What is a Social Security Number?

Updated on January 8, 2023

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Social Security Number definition and meaning

A social security number is a unique, nine-digit number that serves as an individual’s continuous connection with Social Security. The SSA uses this number to track any taxable income earned by US citizens, whether from an employer, or through self-employment, to identify eligibility for, issue the payment of, and monitor the record for Social Security benefits.


More about Social Security Numbers

The Social Security Card issued by the SSA should be stored in a safe place, and generally not kept on your person. This card, and its number are important because you need them to be hired to work in the US. Sometimes, new employment includes the photocopying of the new employee’s Social Security Card, to be kept on file by the employer, but usually just knowing your number and providing other forms of ID are enough.


Using Social Security Number in a sentence

“It’s a good idea to memorize your social security number, because you never know when you’ll need to use it to verify your identity.”

Terms related to Social Security Number (SSN)

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