Australian BSB (Bank-State-Branch) Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching australian bsb (bank-state-branch), 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 BSB (Bank-State-Branch)
// ReDoS-safe | RegexVault — Finance > Bank Identifiers

const australianBsbBankstatebranchRegex = /^[0-9]{3}-?[0-9]{3}$/;

function validateAustralianBsbBankstatebranch(input: string): boolean {
  return australianBsbBankstatebranchRegex.test(input);
}

// Example
console.log(validateAustralianBsbBankstatebranch("062-000")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Bank Identifiers 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

First digit identifies the financial institution (0=ANZ, 1=WBC/STV, 2=CBA, 3=NAB, 6=CUSCAL/regionals). Second digit is the state. Validate against APCA's BSB directory for active accounts.