AI Invoice Matching: Invoice, Delivery Note and PO

Three documents, one check: why matching matters

The purchase order shows what you asked for, the delivery note shows what arrived and the invoice shows what you will pay. No payment should go out until all three agree. This check is called three-way matching.

AI speeds this comparison up. It lines up long item lists side by side and lists the differences. But it can sometimes mark a match as "OK" when there is none.

So the aim is to use the AI's speed while tying every line to a document. Speed comes from the AI; accuracy comes from your check. The payment decision rests only on lines whose evidence you have seen.

A matching error may look small, but its effects can grow. Recovering an overpayment takes time. An underpayment strains the supplier relationship for no reason.

Giving the AI the documents correctly

Give the three documents separately and by name. For example, label them "Document A: PO", "Document B: Delivery note" and "Document C: Invoice". The AI then does not mix up which fact came from where.

In scanned documents, fill in unreadable fields yourself or leave them blank. The AI must not guess a figure it cannot read. Say this clearly in the prompt.

Ask for the output as a table. Put the PO, delivery note and invoice values for each item in separate columns. The last column should say "matches", "gap" or "no evidence".

Share documents only through a tool your company allows. That may be ChatGPT, Copilot or your company's own chat tool; company policy sets the rule.

Catching amount, quantity and date gaps

Gaps most often appear in three places: unit price, delivered quantity and date. With a partial delivery, the delivery note can show fewer units than the PO. The invoice, however, is sometimes raised for the full order.

Check the AI's totals yourself as well. Multiply quantity by unit price and compare the result with the invoice line. Verify VAT and discount lines one by one.

Put the dates in order too. If the invoice is dated before the delivery note, there should be a reason. If there is none, flag the line as a question.

Compare units and currency as well. If the PO says "box" and the delivery note says "piece", equal numbers can mean different quantities. For invoices in foreign currency, check the exchange rate and its date too.

Flagging lines without evidence

AI sometimes adds a fact to its summary that is in no document. A sentence like "the missing units will arrive in the next shipment" sounds reasonable. But if no document says it, it has no basis.

For every "matches" result, see the matching value in all three documents with your own eyes. Mark any line you cannot trace as "no evidence". That line does not go forward for payment approval.

Apply the same care to confident wording. Sentences like "the supplier confirmed" or "the return was accepted" need a written source. Without one, they stay out of the table.

The short example below shows how one fluent sentence can hide two separate errors.

Keeping approval with the finance owner

The table the AI prepares is a working paper, not a payment approval. The finance owner decides how each gap is resolved. The AI shows the gap; the responsible person chooses the fix.

When you send the table for approval, add a clear note. State briefly which lines matched, which showed a gap and what information is expected from whom. Keep the question for the supplier ready as well.

The finance team then sees everything it needs for the decision on one page. Responsibility stays clear and the record is ready for audit.

The method also saves time on monthly routines. Keep the prompt and table as templates and swap in only the documents each period. Everyone on the team then works in the same format.

Checklist

1. I gave the three documents in full, each under its own label.
2. No unreadable field was left for the AI to guess.
3. I verified quantity × unit price for every item myself.
4. I checked VAT, discount and total lines separately.
5. I compared the order of invoice and delivery note dates.
6. Every statement without a source document is flagged "no evidence".
7. I sent the table to the finance owner with a clear note.