IBAN (UK — GB) Regex for Go

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching iban (uk — gb), ported and verified for Go. 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 Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// IBAN (UK — GB)
// ReDoS-safe | RegexVault — Finance > Bank Identifiers

package validation

import "regexp"

var ibanUkGbRe = regexp.MustCompile(`^GB[0-9]{2}[A-Z]{4}[0-9]{14}$`)

func ValidateIbanUkGb(s string) bool {
    return ibanUkGbRe.MatchString(s)
}

// Example
// fmt.Println(ValidateIbanUkGb("GB29NWBK60161331926819")) // 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 Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. 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

UK IBANs are always 22 characters. The 4-char bank code is a subset of the BIC. UK personal accounts typically have 8-digit account numbers. Building society accounts may differ.