Invoices (asking for payment) are approved based on a "three-way match" of the purchase order/contract, the receiving document and the invoice. The purchase document and the receiving document confirm that the company got what was ordered and confirm the quantity accepted. The invoice indicates what the supplier expects to receive in compensation.

Before payment is issued any discrepancies must be identified and resolved. The form of payment is agreed upon during source determination and the preparation of the purchase order or contract. Usual forms of payment are cash, cheque, bank transfer, electronic transfer or letter of credit (LOC).