Three-way match
Checking the purchase order, the goods receipt note and the supplier's invoice against each other before a bill is approved for payment.
Three-way match is the discipline of not paying a bill until three documents agree: what you ordered, what you received, and what you are being billed for.
What each document answers
The purchase order answers "was this authorised, and at what rate". The goods receipt note answers "did it actually arrive, and in what condition". The invoice answers "what is being claimed". A payment made on the invoice alone answers only the last one.
The differences you are looking for
A rate charged above the agreed rate. A quantity billed above the quantity received. Items on the bill that were never ordered. Tax charged at a rate that does not match the HSN code. Freight added that the terms said was included.
It is not bureaucracy for a small business
Even a shop buying from ten suppliers a month loses real money to quiet rate creep and short deliveries. The check takes two minutes per bill when the three records sit in one place; it takes an afternoon when they are in a file, a diary and a chat thread.
How KillStock handles it
On the Growth plan and above, goods receipts are recorded against the purchase order, and a photographed supplier invoice has its lines, taxes and totals extracted and reconciled to that PO — so the comparison is on screen instead of on paper.
A common mistake
Matching only on the total. Two errors that cancel out — an over-billed rate on one line and a short quantity on another — pass a total check and still cost you money.