What does the letter after my Medicare number mean?

March 2018 Update - Medicare Cards are Changing - New Card, Same Benefits
The Centers for Medicare and Medicaid Services (CMS) is mailing new Medicare cards starting April 2018 and continuing through April 2019. As noted by CMS, "[t]he new cards will use a unique, randomly-assigned 11-digit number called a Medicare Beneficiary Identifier (MBI), to replace the Social Security-based Health Insurance Claim Number (HICN) currently used on the Medicare card." CMS also noted that this initiative "will prevent fraud, fight identity theft and protect essential program funding and the private healthcare and financial information of our Medicare beneficiaries." To learn more about the new Medicare cards, please click on the following link for our FAQ: "What do we need to know about the new Medicare cards?" on this site

Original text of:
"What does the letter after my Medicare number mean?"

We have been getting more questions from people asking what the letters mean in their Medicare Claim Number. Here is an explanation and chart of the letter meaning provided by the Social Security Administration:

The Social Security number followed by one of these codes is often referred to as a claim number. Social Security assigns these codes once you apply for benefits. These letter codes may appear on correspondence you receive from Social Security or on your Medicare card. They will never appear on a Social Security card.

For example, if the wage earner applying for benefits and your number is 123-45-6789, then your claim number is 123-45-6789A. This number will also be used as your Medicare claim number, once you are eligible for Medicare.

Code	Identification
A	Primary claimant (wage earner) - the most common code
B	Spouse, Aged wife, age 62 or over
B1	Aged husband, age 62 or over
B2	Young wife, with a child in her care
B3	Aged wife, age 62 or over, second claimant
B5	Young wife, with a child in her care, second claimant
B6	Divorced wife, age 62 or over
BY	Young husband, with a child in his care
C1-C9	Child - Includes minor, student or disabled child
D	Aged Widow, age 60 or over
D1	Aged widower, age 60 or over
D2	Aged widow (2nd claimant)
D3	Aged widower (2nd claimant)
D6	Surviving Divorced Wife, age 60 or over
E	Widowed Mother
E1	Surviving Divorced Mother
E4	Widowed Father
E5	Surviving Divorced Father
F1	Parent (Father)
F2	Parent (Mother)
F3	Stepfather
F4	Stepmother
F5	Adopting Father
F6	Adopting Mother
HA	Disabled claimant (wage earner)
HB	Aged wife of disabled claimant, age 62 or over
M	Uninsured – Premium Health Insurance Benefits (Part A)
M1	Uninsured - Qualified for but refused Health Insurance Benefits (Part A)
T	Uninsured - Entitled to Health Insurance Benefits HIB (Medicare Part A) under deemed or renal provisions; or Fully insured who have elected entitlement only to Health Insurance Benefits (Medicare Part A) - (and not yet entitled to retirement benefits - entitled to Medicare but not yet drawing Social Security Benefits)
TA	Medicare Qualified Government Employment (MQGE)
TB	MQGE aged spouse
W	Disabled Widow
W1	Disabled Widower
W6	Disabled Surviving Divorced Wife

NOTE: This list is not complete, but shows the most common beneficiary codes.