EU VAT Number Check

A VAT identification number (VATIN) is a unique identifier assigned to businesses registered for Value Added Tax in European Union member states. Each number starts with a two-letter country code followed by a sequence of digits (and in some countries, letters) specific to that country's format.

Why validate VAT numbers?

When selling goods or services to a business in another EU country, you need to verify their VAT number to apply the reverse charge mechanism. This allows you to zero-rate VAT on the invoice — but only if the buyer's VAT number is valid and registered in VIES. Failing to verify can leave you liable for the VAT.

Cross-border B2B transactions

Under EU VAT rules, intra-community supplies of goods and services between VAT-registered businesses can be exempt from VAT in the seller's country. The buyer accounts for VAT in their own country instead (reverse charge). This system relies on both parties having valid, verifiable VAT numbers.

Format validation vs. VIES check

There are two levels of VAT number validation. Format validation checks whether the number matches the expected pattern for its country — correct length, correct character types. A VIES check goes further: it queries the EU's central database to confirm the number is actually registered and active with the national tax authority.

What "valid" really means

A valid result from VIES means the number is currently registered in the national VAT database of the relevant member state. It does not guarantee the business is actively trading or that it is authorized for specific types of transactions. For due diligence, combine VAT validation with other checks when dealing with new trading partners.

Common validation patterns

Most EU countries use check digits — mathematical formulas applied to the number that help catch typos and data entry errors. For example, Germany uses the ISO 7064 MOD 11,10 algorithm. These checks happen before the number is even sent to VIES, saving time on obviously incorrect numbers.