IBAN-Formatted Account Display Regex for PHP

What this pattern does

This page provides a well-structured, multi-part regular expression for matching iban-formatted account display, 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
// IBAN-Formatted Account Display
// ReDoS-safe | RegexVault — Finance > Financial Formats

define('IBANFORMATTED_ACCOUNT_DISPLAY_PATTERN', '/^[A-Z]{2}[0-9]{2}(?:\s[A-Z0-9]{4})+(?:\s[A-Z0-9]{1,4})?$/');

function validate_ibanformatted_account_display(string $input): bool {
    return (bool) preg_match(IBANFORMATTED_ACCOUNT_DISPLAY_PATTERN, $input);
}

// Example
var_dump(validate_ibanformatted_account_display("GB29 NWBK 6016 1331 9268 19")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Financial Formats 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

Display-formatted IBANs use spaces every 4 characters (with the final group being 1-4 chars). Strip all spaces before any processing, lookup, or comparison. Store IBANs without spaces.