The Three-Way Match, Step by Step

The control in one sentence

Before an invoice is paid, three independent documents must agree: what you ordered, what arrived, and what you are being billed for. If all three line up, the invoice pays automatically. If they do not, a human looks at it.

That is the whole mechanism. Its power comes from the independence — the three documents are created by three different people at three different moments, and collusion between all of them is a far higher bar than a single person approving their own paperwork.

The three documents

The goods receipt is the one businesses skip when they are in a hurry, and it is the one that carries most of the control value. Without it you are matching the supplier's invoice against your own order — two documents that describe intentions, neither of which is evidence that anything arrived.

Why it exists

Two distinct problems, and it is worth separating them because they call for different tolerances.

The first is fraud. Without a receipt step, an invoice from a supplier who delivered nothing is indistinguishable from an invoice from a supplier who delivered everything. Fake-supplier schemes are among the most common forms of procurement fraud precisely because they need no accomplice in the warehouse.

The second, far more frequent, is ordinary error. Suppliers bill the quantity ordered rather than the quantity shipped. Prices move between order and invoice. A delivery arrives short and nobody tells accounts payable. None of this is malice, and all of it costs money that is very hard to recover once paid.

Walking a match

A concrete case. You order 500 units of a component at 12.00 each — a purchase order of 6,000.00.

1. The supplier ships 480 units. The warehouse counts them in and raises a goods receipt for 480.
2. The supplier invoices for 500 units at 12.00 — 6,000.00, because their system billed the order, not the shipment.
3. The match compares all three. Ordered 500, received 480, invoiced 500. Quantity mismatch of 20 units.
4. The invoice is held. Accounts payable raises a query for 240.00, or the system posts a 480-unit match and leaves 20 units open on the order.

Without the receipt step you pay 6,000.00 for 5,760.00 of goods, and the 240.00 is gone. At one invoice it is a rounding error. At four hundred invoices a month it is a line item.

Tolerances, and why they are necessary

A strict match blocks on any difference at all, which sounds prudent and fails in practice. Bulk commodities arrive within a percentage of the ordered weight. Currency rates move between order and invoice. Rounding on unit prices produces totals that differ by a few cents. If every one of those stops an invoice, accounts payable spends its month clearing exceptions that are all fine, and starts approving them without looking — which removes the control more effectively than not having it.

So matches are configured with tolerances, usually on both quantity and price, and usually as whichever of a percentage or an absolute cap is smaller:

• Quantity tolerance: accept a receipt within, say, 2% of the ordered quantity, or 5 units, whichever is less.
• Price tolerance: accept a unit price within 1% of the order price, or 0.50, whichever is less.
• Total tolerance: a ceiling on the invoice value regardless of the line-level outcome, so many small variances cannot add up to a large one.

Where it legitimately breaks

Four cases where the match fails and nothing is wrong. Each needs a decided answer, or your exception queue fills with them.

Partial deliveries. One order, three shipments, three invoices. The match has to work line by line and keep a running received-and-invoiced quantity per line, not per document.

Freight and incidentals. The invoice carries a delivery charge that appears on no purchase order and in no receipt. Either the order has to anticipate it as a line, or the system needs a defined class of non-matched charges with their own approval.

Over-delivery you want to keep. The supplier ships 510 against an order of 500, and it is cheaper to keep them than return them. Someone with authority has to accept the extra and amend the order.

Services. There is nothing to receive. A consultancy invoice has no goods receipt note, so it drops to a two-way match against the order, or to a service-entry confirmation from whoever commissioned the work.

Who may override, and on what

Every match system needs an override, because some exceptions are genuinely fine and someone has to say so. The override is also the point where the control can be dismantled, so it is worth designing rather than inheriting.

The rule that does most of the work: whoever raised the order may not be the person who releases its invoice for payment. If one person can create a supplier, raise an order, receive it and approve payment, no amount of matching helps — the three documents are independent in form only.

• Tiered thresholds. Accounts payable clears variances under a small cap; a manager clears mid-range; anything large goes to the budget holder who committed the spend.
• Reason codes, not free text. An override recorded as "agreed with supplier" is unreportable. A short code — price increase accepted, short delivery accepted, freight not ordered — turns the exception log into something you can analyse.
• A supplier-change freeze. Bank detail changes on a supplier record should suspend payment until verified out-of-band. Invoice redirection fraud targets exactly this gap, and it defeats a working three-way match completely.

What good looks like in numbers

A match process is measurable, and the measures tell you whether the tolerances are set sensibly or whether people are just clearing the queue.

A first-pass rate near 100% is not the goal and is usually a warning. It normally means tolerances are wide enough that nothing is being caught — the control is running, reporting success, and stopping nothing.

The most useful report is not the exception queue but the recurrence list: which suppliers, and which variance reasons, appear month after month. Those are fixable at source — a price list that was never updated, a unit of measure mismatch, a supplier who always bills ordered rather than shipped. Each one removes a recurring exception permanently, rather than clearing it again.

Two-way and four-way

A two-way match compares order and invoice only. Appropriate for services and for low-value consumables where a receipt step costs more than the risk it removes. It is a real control — it catches price and quantity differences against what was agreed — but it cannot tell you whether anything arrived.

A four-way match adds an inspection or quality certificate between receipt and payment: goods arrived, and were accepted. Standard for regulated materials, for anything with a specification that can be failed, and for suppliers on probation after quality problems.

The right answer is usually all three, routed by category and value. Three-way as the default, two-way for services and small consumables, four-way for anything where receiving the goods and accepting them are genuinely different events.