---
title: How to Validate a VAT Number (VIES & Registers)
description: VIES confirms whether an EU VAT number is registered for cross-border trade. Here is how it differs from national registers and what each check returns.
canonical: https://stanzaapi.com/guides/how-to-validate-a-vat-number
---

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# How to Validate a VAT Number (VIES and National Registers)

VAT number validation is two different checks: VIES confirms an EU VAT number is registered for intra-EU trade, while a national register confirms a domestic registration.

Updated 2026-09-30 · 5 min read

## What a VAT number is

A VAT identification number is issued by a tax authority to a business that is registered for value added tax. In the EU it carries a two-letter country prefix followed by the national number, such as DE for Germany or EE for Estonia.

The prefix makes the number unambiguous across borders, but it does not tell you whether the number is active. The national authority holds that state.

## VIES versus national registers

VIES (VAT Information Exchange System) is the European Commission’s service that checks whether a number is registered for intra-EU trade. It is the correct check before applying the reverse-charge mechanism on a cross-border B2B invoice.

A national register, run by the country’s own tax authority, is the correct check for a domestic relationship. VIES may report a number as invalid even when the business is registered domestically, because VIES covers only intra-EU trade registrations.

## Formats differ by country

There is no single European VAT format. A validator must apply the national pattern after the country prefix.

| Country | Prefix | National pattern |
| --- | --- | --- |
| Germany | DE | 9 digits |
| Ireland | IE | 7 digits plus 1–2 letters |
| Estonia | EE | 9 digits |
| Hungary | HU | 8 digits |
| Bulgaria | BG | 9 or 10 digits |
| Romania | RO | 2 to 10 digits |
| Italy | IT | 11 digits |
| Malta | MT | 8 digits |

## What validation can and cannot tell you

A format check confirms the number is structurally possible for the country. A VIES or register lookup confirms the registration status at the moment of the query.

Neither confirms that the business is trustworthy, that the invoice is correct, or that the number will still be valid tomorrow. Registrations are created and cancelled continuously.

## Common mistakes

Most validation defects are simple and predictable.

- Leaving spaces, dots, or the country name in the number before checking.
- Treating a VIES failure as proof the business does not exist.
- Applying one country’s format to every number in a batch.
- Skipping VIES for cross-border B2B and losing the reverse-charge defensibility.

## Try it on real data

[EU & UK VAT Validator & Rate Engine API → — Deterministic offline checksum validator for EU-27 and UK VAT numbers with instant 2026 standard & reduced tax rate lookups — Open the tool](/tools/vat-validator/)

## Frequently Asked Questions

What is VIES?

VIES is the EU VAT Information Exchange System. It confirms whether a VAT number is registered for intra-EU trade so a business can justify the reverse-charge mechanism on a cross-border B2B invoice.

Does VIES cover every VAT number?

No. VIES covers VAT numbers registered for intra-EU trade. A number that is registered domestically but not for cross-border trade can return invalid in VIES while still being active nationally.

Do EU VAT numbers have a check digit?

Some national formats include a check digit and some do not. A validator should always apply the country-specific rule rather than assuming one algorithm across the EU.

## Primary sources

- [European Commission — VIES (VAT Information Exchange System)](https://ec.europa.eu/taxation_customs/vies/)
- [European Commission — VAT identification numbers](https://taxation-customs.ec.europa.eu/)