Singapore UEN (Unique Entity Number) Regex for PHP

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching singapore uen (unique entity number), ported and verified for PHP. 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 PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

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

define('SINGAPORE_UEN_UNIQUE_ENTITY_NUMBER_PATTERN', '/^(?:[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 validate_singapore_uen_unique_entity_number(string $input): bool {
    return (bool) preg_match(SINGAPORE_UEN_UNIQUE_ENTITY_NUMBER_PATTERN, $input);
}

// Example
var_dump(validate_singapore_uen_unique_entity_number("200312345A")); // bool(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 PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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).