Legal Entity Identifier (LEI) Regex for Go

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching legal entity identifier (lei), 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

// Legal Entity Identifier (LEI)
// ReDoS-safe | RegexVault — Finance > Tax & Registration

package validation

import "regexp"

var legalEntityIdentifierLeiRe = regexp.MustCompile(`^[A-Z0-9]{18}[0-9]{2}$`)

func ValidateLegalEntityIdentifierLei(s string) bool {
    return legalEntityIdentifierLeiRe.MatchString(s)
}

// Example
// fmt.Println(ValidateLegalEntityIdentifierLei("7H6GLXDRUGQFU57RNE97")) // 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 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

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.