VAT Number Validator

How it is calculated

Spaces, hyphens and dots are removed and letters are made uppercase. The first two characters are read as the country prefix and the rest as the body, which is then tested against a fixed pattern. Only five countries are known: DE (9 digits), FR (2 letters or digits + 9 digits), IT (11 digits), ES (any 9 letters or digits) and NL (9 digits + B + 2 digits). A number from any other country, even a real EU one such as BE or PL, is reported as invalid with an unrecognized prefix.

For Germany the tool also runs the ISO 7064 MOD 11,10 check on the first eight digits: p = 10; for each digit: m = (digit + p) mod 10, with 0 taken as 10; p = 2m mod 11, and the check digit is (11 − p) mod 10. A German number whose last digit does not match is still marked as valid format, with a note that the check digit does not match. Nothing is looked up in VIES or any tax register.

Common mistakes

• Treating “Valid format” as proof that the company is registered. The tool never contacts a registry, so a correctly shaped number can still be unassigned, cancelled or belong to someone else.
• Entering a VAT number from a country outside DE, FR, IT, ES and NL. It is shown as invalid with an unrecognized prefix even though the number may be perfectly good, so use the official EU VIES service for those.
• Omitting the country prefix, as in 136695976 alone. The first two characters must be the prefix, so the tool reports an unrecognized prefix and cannot work out the country.
• Ignoring the checksum note on a German number. DE136695977, for example, passes as a format but reports that the check digit does not match, which is a typical typing or transcription error.
• Expecting stricter Spanish or French rules. The tool only checks length and allowed characters there, so a random 9-character string after ES still passes.