Why identifier formats matter
Every European business identifier follows a published format specification. The format defines the exact length, character types, and structure that a number must have to be structurally valid. A number that fails the format check will be rejected by official verification systems — VIES, the EORI checker, GLEIF, or HMRC — before any registration lookup is even attempted.
Format errors are the most common reason an identifier check fails at the first step. Transposed digits, a missing country prefix, spaces copied from a PDF, or a wrong prefix for a country (the most notable example being Greece, which uses EL rather than GR in VIES) all produce structural failures that could have been caught before reaching the official service.
This guide lists the official format patterns for all four identifier types covered by EU Verifier. The patterns are based on the specifications published by the European Commission (for EU VAT and EORI), ISO 17442 (for LEI), and HMRC (for UK VAT). Where national variations exist — such as Ireland's multiple VAT number patterns or the Netherlands' suffix requirement — those are noted.
Quick reference: identifier types at a glance
| Identifier | Prefix | Total length | Verified via | Purpose |
|---|---|---|---|---|
| EU VAT | 2-letter country code | 8–14 chars total | VIES (European Commission) | VAT registration for EU cross-border trade |
| EORI | 2-letter country code | Up to 17 chars total | EC customs portal | Customs identification for import/export |
| LEI | 4-char LOU prefix | Always 20 chars | GLEIF Global LEI Index | Legal entity ID for financial transactions |
| UK VAT | GB or XI | 9–12 chars | HMRC | UK VAT registration (post-Brexit) |
EU VAT Number Formats
All 27 EU member states. The VIES prefix shown is the prefix used in the VIES system — note Greece uses EL not GR.
EORI Number Format
EORI numbers share a common structure across all EU member states.
| Element | Description | Example |
|---|---|---|
| Country prefix | ISO 2-letter country code of issuing customs authority | DE, FR, NL |
| Identifier body | Up to 15 alphanumeric characters, defined by national customs authority | 1234567890 |
| Full EORI | Prefix + body, total max 17 characters | DE1234567890 |
LEI Code Format
Legal Entity Identifiers are standardised by ISO 17442 and always 20 characters.
| Characters | Meaning | Example |
|---|---|---|
| 1–4 | LOU prefix — identifies the issuing Local Operating Unit | 5493 |
| 5–18 | Entity-specific alphanumeric characters assigned by the LOU | 00KJTIIGC8Y1R1 |
| 19–20 | Two check digits calculated using ISO 17442 modulo 97 algorithm | 12 |
| Full LEI | Always exactly 20 uppercase alphanumeric characters | 5493001KJTIIGC8Y1R12 |
UK VAT Number Formats
Post-Brexit UK VAT numbers are not part of the VIES system and must be verified via HMRC.
How to read the format patterns
The format patterns in this guide use a plain-English notation rather than raw regular expressions. Here is how to interpret them:
- "digits" means numeric characters 0–9 only. Letters and special characters are not valid in a digits-only field.
- "alphanumeric" means letters A–Z (uppercase) and digits 0–9. Lowercase letters, spaces, and special characters are not valid.
- A fixed character (such as the "U" in Austria's ATU format, or the "0" required in Belgium's format) must appear exactly as shown — it is not a wildcard.
- Length refers to the number of characters after the country prefix, unless "total length" is specified. For tool input purposes, always enter the number body without the prefix, unless the tool instructions specify otherwise.
- Alternative patterns (such as Ireland's multiple VAT formats) mean the number is valid if it matches any one of the listed patterns.
Common format pitfalls by identifier type
| Identifier | Most common error | How to avoid it |
|---|---|---|
| EU VAT | Entering the country prefix in the number field when it's already selected separately | Enter only the number body (e.g. 123456789 not DE123456789) |
| EU VAT (Greece) | Using GR prefix instead of the correct VIES prefix EL | Greece always uses EL in VIES regardless of ISO country code |
| EORI | Omitting the country prefix entirely | EORI numbers always begin with the 2-letter ISO country code |
| LEI | Entering fewer than 20 characters, or inserting a space after character 4 | LEIs are exactly 20 contiguous alphanumeric characters, no separators |
| UK VAT | Searching a GB-prefix number on VIES instead of HMRC | GB numbers left VIES on 1 January 2021; use the HMRC checker for all GB-prefix numbers |
Format check vs. registration check
A format check and a registration check are two distinct steps. This guide (and the format tools on this site) covers the first step only: confirming the number's structure is plausible. A number can pass every format check and still be unregistered, deregistered, or assigned to a different entity. Only the official source — VIES, the EORI checker, GLEIF, or HMRC — can confirm current registration status. Always complete both steps for compliance-sensitive workflows.