3 way matching in accounts payable is the check that an invoice agrees with the purchase order that authorised the spend and the receipt that proves the goods or services arrived. Three documents, one comparison, and a surprising amount of argument about whether it is worth the effort. The case for it is simple: without the order you are paying for something nobody approved, and without the receipt you are paying for something that may never have turned up. The case against is that it only works where orders and receipts actually exist, which in many small businesses is a minority of spend. This page is what each document proves, what the match actually compares, and when the check earns its cost.
What each of the three documents proves
The purchase order proves somebody with authority agreed to buy it, at a price. The goods receipt proves it arrived, in a quantity. The invoice is the supplier's claim to be paid. Matching them is how a business proves it is paying for something it ordered and received, which is exactly the assertion an auditor tests.
What the match compares in practice
Supplier, quantity and price, within a tolerance you set. Tolerances matter more than people expect: too tight and every rounding difference becomes an exception for a person to clear; too loose and the control stops operating. Start tight, measure the exceptions, and widen deliberately.
When it is worth the cost
Where goods are ordered and received it is close to free once set up. Where the spend is services with no order and no receipt, three-way matching cannot run and pretending otherwise just creates exceptions. Those invoices need a different control, usually approval by the person who commissioned the work.
Questions people ask about 3 way matching in accounts payable
Is 3 way matching a requirement?
Not a legal one. It is a widely used control, and where it operates consistently an auditor can test a sample rather than investigate. Whether you need it depends on your spend mix and what other controls you have.
What happens when the three do not match?
It becomes an exception with an owner, not an invoice that waits. The commonest causes are a price change since the order, a partial delivery, and a quantity typed wrong on one of the three.
Can this run automatically?
The comparison can. The judgement about what to do with a mismatch should not, because that is where an automated rule quietly approves something a person would have queried.