How is an SSN structured?

A US SSN is 9 digits in the form AAA-GG-SSSS: a 3-digit area number, a 2-digit group number, and a 4-digit serial number. None of these three parts may be all zeros.

Which SSN patterns are always invalid?

The area number cannot be 000, 666, or in the 900–999 range. The group number cannot be 00, and the serial number cannot be 0000. Numbers breaking any of these are never issued.

Does a valid format mean the SSN is real?

No. Structural validity only confirms the number could have been issued. It does not confirm the SSN belongs to a real, living person — that requires SSA verification (for example the SSNVS or eCBSV services).

Can this tool verify the holder's identity?

No. This is a format and known-invalid-pattern checker for pre-screening. Identity verification must go through the Social Security Administration's authorized services.

Is my SSN sent anywhere?

No. All checks run locally in your browser. The SSN never leaves your device, which matters for sensitive PII like this.

US Social Security Number Validator

A US Social Security Number (SSN) is the 9-digit identifier issued by the Social Security Administration, written as AAA-GG-SSSS. While the SSA stopped using geographic assignment in 2011 (randomization), a fixed set of structural rules still makes certain numbers permanently invalid. This free validator applies those rules to pre-screen SSNs during HR onboarding or KYC — without sending the sensitive number anywhere.

How it works

The SSN is split into three parts and each is checked against the SSA’s published exclusion rules:

Area number (first 3 digits) — must not be 000, 666, or in the range 900–999. The 900–999 block is reserved for ITINs, and 000/666 were never issued.
Group number (middle 2 digits) — must not be 00.
Serial number (last 4 digits) — must not be 0000.

If all three parts pass, the number is structurally valid (it could have been issued). If any part fails, the tool reports which specific rule was violated.

Example

Validate 123-45-6789 → area 123 (valid: not 000/666/900+), group 45 (valid: not 00), serial 6789 (valid: not 0000). The structure passes, so the SSN is format-valid.

Validate 666-12-3456 → area is 666, which is on the never-issued list, so it is rejected with a clear reason.

Tips and notes

A structurally valid SSN is not a guarantee the number was actually assigned to a real person. For authoritative verification, employers use the SSA’s Social Security Number Verification Service (SSNVS) or eCBSV. Because an SSN is highly sensitive PII, this tool never transmits it — all checks run entirely in your browser.