A lot of our purchases are made from US suppliers, but when you input supplier details the default is a UK supplier, with an option to say that they are from elsewhere in the EC. This means that 20% VAT is always added automatically when inputting the purchase. However, when adding a new customer, there is a box to tick to indicate that they are from out of the EU - there needs to be one for new suppliers, too.
I may be wrong as I fairly new to kashflow - but I just tested this and if you don't put a VAT number against the supplier, the VAT rate on any item you add to a purchase is defaulted to 0% - isn't this the same thing as no VAT is being calculated?