Social Security Number (SSN)

Social Security Numbers consist of nine digits (000-00-0000). The first three digits are the Area Number.  The middle two digits are the Group Number. The last four digits are the Serial Number.

Area Numbers are assigned to geographical locations, except 700-729 which was assigned to railroad workers.

Group Numbers are assigned by the order in which SSNs are issued for a particular area.

Serial Numbers are assigned in chronological order.

Prior to 1972, Social Security cards were issued in local Social Security offices around the country. After 1972, the Social Security Administration began issuing Social Security Numbers centrally from Baltimore, MD USA. Thus, the Area Number does not necessarily represent the State of residence of the applicant.

Since October 30, 1983, all Social Security cards issue new or as replacement cards are now made of banknote paper to prevent counterfeiting.

The Social Security Administration (SSA) is changing the way Social Security Numbers (SSNs) are issued. This change is referred to as "randomization." The SSA is developing this new method to help protect the integrity of the SSN. SSN Randomization will also extend the longevity of the nine-digit SSN nationwide.

The SSA began assigning the nine-digit SSN in 1936 for the purpose of tracking workers' earnings over the course of their lifetimes to pay benefits. Since its inception, the SSN has always been comprised of the three-digit area number, followed by the two-digit group number, and ending with the four-digit serial number. Since 1972, the SSA has issued Social Security cards centrally and the area number reflects the state, as determined by the ZIP code in the mailing address of the application.

There are currently 435 million numbers available for assignment. However, the current SSN assignment process limits the number of SSNs that are available for issuance to individuals by each state. Changing the assignment methodology will extend the longevity of the nine digit SSN in all states. On July 3, 2007, the SSA published its intent to randomize the nine-digit SSN in the Federal Register Notice, Protecting the Integrity of Social Security Numbers [Docket No. SSA 2007-0046].

SSN randomization will affect the SSN assignment process in the following ways:

• It will eliminate the geographical significance of the first three digits of the SSN, currently referred to as the area number, by no longer allocating the area numbers for assignment to individuals in specific states.
• It will eliminate the significance of the highest group number and, as a result, the High Group List will be frozen in time and can be used for validation of SSNs issued prior to the randomization implementation date.
• Previously unassigned area numbers will be introduced for assignment excluding area numbers 000, 666 and 900-999.

These changes to the SSN may require systems and/or business process updates to accommodate SSN randomization.

Social Security Number Numbering Scheme.

Social Security Number Verification Service (SSNVS).