Regex to Match Social Security Numbers

This regex validates US Social Security Numbers (SSN) in the standard XXX-XX-XXXX format with exclusions for known invalid ranges. Here is the token-by-token breakdown:

^ — Anchors the match at the start of the string.

(?!000|666|9\d{2}) — A negative lookahead that rejects invalid area numbers. The SSA has never issued SSNs starting with 000 or 666, and numbers starting with 9XX were reserved for the Individual Taxpayer Identification Number (ITIN) program. This lookahead checks ahead without consuming characters.

\d{3} — Matches exactly three digits for the area number (first three digits).

• — Matches a literal hyphen separator.

(?!00) — A negative lookahead rejecting group numbers of 00, which are not valid in real SSNs.

\d{2} — Matches exactly two digits for the group number (middle two digits).

• — Matches a literal hyphen separator.

(?!0000) — A negative lookahead rejecting serial numbers of 0000, which are not valid.

\d{4} — Matches exactly four digits for the serial number (last four digits).

$ — Anchors the match at the end of the string.

This pattern enforces the correct format and excludes ranges that the Social Security Administration has declared invalid. Note that this is a format validation only; it does not verify that the SSN has actually been issued. Handle SSN data with appropriate security measures, as it is sensitive personally identifiable information.