## TL;DR
The invoice bills 20 units that were never received, so the match is doing its job. Pay for the 480 received, keep the 20-unit balance open on the PO as a short shipment or a pending delivery, and get the vendor to credit or ship the balance. Do not override the match to pay 500 against a 480 receipt; that converts a vendor error into your loss if the balance never arrives.

```text
three-way match failed: PO 45821 quantity 500, received 480, invoiced 500
```

## Use this when
- PO 45821 shows ordered 500, goods receipt 480, invoice 500.
- The match exception is quantity-based, not price-based.
- Receiving records show no second delivery for the 20 units.

## Not for this skill when
- Receiving confirms 500 arrived but the receipt was keyed as 480. Correct the receipt, not the payment.
- The 20 units are a planned partial shipment arriving later under the same PO. Then set the invoice to partial-pay status instead of treating it as an exception to clear.

## Steps
1. Pull the PO, the goods receipt, and the invoice lines for 45821 and confirm quantities per line, not just in total. Verify: the 20-unit shortfall sits on a specific line
2. Ask receiving to confirm no second receipt, damage hold, or unposted delivery note covers the 20 units. Verify: receiving confirms the physical position in writing
3. Check the vendor invoice and any credit or short-ship note for acknowledgement of the shortfall. Verify: the vendor position on the 20 units is documented
4. Approve payment for 480 at the PO price and place the invoice balance on hold against the open PO quantity. Verify: AP pays the received quantity only and the PO stays open for 20
5. Resolve the balance with the vendor: credit memo for 20 or a dated delivery commitment, recorded on the PO. Verify: the PO balance has a documented outcome, not an open question

## Variant phrasings
### three way match quantity short invoice overbilled
The short-shipment phrasing.
### PO received less than invoiced match exception
Searching from the receiving side.

Compatibility: Three-way match in SAP, Oracle, NetSuite, Dynamics 365, and Coupa-style AP automation.

## Why it happens
Three-way match exists to stop payment for goods not received. A quantity exception means the documents disagree about a physical fact, and only the warehouse knows the truth. Invoice-first pressure makes overriding tempting, but the override erases the only control that connects cash out to goods in. Partial payment against the receipt preserves both the control and the vendor relationship.

## Edge cases / pitfalls
- Unit-of-measure conversions, cases versus eaches, create phantom shortfalls. Confirm both sides count in the same unit before escalating.
- If the 20 units arrived damaged and were rejected, the receipt should show a return. The match fix then follows the return paperwork.
- Repeated short ships from one vendor are a vendor performance issue; the exception report by vendor is the evidence pack.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_Xd5SO9C0DlHxcANAQb7CXg