Legal Entity Identifier (LEI) Regex for PHP

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching legal entity identifier (lei), 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
// Legal Entity Identifier (LEI)
// ReDoS-safe | RegexVault — Finance > Tax & Registration

define('LEGAL_ENTITY_IDENTIFIER_LEI_PATTERN', '/^[A-Z0-9]{18}[0-9]{2}$/');

function validate_legal_entity_identifier_lei(string $input): bool {
    return (bool) preg_match(LEGAL_ENTITY_IDENTIFIER_LEI_PATTERN, $input);
}

// Example
var_dump(validate_legal_entity_identifier_lei("7H6GLXDRUGQFU57RNE97")); // 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

The first 4 characters identify the LOU (Local Operating Unit). Characters 5-18 are the entity-specific portion. The last 2 digits are check digits per ISO 17442 (MOD-97-10). Required by MiFID II and other regulations for financial reporting.