Invoice matching
Invoice matching is the control step that verifies a supplier invoice against other documents before payment is approved. Two-way matching compares the invoice to the purchase order, three-way matching adds the goods receipt, and four-way matching adds inspection or quality acceptance. Lines that agree within set tolerances post automatically; mismatches become exceptions that must be investigated and resolved before the invoice can be paid.
Examples
Three-way catch: An invoice bills 5,200 brackets at $1.18 each; the PO says 5,000 at $1.12 and the receipt shows 5,000 received. Matching flags both a 5.4 percent price variance and 200 units billed but never received, and the buyer recovers $536 before payment instead of chasing a credit afterward.
Four-way hold: A lot of 800 machined housings matches the PO and the receipt, but incoming inspection rejects 60 units on a bore tolerance. Under four-way matching, payment releases for 740 units; the 60 rejects route to a debit memo and a corrective action request.
Definition
Matching exists to stop three failure modes: paying for items never ordered, paying for items never received, and paying a price never agreed. Each invoice line is compared to the purchase order for price and quantity; a three-way match also checks billed quantity against the goods receipt. Four-way matching, used for inspected or safety-critical parts, holds payment until quality acceptance is recorded.
Tolerances decide how strict the check is. A typical setup allows a small price variance, capped as a percentage and as an absolute dollar amount, whichever is lower, plus a modest quantity overage to absorb rounding and partial shipments. Set tolerances too tight and accounts payable drowns in trivial exceptions; set them too loose and price creep clears unexamined. The defensible way to set them is from data: pull six months of variances and find where real money leaks.
Exceptions deserve root-cause fixes, not heroics. Recurring price mismatches usually mean negotiated prices never reached open POs; quantity mismatches usually mean receiving posts late. Clearing those upstream problems is what lets invoice automation reach high touchless rates instead of becoming a faster exception generator.