Adding a VAT number in Sage is fine and some check is done against the format of that number, but that does not mean that it is a valid VAT number. It would great if the VAT field was connected to the VIES website so that it could check to see if the number was valid or not. It would also be great for this to let the user know if and when that VAT number becomes invalid. Otherwise every VAT number in Sage needs to be checked monthly at the very least