SSN format validator.

What this check means

An SSN is written AAA-GG-SSSS: a three-digit area number, a two-digit group number and a four-digit serial number. A pass here means the digits break none of the SSA's published rules. It does not mean the number was issued, and an SSN has no checksum, so no tool can verify one from the digits alone. Only the SSA can confirm a number, for example through its Social Security Number Verification Service for employers.

The rules this tool applies

• Area (first 3 digits): 000, 666 and 900-999 are never assigned.
• Group (middle 2 digits): ranges 01-99, so 00 is rejected.
• Serial (last 4 digits): runs 0001-9999, so 0000 is rejected.
• Known misused numbers: 078-05-1120 (printed in a 1938 wallet sample) and 219-09-9999 (shown in a 1940 SSA pamphlet) are flagged. Both fit the pattern, but the SSA documents them as specimen numbers that were widely misused.

Randomization since 2011

The SSA changed how SSNs are issued on June 25, 2011. Area numbers no longer map to a state, so the first three digits of a newer SSN say nothing about where its holder lived. Before 1972 the area reflected the office that took the application, and from 1972 the ZIP code on the application. Older numbers still carry that history, but it was never meant as usable geographic data.

Sources

Rules checked 2026-09-30 against the SSA pages Social Security Number Randomization (June 25, 2011 change; areas 000, 666 and 900-999 excluded), The SSN Numbering Scheme (area, group and serial structure; serials 0001-9999; groups 01-99) and Misused Social Security Numbers (078-05-1120 and 219-09-9999). The SSA site can block automated requests, so these were read through an archived copy of each page.

Frequently asked questions

Is there a checksum for a Social Security number?

No. Unlike a Canadian SIN or a credit card, an SSN has no check digit, so a format check can only rule numbers out. It cannot confirm that a number was issued to anyone.

Which SSNs are impossible?

Per the SSA, area numbers 000, 666 and 900-999 are not assigned. Group 00 and serial 0000 are also not used.

Does the first three digits still show which state issued an SSN?

Not for numbers issued since June 25, 2011. SSA randomization ended the link between the area number and a state.

Is it safe to type an SSN here?

The check runs as JavaScript in your browser. Nothing is sent, stored or logged. Still, only enter a number you are entitled to use.