How Many Numbers Does a Social Security Number Have?

A Social Security number has nine digits, written in the pattern XXX-XX-XXXX: three digits, a hyphen, two digits, another hyphen, and four digits. The hyphens are visual separators that appear on the card and on most forms, but only the nine digits themselves matter for identification.1Social Security Administration. Social Security History – The SSN Numbering Scheme

What the Three Segments Are Called

Each of the three groups of digits has a name and a historical role. The structure has stayed the same since the program began.

  • The first three digits are the area number. They originally indicated the state or region where you applied for your card.
  • The middle two digits are the group number. They ran from 01 to 99 and worked as an internal filing tool that broke large blocks of numbers into smaller batches.
  • The last four digits are the serial number. Within each group they ran from 0001 to 9999, giving each person a unique identifier.

All nine digits together form the complete number the government uses to match your earnings record to your identity.1Social Security Administration. Social Security History – The SSN Numbering Scheme

Nine-Digit Patterns That Are Never Valid

Not every nine-digit combination is a real Social Security number. The SSA has always excluded certain patterns, and knowing them helps you spot a typo, a fabricated number, or an ITIN masquerading as an SSN.2Social Security Administration. The Story of the Social Security Number

  • No SSN starts with area number 000.
  • No SSN uses area number 666.
  • Area numbers 900 through 999 are reserved for IRS-issued Individual Taxpayer Identification Numbers, not for SSNs.
  • The middle two digits are never 00.
  • The last four digits are never 0000.

If a number you’re looking at contains any of these patterns, it isn’t a legitimate SSN.

Do the Digits Still Reveal Where the Number Was Issued

They used to. Before June 25, 2011, the area number corresponded to a specific state, and group numbers were issued in a predictable sequence within each area. Someone who knew where and roughly when you were born could make educated guesses about parts of your SSN. That predictability was useful for the SSA’s internal filing but valuable to identity thieves.

On that date, the SSA switched to a system called SSN Randomization. Area numbers no longer correspond to any state, and group numbers are no longer issued in a predictable order.3Social Security Administration. Social Security Number Randomization The change also opened previously unused area-number blocks, such as those in the 800s, extending the supply of available combinations. The total digit count stayed at nine, so nothing about the format changed for employers, banks, or the software systems that store SSNs.

Numbers assigned before the 2011 cutoff still carry their original geographic meaning and remain fully valid. If your card was issued in 1995, your area number still reflects where you applied. Randomization applies only to numbers issued after that date.4Social Security Administration. Social Security Number Randomization Frequently Asked Questions

Another Nine-Digit Number That Isn’t an SSN

The IRS issues a separate nine-digit number, the Individual Taxpayer Identification Number, to people who need to file a federal tax return but aren’t eligible for a Social Security number. An ITIN follows the same XXX-XX-XXXX format, which is why it’s easy to confuse the two at a glance. Two things distinguish it: an ITIN always begins with the digit 9, and its fourth and fifth digits fall within specific reserved ranges.5Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)

An ITIN is for federal tax purposes only. It doesn’t authorize employment, doesn’t establish eligibility for Social Security benefits, and can’t stand in for an SSN on a work-verification form. If the holder later becomes eligible for an SSN, the ITIN is deactivated; nobody holds both at the same time.5Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)

A Quick Way to Sanity-Check a Number

If you need to confirm that a nine-digit number in front of you could be a valid SSN, run through a short mental checklist. Count nine digits. Confirm the area number isn’t 000, 666, or in the 900s. Confirm the middle two digits aren’t 00 and the last four aren’t 0000. That won’t tell you whether the number actually belongs to a particular person, but it will catch most obvious errors and any number that was never a legitimate SSN to begin with.