What is the number on the back of my social security card for?

There's no need to contact anyone about the sequential control number on the back of your card. The only purpose it serves is to help the Social Security Administration determine whether a card is authentic or fraudulent, based on the combined match between your name, social security number, date and location of printing and distribution, card application. The number is being used to combat identity theft, and serve no other purpose.

For more information, see Related Questions, below.