# US Social Security Number

Key: `identity.government.ssn`

9-digit identifier assigned to US citizens and residents for tax and social security purposes. Format: AAA-GG-SSSS where area number cannot be 000, 666, or 900-999.

Page: <https://meridian.online/docs/projects/finetype/types/identity/government/ssn>

Samples: `078-05-1120`, `219-09-9999`, `123-45-6789`, `531-02-7834`

## Background

### Origin

Social Security numbers were first issued by the Social Security Administration in November 1936, as part of the New Deal Social Security programme.[[1]](https://en.wikipedia.org/wiki/Social_Security_number) Within three months, 25 million numbers were issued.[[1]](https://en.wikipedia.org/wiki/Social_Security_number) The original purpose of the Social Security number was to track individuals' accounts within the Social Security programme.[[1]](https://en.wikipedia.org/wiki/Social_Security_number) It has since come to be used as an identifier for individuals within the United States.[[1]](https://en.wikipedia.org/wiki/Social_Security_number)

The Social Security number is a nine-digit number in the format AAA-GG-SSSS.[[1]](https://en.wikipedia.org/wiki/Social_Security_number) The first three digits are called the area number, because they were formerly assigned by geographical region.[[1]](https://en.wikipedia.org/wiki/Social_Security_number)

On June 25, 2011, the Social Security Administration changed its assignment process to what it calls SSN randomization.[[1]](https://en.wikipedia.org/wiki/Social_Security_number) Randomization eliminated the geographical significance of the area number.[[1]](https://en.wikipedia.org/wiki/Social_Security_number) It also introduced previously unassigned area numbers for assignment, excluding area numbers 000, 666 and 900–999.[[1]](https://en.wikipedia.org/wiki/Social_Security_number)

### Use

A Social Security number is issued by the Social Security Administration, whereas all other US taxpayer identification numbers are issued by the IRS.[[2]](https://www.irs.gov/tin/taxpayer-identification-numbers-tin) The IRS's Individual Taxpayer Identification Number, or ITIN, is a 9-digit number beginning with 9 and formatted like an SSN (NNN-NN-NNNN).[[2]](https://www.irs.gov/tin/taxpayer-identification-numbers-tin) If values in a column start with 9, check whether it holds ITINs, or a mix of ITINs and SSNs, before you label it. (Meridian's view)

Numbers with 666 or 900–999 in the first digit group are never allocated.[[1]](https://en.wikipedia.org/wiki/Social_Security_number) A pattern check can therefore only rule a value out; it cannot tell a genuine SSN from a well-formed invented one. (Meridian's view) Now that numbers are assigned randomly, fraudulent SSNs are not easily detectable with publicly available information.[[1]](https://en.wikipedia.org/wiki/Social_Security_number)

### Where you'll meet it

The IRS lists the SSN among the taxpayer identification numbers that must be furnished on returns, statements and other tax-related documents.[[2]](https://www.irs.gov/tin/taxpayer-identification-numbers-tin)

The National Personnel Records Center asks that every request for a veteran's records include the veteran's Social Security number.[[3]](https://www.archives.gov/personnel-records-center/social-security-numbers) The Army and Air Force stopped using the service number as an identifier and began using the Social Security number on July 1, 1969.[[3]](https://www.archives.gov/personnel-records-center/social-security-numbers) The Navy and Marine Corps changed over on January 1, 1972.[[3]](https://www.archives.gov/personnel-records-center/social-security-numbers) The Coast Guard changed over on October 1, 1974.[[3]](https://www.archives.gov/personnel-records-center/social-security-numbers)

## Sources

1. [Social Security number - Wikipedia](https://en.wikipedia.org/wiki/Social_Security_number) — secondary source
2. [Taxpayer identification numbers (TIN) \| Internal Revenue Service](https://www.irs.gov/tin/taxpayer-identification-numbers-tin) — organisation
3. [Service Numbers and Social Security Numbers \| National Archives](https://www.archives.gov/personnel-records-center/social-security-numbers) — organisation