VAT number must be in the Adress fields in the Costumer Information in the Store Administration-Configuration-Checkout settings. This way, we can append the title (VAT in EU, CIF for Spain only, NIF, etc., the store can select the name prefered). User from others conuntries that don´t use VAT could use this field to store the customer code that prefer (the countable code for example) or leaving blank. Also a verification square with the posibilities to make the field visible or not visible in the invoices. No ecommerce systems that I know considers that VAT in EU is so important or more that the customer name or hs adress. And this is the big error. Please you must think about this as if you were the one EU store owner. Thanks.