ERP
Three-way matching: how small businesses stop paying invoices they don't owe
Three-way matching snapshot
- In one line: three-way matching checks three documents before you pay a supplier — the purchase order, the goods received note, and the supplier's invoice — and only approves payment when they agree.
- Why it works: each document comes from a different person — a buyer, a receiver, and the supplier — so no one person can order, confirm receipt of, and approve payment for something that never existed.
Three-way matching is one of the simplest controls in accounting. Before paying any supplier bill, ask: did we order this, did it arrive, and is the price what we agreed? If any answer is no, hold the invoice and find out why.
Three-way matching: the three documents
The purchase order (PO) is raised by your business before the purchase. It proves the spend was authorised and fixes the agreed items, quantities, unit prices, and terms. A PO created after the invoice arrives proves nothing, so treat after-the-fact POs as exceptions.
The goods received note (GRN) is created by whoever receives the delivery. It proves what physically arrived, in what quantity and condition. It is your own record, not the supplier's packing slip, and it should be recorded by the person who received the goods, not the person who pays the invoices. If one person records receipts and approves payments, the separation the control depends on is gone.
The supplier invoice is the claim for payment. On its own it proves nothing except that the supplier wants to be paid.
Three-way matching: what gets compared
When an invoice arrives, compare it against the other two documents, line by line: the supplier, the items, the quantity (invoiced quantity must not exceed the quantity received on the GRN), the unit price (invoiced price must agree with the PO price), the line and total amounts, and tax and extra charges.
That split is why three documents are needed. Quantity is checked against the GRN — you pay for what arrived, not what you ordered. Price is checked against the PO.
Three-way matching: a worked example
A small bakery orders flour from its regular supplier. Its policy: a unit price variance up to 2% passes automatically, the invoiced quantity must not exceed the quantity received, and any charge not on the PO goes to the buyer.
The purchase order: 100 sacks at $12.00 each, $1,200.00 total. The goods received note: the delivery arrives and the baker counts 96 sacks; four are short and will follow later. The invoice: 100 sacks at $12.50 each, $1,250.00 total.
Matching line by line: quantity fails — invoiced 100, received 96, so only 96 sacks can be approved now. Price fails too — $12.50 against the agreed $12.00 is about 4.2% above the PO price, outside the bakery's 2% tolerance, so it goes to the buyer for a price check. Only 96 sacks at the agreed $12.00 — $1,152.00 — can be approved. The remaining $98.00 stays on hold: $48.00 for flour that had not arrived, and $48.00 of unagreed price increase. Across dozens of invoices, those small leaks add up to real money.
Three-way matching: tolerances and exceptions
Requiring exact matches on every line creates a queue of trivial exceptions — a few cents of rounding, a small price change the buyer already agreed. Tolerances let small differences pass automatically and send larger ones for review: a unit price tolerance (a percentage, such as 2%, above the PO price), a line or total amount tolerance (a percentage, a fixed amount, or both), and a quantity tolerance (often zero for over-invoicing — you should never pay for more than you received). Set tolerances by category: 2% is reasonable for flour, but may be too loose for high-value equipment.
An exception is a question, not a verdict. Most have one of a handful of answers, each with a clear owner: goods arrived but no GRN — the receiver records the receipt and the invoice re-matches; short delivery — pay for what was received and hold the rest, or ask for a credit note; price higher than the PO — the buyer confirms whether a new price was agreed, and if so amends the PO, or if not requests a corrected invoice; charges not on the PO — the buyer approves or disputes them against the supplier's terms.
Three-way matching: the fraud protection
It also protects against invoices that should never be paid at all. In May 2026, the US Federal Trade Commission warned that scammers send unsolicited invoices for products and services businesses never ordered, hoping someone in a busy back office pays without checking. A three-way match stops those cold: a fake invoice has no purchase order and no goods received note behind it, so it fails the match and lands in the exception queue instead of the payment run. The same check catches honest mistakes — duplicate invoices entered twice, a supplier billing for a delivery that went to another customer, a price typed wrong.
Three-way matching: when to use it, and when not to
Three-way matching is the standard for physical goods. Two-way matching — PO against invoice — suits services and low-risk items where there is no physical receipt, usually with a manager confirming the service was delivered. Four-way matching adds an inspection or quality check, and is used where goods must pass testing before acceptance. Many businesses use more than one: three-way for stock and equipment, two-way for subscriptions and professional services.
You do not need expensive software to start. A purchase order, a receipt note, and a habit of comparing the three before every payment run will catch most of the money leaking out of a small business.
If you want that habit built into your accounting, Point is the affordable accounting software we are building at Tetra M Labs — $9.99 a month for up to 5 users, with a 14-day free trial and no credit card required. Join the waitlist at tetramlabs.com.