When you receive an invoice from a European supplier or onboard a new B2B customer in the EU, verifying their VAT number is an important compliance step. An invalid or fraudulent VAT number can mean you cannot apply the reverse charge mechanism correctly — leaving you exposed to unexpected VAT liabilities.

Two Levels of VAT Number Validation

There are two ways to validate an EU VAT number, and you should understand the difference:

1. Format Validation

Each EU member state has a specific format for VAT numbers — a country prefix followed by a set number of digits and/or letters. Format validation checks whether the number matches the correct pattern for that country. This is what our free VAT Number Validator does — instantly, in your browser, with no data sent anywhere.

2. VIES Registration Check

The EU's VIES system (VAT Information Exchange System) allows you to check whether a VAT number is actually registered and active in the EU database. This is a live check against the national tax authority databases of all member states. You can access VIES at ec.europa.eu/taxation_customs/vies/.

EU VAT Number Formats by Country

When Should You Validate a VAT Number?

• Before issuing a zero-rated B2B invoice — to justify applying the reverse charge
• When onboarding a new EU supplier or customer
• If a VAT number looks unusual — wrong length, wrong prefix, or unusual characters
• Before processing a large transaction

What if a VAT Number Fails Validation?

If a format check fails, ask the customer to double-check the number. If a VIES check fails but the format is correct, it may mean the business is not yet VAT-registered in the EU, is registered only domestically, or their record has not propagated to the VIES system (this can take a few days for new registrations). In case of doubt, request a copy of their VAT registration certificate before applying reverse charge.