Problem #

Your customer sees the following error while attempting to check out:

Invalid VAT number format for Germany.

Cause #

This error indicates that the VAT number that the customer entered is not a valid VAT number for their selected country.

If you selected Validate Format During Checkout or Validate at Checkout and with Relevant Authority for VAT Number Validation at Configuration () > System Settings > Tax Configuration, WHMCS will check whether VAT numbers use a valid format for selected countries during checkout.

It performs this check whenever a customer selects one of the following countries: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Northern Ireland, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, or the United Kingdom.

Solution #

Ensure that the customer’s entered VAT number and selected country are both correct.

Last modified: 2025 December 16