VIES: why it pays to validate every EU VAT number before you invoice

If you sell B2B across the EU, you've probably typed a customer's VAT number into VIES at least once. What most people miss is that VIES is not a formatting check — it's the European Commission asking the member state's tax authority, in real time, whether that number is registered and active. That distinction matters when the tax office later disagrees with how you treated a sale.

The 60-second background

VIES (VAT Information Exchange System) is the EC service that lets you verify a counterparty's VAT id is valid for intra-EU transactions. It says whether the number exists in that country's register and (depending on the country) whether the business's name and address match.

What it doesn't do:

• Tell you whether the business is solvent.
• Tell you whether the registration is the right one for the kind of

supply you're making.

• Guarantee that the number will still be valid tomorrow.

That last point is why a validation should happen at the moment of invoicing, not once a year.

Why this is high-stakes

When you invoice an EU B2B customer outside your country, you usually apply reverse charge: you don't charge VAT, your customer accounts for it. But reverse charge is only available if you have a valid, intra-EU VAT id for the buyer at the time of the supply.

If the number turns out to be wrong, formerly valid, or non-existent, the tax office can re-characterise the sale as a domestic one — which means VAT becomes due, and at your own country's rate, on top of the amount you already invoiced. That's almost always a worse outcome than catching the bad number on send.

In Belgium specifically, the VAT administration expects you to be able to show proof of the VIES check at the time you treated the supply as exempt. A printout, a stored confirmation, or a journal entry are all fine — what's not fine is "I assumed it was valid."

What "valid for intra-EU" really means

A VAT registration can exist and not be valid for intra-EU supplies. Some countries (Spain, Italy, others) require an explicit opt-in to the "intra-community operators" register — VIES will say "invalid" for an otherwise live VAT number that hasn't been added to that register.

So when VIES says invalid, don't assume your customer is wrong about their own number. Ask them to confirm they're registered for intra-EU operations in their country. Often the fix is a five-minute filing on their side.

How to make this automatic

Manual checks before every invoice are the kind of compliance step people skip on their busiest day. Two settings that make it cheap:

1. Validate clients on creation. Eurobillr runs VIES when you add a

client with an EU VAT number — bad numbers get flagged immediately, not at year-end.

1. Re-check on flagged supplies. Before applying reverse charge on a

new invoice, Eurobillr can re-validate the number; if it's gone invalid since you added the client, you'll know before the document is issued.

The recapitulative listing (the intra-community sales statement) is the other backstop. Eurobillr generates it from the same data, so a mismatch between what you reported and what your customer's tax office saw is far less likely.

What to do today

• Add the VIES check to your "new client" routine, even if you're

pretty sure the number's good.

• Store the confirmation. Eurobillr keeps a timestamped record per

client, which is what you'd want if the question ever came up.

• Set a reminder to re-validate active EU customers annually. Numbers

do get cancelled.

Background reading: the VIES glossary entry, reverse charge, and the intra-community supply term.