What does the red number on the back of a Social Security card mean? According to a presentation given by Donald F. Walton, United States Trustee for Region 21 (Georgia, Florida, Puerto Rico, and the US Virgin Islands) to a meeting of the American Bankruptcy Institute in April 2009, the number printed on the back of the card is a " sequential control number ." These alpha-numeric codes are printed in red, black or blue ink and help authenticate the card as valid. This information was shared in the context of Bankruptcy Courts checking Social Security cards through the Social Security Administration, to prevent identity theft. The sequential control number, which bears no obvious correlation to an individual's Social Security Number should correspond to the date, area, and application of a particular cardholder. According to Mr. Walton: "Sequential Control Number. On the rear of a legitimate card there is a sequential control number. The control number is a combination of alpha and numeric that bears no relation to the actual. social security number on the card. However, the computer records of the Social Security Administration should show a correlation between the control number and the social security number and name on the card." One blog commenter noted that she and her husband had applied for duplicate cards at approximately the same time, and that their sequential control numbers were identical except for the last two digits. This tends to support the idea that the numbers are generated at the printer