Australian Business Number (ABN) Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching australian business number (abn), 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

// Australian Business Number (ABN)
// ReDoS-safe | RegexVault — Finance > Tax & Registration

const australianBusinessNumberAbnRegex = /^[0-9]{2}\s?[0-9]{3}\s?[0-9]{3}\s?[0-9]{3}$/;

function validateAustralianBusinessNumberAbn(input: string): boolean {
  return australianBusinessNumberAbnRegex.test(input);
}

// Example
console.log(validateAustralianBusinessNumberAbn("51824753556")); // 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

Format validation only. ABN checksum: subtract 1 from first digit, multiply each by weight (10,1,3,5,7,9,11,13,15,17,19), sum, divide by 89, remainder must be 0. Validate via ABR (Australian Business Register) for active status.