 or over.
  • B2 is for a young wife with a child in her care,
  • B3 is for an aged wife over the age of 62 who is a second claimant
  • B5 is also a second claimant wife, but they are under the age of 62 and have a child in their care.
  • B6 represents a divorced wife over the age of 62
  • BY is for a young husband with a child in his care.


Additionally, Codes C1-C9 represent children who may be minors, students, or disabled.

The letter “D” follows for aged widows over the age of 60 or a surviving divorced wife over the age of 60.

The letter “E” code is for a widowed mother, while E1 is a surviving divorced mother.

E4 is a widowed father, and E5 is a surviving divorced father.

The letter “F” codes are for parents.

“T” code is for those who are enrolled in Medicare but are being temporarily delayed their Social Security Benefits or are uninsured.

”TA” is for Medicare qualified government employees. ‘

‘W’‘ is for a disabled widow, and ‘‘WA’‘ is for railroad retirement.

Where is this number located?

What is my Medicare provider identification number? - Social Security

This number is located on your Medicare card. It is also on most of the documentation you receive from Medicare or the Social Security Administration.

Alternatively, you can also visit your local Social Security Administration office or call Social Security to get your number.

If you are automatically enrolled in Medicare, you will receive your card in the mail three months before your 65th birthday or before the 25th month you receive your disability benefits.

There is additional important information located on your Medicare card for you and your doctor.

This includes your name and sex (but not your date of birth). Additionally, it states whether you have Medicare Part A (inpatient hospital) and Medicare Part B (outpatient medical), and lists the dates that Part A and B first started.

Lastly, sign your Medicare card prior to use.

What do I do if I lose my Medicare card with my number on it?

What is my Medicare provider identification number?

If damaged, lost or stolen, you can request a new Medicare card (complete with a new Medicare Beneficiary Identifier number) from Social Security.

After your replacement request, the card typically arrives in the mail in about 30 days, at no cost to the beneficiary.

Social Security will mail your Medicare card to the address they have on file for you, so it is important to keep your information with them up to date.

You can update your address online using your ”my Social Security” account.

If you need proof of your Medicare insurance sooner than the 30 days, Social Security can send you a letter stating your insurance status within 10 days.

Alternatively, you can get proof immediately by visiting your local Social Security office.

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