The codes following a Social Security number indicate the type of benefits you are entitled to. The Social Security number followed by one of these codes is often referred to as a claim number and they are only assigned once you apply for benefits. These letter codes may appear on correspondence that you receive from Social Security or on your Medicare card. They will never appear on a Social Security number card.

For example, if the Social Security of the wage earner number is 123-45-6789, then once you apply for retirement benefits, your claim number is 123-45-6789A (A - Primary claimant or wage earner). This number and letter will also be used as your Medicare claim number, once you are eligible for Medicare.