What to do when an invoice and purchase order do not match
The invoice and purchase order do not match. The supplier may have used a different price, billed a different quantity or referenced an older order revision. Before treating the difference as an error, compare the same item on the same basis and gather the record that explains the change.
You need the supplier invoice, the applicable purchase order and a clear list of differences. The result should help the buyer or finance reviewer decide what to query and whether the invoice can continue through approval.
Start with the correct purchase order
An invoice can appear wrong when the reviewer is using an obsolete PO. Check the order number and revision, then look for an approved amendment or agreed additional charge. An email mentioning a change is useful context, but your process determines whether it constitutes an approved amendment.
Confirm the supplier entity and currency as well. Similar trading names, multiple supplier accounts and foreign-currency orders can create apparent matches that do not belong together.
Keep the original invoice and PO with the review. If you normalize references for matching, preserve the original values so the next reviewer can find the same item without repeating your search.
Compare each value on the same basis
| Field | Check | Common explanation to investigate |
|---|---|---|
| Item reference | Same product or service line | Different descriptions or supplier codes |
| Quantity | Same unit of measure | A box contains several units |
| Unit price | Same currency and pricing basis | Revised price, discount or surcharge |
| Line amount | Quantity and applicable price agree | Rounding or a line adjustment |
| Tax and delivery | Compared separately where relevant | One displayed total includes additional charges |
| Document total | All lines and adjustments included | A missing page or summarized charge |
Check each explanation against evidence. Do not assume that an equal total proves every line matches: one overcharge and one undercharge can cancel out. Conversely, a small total difference may arise from rounding rather than a different agreed price.
A worked invoice and purchase-order mismatch
This example uses fictional figures. The PO orders 100 units at €12 each, for €1,200 before tax. The invoice bills 100 units at €14 each, for €1,400 before tax.
The quantity agrees. The unit-price difference is €2, and the line difference is 100 × €2 = €200 before tax. The useful exception is therefore a price difference, not a quantity discrepancy.
| Record | Quantity | Unit price | Line total before tax |
|---|---|---|---|
| Purchase order | 100 | €12 | €1,200 |
| Invoice | 100 | €14 | €1,400 |
| Difference | 0 | €2 | €200 |
Ask whether an approved price amendment explains the €14 rate. If it does, retain that record with the review. If it does not, request a corrected invoice or a supplier explanation. The example establishes the difference; it does not establish the commercial answer without the supporting agreement.
Check quantities and units before escalating
A PO may list 10 boxes while an invoice lists 100 pieces. If each box contains 10 pieces, the quantities may represent the same delivery. Compare the unit conversion and price basis together; a price per box cannot be compared directly with a price per piece.
Service invoices require similar care. A monthly fee, day rate and hourly rate are different bases. Confirm the service period and whether the line describes an agreed fixed amount or actual usage.
If the invoice refers to several orders, separate the relevant lines before concluding that one PO is missing quantities. Keep any unallocated line visible. Avoid forcing a match merely because the supplier and total seem plausible.
Know when a delivery record is necessary
Invoice-to-PO matching checks the bill against the order. It does not prove what was received. If quantity received is the concern, use the invoice, PO and delivery note together.
For example, an invoice and PO may both show 100 units while the delivery note shows 80. There is no two-way quantity difference, but the missing delivery evidence matters to the next decision. Follow the three-way matching guide for partial deliveries for that situation.
Oracle's matching-level documentation distinguishes these checks. Arthur & Co's file-based workflows provide comparisons and exceptions; they should not be confused with an ERP's automated matching holds or approval engine.
Record a discrepancy that another person can resolve
Include the invoice number, PO number and revision, item reference, both source values, calculated difference and the evidence still needed. Name the person responsible for the next step.
A concise supplier query might read: “Invoice INV-204 bills 100 units at €14. PO-72 revision 2 lists 100 units at €12. Please confirm the approved amendment supporting the €200 difference before tax, or provide a corrected invoice.”
This is easier to answer than “your invoice is wrong.” It also allows the buyer to identify an internal PO update that finance has not yet received.
Keep the result of the query with the source pack. A telephone explanation should be recorded through your normal process so the next reviewer does not face the same unexplained difference.
Use the workflow for a checkable first comparison
Arthur & Co's invoice-to-PO matching workflow compares the two records and exposes quantities, prices, amounts and header differences. Check the extracted values against the documents, especially where a scan or unusual layout makes a field uncertain.
The free entry needs both records and email verification. It lets you inspect the result before choosing paid use for repeat checks and saved history. The workflow page explains current inputs and workload allowances.
You decide whether the invoice can proceed through your approval process. The workflow identifies differences; it does not approve or make the payment.
Finish with an explained difference
Close the issue only when the records agree or the difference has a supported explanation and a recorded decision. Keep unresolved delivery or credit questions visible rather than hiding them inside a generic approval note.
If these checks recur across the team, use the small-team AP automation guide to plan a focused pilot and evaluate review quality.