Three-Way Matching in Accounts Payable: How It Works and How to Automate It

Three-way matching is the accounts payable control that compares a supplier invoice with the purchase order and the receiving record before the invoice is approved for payment. It checks that the company pays only for goods it ordered and actually received, at the price it agreed. If quantity and price agree across all three within the company's tolerances, the invoice is paid; if they do not, it is held as an exception until someone resolves the difference.

This guide explains how a 3 way match works, how it compares with two-way and four-way matching, what tolerances are, where matching gets hard in manufacturing, how ERPs such as Epicor Kinetic handle it, and what to measure once it is automated.

How three-way matching works

A three-way match runs line by line. For each invoice line, AP finds the purchase order line it bills and the receipt lines recorded against that PO line, then checks three things:

• Item. The invoice line names the same part or service the purchase order line was raised for, whatever part number the supplier prints.
• Quantity. The quantity invoiced is no more than the quantity received and not yet billed. Billing against the order quantity instead of the received quantity is how companies pay for goods that never arrived.
• Price. The unit price invoiced agrees with the price on the purchase order, in the same unit of measure.

Header checks sit alongside the line checks: the right supplier, the right currency, a supplier invoice number that has not been entered before, and a total that agrees with the lines plus tax, freight and other charges. When every line matches, the invoice is ready to post and go into the payment run. When a line does not, the invoice waits.

Two-way vs three-way vs four-way matching

The number of "ways" is the number of documents compared. More documents give more control and more exceptions, so most companies use different levels for different kinds of spend.

Two-way matching protects price and quantity against the order but cannot tell whether anything arrived. Three-way matching closes that gap, which is why it is the standard control for physical goods. Four-way matching adds the inspection result, so goods that were received but rejected, or still sitting in inspection, are not paid for. In an ERP that records inspection as part of receiving, four-way matching is often a three-way match against the quantity that passed inspection.

A worked example

A purchase order line orders 100 brackets at $10.00 each. The dock receives 80; the rest is back-ordered. The supplier then invoices the full 100 at $10.50.

A two-way match would catch the price but pass the quantity, because 100 were ordered. A three-way match catches both. What should happen next:

• Quantity. Bill the 80 that were received. The remaining 20 are matched later, when they arrive and are received, either on this invoice (held until then) or on a corrected invoice. Most companies ask the supplier to invoice only what has shipped.
• Price. Check whether the price change was agreed. If buying accepted $10.50, the purchase order is updated and the line matches; if not, AP pays $10.00 and asks the supplier for a credit or a corrected invoice.
• Record. Whatever the decision, it is written down against the invoice, so the next person, and the auditor, can see why it was paid as it was.

Tolerances

A tolerance is the difference a company is willing to accept without stopping the invoice. Without one, a one-cent rounding difference on a unit price holds the invoice like a real overcharge.

• Price tolerance. Usually a percentage of the unit price, an amount per line, or both (for example, the lower of 2% and $50 per line).
• Quantity tolerance. A percentage or a number of units, mostly for goods sold by weight or length, or where suppliers routinely ship slightly over.
• Total tolerance. A cap on the difference across the whole invoice, so many small accepted differences cannot add up to a large one.

Tolerances are a policy decision for the controller, and a software default is rarely the right answer. Too tight and AP spends its days clearing pennies; too loose and overbilling is paid automatically. Many companies set different tolerances by supplier, commodity or invoice value, and review them once they can see how many exceptions each band produces. A tolerance should also be one-sided where it makes sense: an invoice under the order price rarely needs to stop.

Where matching gets hard in manufacturing

Textbook three-way matching assumes one PO line, one receipt and one invoice. Manufacturing rarely looks like that.

Partial shipments and several receipts per PO line

A PO line for 1,000 pieces arrives in four deliveries over six weeks, each with its own packing slip and receipt. The invoice may bill one delivery, several, or all of them. Matching has to find the right receipt lines, which means reading the packing slip numbers the supplier quotes on the invoice and checking the quantity against what has been received and not yet billed.

One receipt billed across several invoices

The reverse also happens: one receipt of 500 is billed on two invoices of 300 and 200, or a supplier invoices weekly against a blanket order. Each invoice must draw down the received quantity so the same receipt is never paid twice. The check is against what is left to bill on each receipt line.

Purchase units and stock units

You buy steel by the pound and stock it by the bar, buy fasteners by the box of 100 and stock them by the each, or the supplier prices per thousand. The PO, the receipt and the invoice may each state the quantity in a different unit. A match that compares 10 boxes with 1,000 each reports a 99% shortage. Quantities and prices have to be compared in the unit each document states, with the ERP's conversion for that part, and never by assuming a default unit.

Supplier part numbers

Suppliers invoice under their own part numbers and descriptions. Matching depends on the supplier part cross-reference kept in the ERP, or on the PO line reference the supplier prints, to tie the invoice line to your part.

Freight and miscellaneous charges

Freight, fuel surcharges, tooling, setup, expediting and certification fees appear on the invoice and often on no PO line. Some were agreed on the purchase order as charges, others were not. Each needs a rule: match to the PO charge where one exists, accept up to a limit, or route to buying for approval.

