Guides · Updated 6 October 2026

How to check an EU VAT number before you invoice

Why checking a customer’s VAT number matters for zero-rating and the reverse charge, how to do it properly, and the mistakes that catch people out.

Why it matters

When you sell to a business in another EU country, you usually don't charge your own VAT: goods go out VAT-free as an intra-Community supply, and for most services the customer accounts for the VAT under the reverse charge. Both depend on the customer being a VAT-registered business, and their VAT number is how you show it.

If the number turns out to be invalid, the tax authority can treat the sale as made to a private person, and ask you for the VAT you didn't charge. Checking the number, and being able to show you did, is your protection.

How to check it properly

1. Get the full number, with its country prefix, e.g. DE123456789. The prefix tells VIES which country to ask. See what VAT numbers look like in each country.
2. Check it in VIES, the European Commission's VAT Information Exchange System, which asks the customer's national tax database in real time. A format that merely looks right isn't enough: the number must be active now.
3. Compare the name and address with the company you're dealing with, where the country returns them. A valid number belonging to a different company is a common fraud trick.
4. Keep a record: the number, the date and time, and the result. If you also give VIES your own VAT number, it returns a consultation number, an official reference that proves the check took place.
5. Check again regularly for repeat customers. Companies close and lose their registration; a number that was valid last year may not be today.

Mistakes that catch people out

• Greece uses EL, not GR, as its VAT prefix.
• Germany and Spain don't return the company name: VIES only confirms the number is valid, so the name check is up to you.
• A German Steuernummer isn't a VAT number. Only the USt-IdNr. (DE + 9 digits) works in VIES.
• UK (GB) numbers left VIES after Brexit; they're checked with HMRC. Northern Ireland businesses trading goods with the EU have an XI number, which VIES does check.
• "Service unavailable" isn't "invalid". When a country's database is down, VIES can't answer either way. See what to do when VIES is down.

Checking many numbers

For a whole customer or supplier list, upload a spreadsheet and download the results, or check numbers automatically at sign-up or checkout with the VAT validation API. Watched numbers can be re-checked daily, with an alert if one stops being valid.

This guide is general information, not tax or legal advice. Rules and their application differ by country and by transaction; check with an adviser for your situation.

More guides

• VIES is down: what it means and what to do
• The reverse charge explained: EU and UK B2B sales
• How often should you re-check a customer’s VAT number?
• What proof of a VAT number check should you keep?
• EORI numbers explained: EU, GB and XI
• Northern Ireland XI numbers: VAT and EORI
• Checking Swiss and Norwegian VAT numbers
• Sanctions screening for small businesses
• Fake invoices and changed bank details: how to spot supplier fraud
• Peppol e-invoicing: what it is and how to check a customer