Three way matching in accounts payable is the practice of checking a supplier invoice against two other documents before it is paid: the purchase order that authorised the purchase, and the goods receipt that records what arrived. If all three agree on supplier, quantity and price, the invoice is paid. If they do not, it is an exception for a person to resolve. That is the whole idea, and it is worth stating plainly because the term arrives wrapped in software marketing that makes it sound like a product rather than a control. It is a control. It can be done on paper, in a spreadsheet, or automatically, and this page explains what it protects against and what it does not.
The three documents in order of when they exist
First the purchase order: somebody decided to buy something and had the authority to. Then the goods receipt: it arrived, and here is how much of it. Last the invoice: the supplier asks to be paid. Matching runs backwards through that history to confirm the claim is consistent with what happened.
What it protects against
Paying for goods that never arrived, paying twice for the same delivery, paying a price nobody agreed, and paying an invoice nobody ordered. Those are the four commonest ways money leaves a business incorrectly through payables, and the match addresses all four with one comparison.
What it does not do
It does not tell you the purchase was sensible, that the price was competitive, or that the service was any good. It confirms consistency between three records, which is a narrower and more useful claim than the word verification usually implies.
Questions people ask about what is three way matching in accounts payable
Is two way matching not enough?
It depends what you buy. Two way matching, invoice against order, confirms the price was agreed but not that anything arrived. For physical goods that gap matters; for a fixed-fee service with no delivery record it may be the most that is available.
Do small businesses need it?
Where purchase orders are used, yes, and the effort is small. Where they are not, introducing purchase orders is the bigger change and the one worth deciding on its own merits.
Where does the match happen?
Wherever the three records meet. In a small team that is often a person with three tabs open, which works and does not scale. The point of software here is consistency, not novelty.