Price changes after the purchase order

Metals surcharges, annual price increases and quantity-break pricing all mean the invoice price can be legitimate and still differ from the PO. The fix is upstream: update the purchase order when the price is agreed, so the match compares against the price the company actually accepted.

Services and non-stock lines with no receipt

Calibration, maintenance, outside processing and subscriptions often have no receipt at the dock. These lines are two-way matched against the PO, or confirmed by the requester, so they do not sit forever waiting for a receipt that will never be recorded. Outside processing usually does produce a receipt when the parts come back, and should be three-way matched like material.

What to do with exceptions

An exception is an invoice line that failed the match. The common ones, and who usually resolves them:

• Received less than invoiced. Wait for the receipt, ask receiving to check whether a delivery was missed, or ask the supplier for a corrected invoice.
• Price over the order. Buying confirms whether the price was agreed and updates the PO, or AP short-pays and requests a credit.
• No purchase order or wrong PO. AP asks the requester or the supplier for the right PO number.
• Unit of measure difference. Check the part's conversion and the supplier's pricing unit before treating it as a quantity or price difference.
• Duplicate invoice. Same supplier, same invoice number or same amount and date: reject it before it is paid twice.

Each exception should have an owner, a reason code and a note on the invoice. Reason codes turn the exception queue into a report: if most exceptions are price differences from three suppliers, the fix belongs in purchasing.

How ERPs do three-way matching

Most ERPs used by manufacturers support two-way and three-way matching and keep the received and invoiced quantities on each PO line; many also let AP set tolerances and hold invoices that fall outside them. The matching itself is reliable once the invoice is in the system; the work is getting the invoice in, line by line, against the right PO lines and receipts.

In Epicor Kinetic, AP invoices for received goods are entered in AP Invoice Entry against the supplier's received lines: AP selects the receipts or packing slips the invoice bills, and the invoice lines are drawn from those received lines, so the quantity billed is tied to what was received and not yet invoiced. A price that differs from the purchase order shows as a variance against the order price. Non-stock lines and services can be invoiced against the purchase order or as miscellaneous lines. Our guide to automating Epicor AP Invoice Entry covers the screen in depth.

How automation helps

Three-way matching is mostly a reading and lookup problem: read the invoice, find the supplier, find the PO lines and receipts it bills, compare quantity and price, and write down the differences. Automation helps at each part of that.

• Capture. Read invoices in whatever format they arrive, including scans, emails and spreadsheets, without per-supplier templates.
• Lookup. Find the supplier, the purchase order lines, the receipts and the supplier part numbers in the ERP, and pick the receipt lines that still have quantity left to bill.
• Comparison. Compare every line on quantity and price in the units the documents state, and show each difference on the line where it occurs.
• Routing. Send clean invoices straight to posting under the company's approval rules and exceptions to the person who owns them.

Receipts matter as much as invoices. A three-way match is only as good as the receiving record, and invoices that arrive before the receipt is entered become exceptions for no reason. Automating receipt entry from packing slips shortens that gap. See packing slip automation.

What to measure

• First-pass match rate. Share of invoices, or invoice lines, that match on the first attempt with no one touching them. The headline measure of how well the process works.
• Exception rate. Share of invoices held for an exception, broken down by reason code and by supplier. This tells you where the fixes are.
• Exception resolution time. Time from an exception being raised to the invoice being released, by reason. Long resolution times usually point to an owner outside AP, such as buying or receiving.
• Invoices received before the receipt. Often the largest single cause of exceptions, and a timing problem that receiving can fix.
• Duplicate and overpayments caught. The control's value, in invoices and amounts stopped.

How Fluent fits

Fluent is AI agents that read business documents and draft the transaction in the ERP for a person to review. Its AP Invoice Entry agent reads supplier invoices in any format and drafts the invoice in Epicor Kinetic's AP Invoice Entry, matched as follows:

• Supplier. Matched by name and tax ID. If no supplier matches, the invoice is drafted with a note of what was searched and waits for a person.
• Lines. Matched to the purchase order and receipts, with two-way matching for lines that bill the order and three-way matching for lines that bill received goods. Parts are matched by the supplier's own part numbers.
• Quantity. Checked against what is left to bill on the receipt, so a receipt already invoiced is not billed again.
• Price. Checked against the purchase order.
• Units. Read as the document states them, never assumed.
• Differences. Every difference is shown on the line where it occurs, so the reviewer sees the exception and the reason together.

Nothing posts until a person processes the draft. An approval workflow routes each document to the people who sign off on it, with thresholds such as an amount or a price variance deciding who reviews what. Every field read and every decision is recorded on the document. Receipts come from the Receipt Entry agent, which drafts receipts from packing slips, so the receiving record the match depends on is in Epicor sooner.

Fluent connects to Epicor Kinetic's REST API from outside, with nothing installed inside Epicor, and is offered for other ERPs too. It does not pay suppliers: payment stays in your ERP and bank process. For a comparison with other tools, see the best AP automation software for manufacturers.

See it on your own invoices

Send a few real supplier invoices, including a partial shipment and a price difference, and read the draft Fluent produces in AP Invoice Entry. Start with AP automation, check pricing, or book a demo.