US Social Security Number (SSN) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching us social security number (ssn), ported and verified for JavaScript. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

// US Social Security Number (SSN)
// ReDoS-safe | RegexVault — Finance > Tax & Registration

const usSocialSecurityNumberSsnRegex = /^(?!(?:000|666|9[0-9]{2})-)[0-9]{3}-(?!00-)[0-9]{2}-(?!0{4})[0-9]{4}$/;

function validateUsSocialSecurityNumberSsn(input: string): boolean {
  return usSocialSecurityNumberSsnRegex.test(input);
}

// Example
console.log(validateUsSocialSecurityNumberSsn("123-45-6789")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Tax & Registration category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Invalid SSN ranges: 000-XX-XXXX (area 000), 666-XX-XXXX, 900-999-XX-XXXX. Group 00 and serial 0000 are also invalid. The pre-2011 geographic assignment pattern is no longer used.