A three-way match is a process of verifying that a purchase order, a goods receipt and an invoice are consistent before making a payment1. A three-way match ensures that the organization only pays for the goods or services that it ordered and received, and that the prices and quantities are accurate. A three-way match can prevent errors, fraud and overpayments in the accounts payable process.

An IS auditor should use a purchase order when verifying a three-way match has occurred in an enterprise resource planning (ERP) system. A purchase order is a document that authorizes a purchase transaction and specifies the items, quantities, prices and terms of the order2. A purchase order is the first document in the three-way match process, and it serves as the basis for comparing the goods receipt and the invoice. An IS auditor can use a purchase order to check if the ERP system has correctly recorded, matched and approved the three documents before making a payment.

The other options are not as useful for verifying a three-way match. A bank confirmation is a document that verifies the balance and activity of a bank account3. A bank confirmation can be used to confirm that a payment has been made or received, but it does not provide information about the details of the purchase transaction or the three-way match process. A goods delivery notification is a document that informs the buyer that the goods have been shipped or delivered by the seller4. A goods delivery notification can be used to track the status of the delivery, but it does not provide information about the quantity or quality of the goods or the invoice amount. A purchase requisition is a document that requests authorization to purchase goods or services from a specific supplier2. A purchase requisition can be used to initiate the purchasing process, but it does not provide information about the actual purchase order, goods receipt or invoice.