Decode the Meaning of Social Security Numbers

Decoding Social Security Numbers is easier than most people realize. Social Security Numbers are broken into three parts: area, group and series.

Look up SSNs By State and Year

Social Security Cards showing the parts of an SSN.
Dummy Social Security Card showing the parts of a Social Security Number.

In a Social Security Number, the first three digits are called the "area." The forth and fifth digits are called the "group." Finally, the last four digits are called the "series." Here is the explanation of what each piece means:

Area - 123-45-6789

The first 3 digits of an SSN represent where a Social Security Number was issued. In some cases, the "area" represents a group of people or demographic that is not directly tied to a geographic location.

Most SSNs were split into groups and assigned to different states. The large states got larger blocks of numbers.

SSNs ranging from 900-##-#### to 999-##-#### were designated at Individual Taxpayer Identification Numbers (What is an ITIN?) and given to people who have tax obligations but do not qualify of a Social Security Number.

Other blocks of SSNs were reserved for the minor outlying islands of the united states and for enumeration at entry which are given out when people immigrate to the US.

Group - 123-45-6789

The fourth and fifth digits of a Social Security Number is called the "group." Within each "area" block, SSNs where issued semi-consecutively by group. First groups issued are odd groups from 00 to 09, then even groups from 10 to 98, followed by even groups from 02 to 08, and finally odd groups from 11 to 99.

We know approximately when each group was first use so we can figure out when any Social Security Number was issued.

You can use the SSN Search Tool to see the issuance year for any SSN.

Series - 123-45-6789

"Series" is the last 4 digits of a social security and is used to ensure no two people have the same Social. Within each "group," series numbers are issued consecutively from 0001 to 9999 (SSNs ending in 0000 are invalid).

Limitations to Decoding SSNs

SSN Randomization took place in June 2011 and was when the Social Security Administration the practice of issuing Socials in defined pattern. After June 2011, all SSNs are issued in randomized order meaning the patterns outlined above and all SSN Tools on this site no longer apply.

Despite these limitations, most Social Security Numbers in circulation today follow the pattern above. Now that we have explained how Social Security Numbers work, it is easy to guess many social security numbers.

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