Singapore UEN (Unique Entity Number) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching singapore uen (unique entity number), 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

// Singapore UEN (Unique Entity Number)
// ReDoS-safe | RegexVault — Finance > Tax & Registration

const singaporeUenUniqueEntityNumberRegex = /^(?:[0-9]{8}[A-Z]|[0-9]{9}[A-Z]|[RT][0-9]{2}[A-Z]{2}[0-9]{4}[A-Z]|S[0-9]{2}[A-Z]{2}[0-9]{4}[A-Z])$/;

function validateSingaporeUenUniqueEntityNumber(input: string): boolean {
  return singaporeUenUniqueEntityNumberRegex.test(input);
}

// Example
console.log(validateSingaporeUenUniqueEntityNumber("200312345A")); // 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

Business types: 9-char (8 digits + check letter) for older entities, 10-char for newer. T/R/S prefixes indicate specific registration types (GST, foreign entity, societies).