What information does a proforma invoice require?
Just send a normal invoice with the payment due on presentation as the payment terms. You don’t need to use wording like “proforma” on it, a standard invoice will do as it is in fact a standard commercial invoice you need to send out as you expect to be paid before the goods are dispatched. “Proforma” invoices are like quotes, almost identical to commercial invoices except they are not for payment – most commonly used to accompany shipping documents to prove the value of shipments for example.