LEI Validator (Legal Entity Identifier)

LEI: the 20-character global Legal Entity Identifier (ISO 17442)

The LEI (Legal Entity Identifier) is a 20-character alphanumeric code that uniquely identifies a legal entity participating in financial transactions anywhere in the world. Created after the 2008 financial crisis and standardised as ISO 17442, it is governed by GLEIF and issued by accredited LOUs (Local Operating Units). This tool validates the structure and the two check digits.

The last two characters are an ISO 7064 mod-97-10 checksum over the first 18, so a mistyped LEI is caught arithmetically — the same checksum family used by IBAN. The example 529900T8BM49AURSDO55 validates against that scheme.

Structure of a LEI

• Characters 1–4: the LOU prefix — which issuing organisation assigned the LEI.
• Characters 5–6: reserved, always 00.
• Characters 7–18: the entity-specific part (alphanumeric, uppercase).
• Characters 19–20: the mod-97 check digits.

Where it matters

• Regulatory reporting: MiFID II, EMIR and Dodd-Frank require an LEI for trade reporting.
• Counterparty identity: it answers "who is the legal entity?" across borders and registries.
• Open data: the GLEIF database maps each LEI to the entity's legal name, address and ownership.
• Mock data / testing: validating the ISO 17442 structure and checksum before a GLEIF lookup.

Common pitfalls

• Checksum ≠ registered: a valid mod-97 doesn't mean GLEIF has an active record — and LEIs must be renewed annually.
• Uppercase only: normalise to uppercase; lowercase input is not canonical.
• Lapsed LEIs: an entity's LEI can be "lapsed" if not renewed — structurally valid but not current.
• LEI ≠ national company number: it sits above local registries (CNPJ, Companies House), not instead of them.

FAQ

How is the LEI checksum computed? ISO 7064 mod-97-10 over the first 18 characters (letters expanded to numbers), exactly like IBAN's check.

Does an LEI expire? The number doesn't change, but registration must be renewed yearly or it lapses.

Who needs an LEI? Any legal entity trading regulated financial instruments — companies, funds, trusts — not individuals.