I guess this thread is not realy needed anymore.
Open vatnumbervalidation.php in the current download WHMCS and follow instructions to nicely include/exclude VAT for the european countries.
I have to implement a different method for applying VAT for EU citizents.
I have a custom field "check-box" to allow the customer to choose if he wants to receive invoice (for companies) or receipt (for individuals). ...Yes we have 2 different types in Greece...
So, I have implemented a VAT type for EU citizens but it just not apply any VAT if the selected country is in EU.
The problem is that it must charge VAT if the customer is in EU and he has not the check-box selected.
The custom filed has the ID "customfield10" and the name "customfield"
Any idea how to implement this?