Internal Revenue Service United States Department of the Treasury


Social Security Numbers are nine digit numbers composed of three parts:

  • - Area Number, the first set of three digits;
  • - Group Number, the second set of two digits;
  • - Serial Number, the final set of four digits.

Area Number

The Area Number is assigned by geographical region. Before 1972, the Area Number represented the State where the card was issued. A person could apply for their card in any Social Security office in the United States. Therefore, the Area Number did not necessarily represent the state of residence. After 1972, the area number is based on the ZIP code given as the applicant's mailing address for the original Social Security card. The mailing address may be different from the applicant's place of residence. The Area Number may or may not represent the State of residence for the applicant.

Numbers were assigned beginning in the northeast and moved westward. For this reason, people in the east have lower area numbers than people in the west.

The numbering scheme was designed in 1936 as a bookkeeping device for our own internal use and was never intended to be anything more than that.

Group Number

Within each area, the group number (middle two (2) digits) range from 01 to 99 but are not assigned in consecutive order. For administrative reasons, group numbers issued first consist of the ODD numbers from 01 through 09 and then EVEN numbers from 10 through 98, within each area number allocated to a State. After all numbers in group 98 of a particular area have been issued, the EVEN Groups 02 through 08 are used, followed by ODD Groups 11 through 99.Group numbers are assigned as follows:
ODD - 01, 03, 05, 07, 09------EVEN - 10 to 98
EVEN - 02, 04, 06, 08------ODD - 11 to 99

Serial Number

Within each group, the serial numbers (last four (4) digits) run consecutively from 0001 through 9999.


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