Three-Way Match: How It Works and When It's Worth Doing

The process has four steps, and each one depends on the last:

1. Issue a purchase order (PO) before the purchase. It lists the vendor, items, quantities, agreed unit prices and payment terms.
2. Record receipt. When goods arrive, the receiving team logs what was actually delivered against the PO number.
3. Match the invoice. AP compares the invoice to the PO and the receiving record on quantity, unit price, extended amount and terms.
4. Approve or hold. A clean match goes to payment. A mismatch goes to an exception queue with a reason code.

The value comes from the separation. The person who orders, the person who receives and the person who pays are different, so one person can't create a purchase, confirm it and pay for it alone.

For example, say you order 100 units at $12 each on a PO. The warehouse receives 90 units and logs them. Say the vendor invoices you for all 100 units, a total of $1,200. A two-way match of PO and invoice would pass this, because the invoice agrees with the order. The three-way match catches it. Say you received 90 units: you owe $1,080 and the invoice is short-shipped by 10 units.

Your options in that case are to pay for what you received and ask for a credit note, to hold the invoice until the remaining units arrive or to pay in full and record a claim against the vendor. The first two keep your bargaining position. The third gives it away.

Other common mismatches: a unit price that changed since the PO, freight or tax added without agreement, an invoice that arrives before the goods and a second invoice for the same order. Give each one a reason code so you can see over time which vendors cause the most exceptions.

Exact matches on every invoice will drown you in exceptions, so set tolerances. A common approach is to allow small price or quantity differences, either as a percentage or a dollar amount, and require review above that. For example, you might auto-approve a price variance up to two percent or five dollars, whichever is lower, and route anything bigger to the buyer.

Tolerances work best when they reflect the goods. Bulk commodities that vary in weight need looser quantity tolerances than serialized equipment. High-value items should have tighter limits, even zero. Write the tolerances into your AP procedure, and review them after a quarter of data to see which exceptions were worth catching.

Also decide who resolves each type of mismatch. Price problems belong to the buyer who negotiated. Quantity problems belong to whoever receives goods. Coding and tax problems belong to AP.

Match the control to the risk:

• Two-way (PO and invoice): suitable for services and subscriptions where there's nothing to receive, once the PO or contract terms are set.
• Three-way (PO, receipt and invoice): suitable for inventory, equipment and supplies, and for any purchase where delivery can be short, late or wrong.
• Four-way (adds inspection or acceptance): suitable where quality matters, such as manufacturing components or construction milestones.
• No match, approval only: small recurring bills such as utilities, where the cost of matching exceeds the risk.

For a small business, a sensible rule is to require a PO and three-way match above a dollar threshold on physical goods, and a manager's approval for everything else. The threshold belongs in your spend policy so people know when to create a PO first.

Three-way matching fails when the pieces aren't reliable. Before you switch it on, check that:

• POs are created before purchase, not after the invoice arrives.
• Someone logs receipts promptly, ideally the same day, with the PO number.
• Vendors put the PO number on their invoices, and you tell them that invoices without one will be delayed.
• Your AP tool or spreadsheet can show all three records side by side.

Purchasing platforms such as Procurify can issue POs and track receipts, and spend platforms like Ramp can connect purchases to approvals. Compare card and spend options in Brex vs Ramp vs Navan. Ask in a demo how matching tolerances and exceptions are handled, and how it connects to your accounting system. The wider process is in the accounts payable process guide.