Invisible supplier overpayments: how to detect them
SMEs that receive 100-2,000 invoices/month lose between 4 and 9% of their spend to invisible supplier overpayments. It is not fraud. It is not malice. It is the mathematical consequence of reconciling invoices by totals instead of line by line. Here we explain how those overpayments are generated, how to detect them before paying and how to recover the money.
What is an invisible overpayment
An invisible overpayment is any euro you pay a supplier above what was actually agreed and delivered, without your system detecting it. Three sources:
- Invoiced price above the price on the PO. Price change not communicated, miscoding, unfavourable rounding.
- Invoiced quantity above the quantity received on the delivery note. Broken goods returned, partial receipt not updated.
- Duplicate invoice. The same cost paid twice because the supplier resends it or due to a team error.
Why they become invisible
Three mechanisms keep these overpayments from being detected:
1. Matching by totals, not by lines
If you compare invoice total vs PO total and the difference falls within your tolerance margin, you approve. But two errors on different lines can offset each other in the total. Here we go through the numbers.
2. Global tolerance, not per line
A 2% tolerance applied to the invoice total allows large variances on individual lines. A 50 EUR variance on a 50 EUR line is 100% on that line, but only 1% on a 5,000 EUR total.
3. Volume without time
An SME with 600 invoices/month and 80 suppliers cannot review every document line by line manually. The statistics work against you: 4-9% always slips through.
The actual numbers
| SME volume | Overpayment low rate (4%) | Overpayment high rate (9%) |
|---|---|---|
| 200 invoices/month, average ticket 1,500 EUR | ~12,000 EUR/month | ~27,000 EUR/month |
| 500 invoices/month, average ticket 1,500 EUR | ~30,000 EUR/month | ~67,500 EUR/month |
| 1,000 invoices/month, average ticket 1,500 EUR | ~60,000 EUR/month | ~135,000 EUR/month |
Not all those overpayments are at 100% of the amount. Assuming that when there is an overpayment the average amount is 5-10% of the affected invoice value, real annual loss is in the order of 4 to 6 figures depending on volume.
Market estimates based on IOFM and Ardent Partners benchmarks for companies with non-automated AP. Your actual figure depends on process rigor, industry and specific suppliers.
How to detect them before paying
Three operational rules:
1. Compare unit prices pre-VAT
Invoice vs PO, line by line. No VAT, no rounding, no global tolerance.
2. Compare quantities vs delivery note, not vs PO
The PO says what you wanted. The delivery note says what you actually received. If you pay by what is invoiced without checking against the delivery note, you pay for what you did not receive.
3. Per-line tolerance (OR mode)
Recommended: 2% or 1.50 EUR per line, whichever is more permissive. Configurable per supplier or category. If a line exceeds tolerance, raise an exception.
How ininvoice automates it
- Captures every invoice from the supplier email (Gmail/Outlook).
- Extracts line by line (OCR/IDP, FacturaE, Factur-X).
- Looks up the PO via fuzzy matching.
- Cross-checks unit price pre-VAT against the PO.
- Cross-checks quantity against the delivery note.
- Applies tolerance configurable per line.
- Detects duplicates with multi-criteria signals.
- If there is an exception, routes it to the right owner. The invoice is not approved.
If all lines reconcile, it exports to your ERP ready to book. If a line fails, it shows you exactly which line, how much overpayment there is and who to route the conversation with the supplier to.
Recovering past overpayments
If you have spent time without line-by-line matching, you have probably accumulated overpayments pending recovery. Reviewing the history is useful to:
- Identify invoices with variance not detected at the time.
- Raise the claim with the supplier.
- Negotiate a credit note or a credit on future invoices.
In distribution profiles with 6 months of history, it is not unusual to find 4-5 figures of recoverable overpayments. Estimate based on industry benchmark.
Do you suspect you are overpaying your suppliers?
15 min with the team. I will show you how your real overpayments are detected with your own invoices. Book your demo.
Frequently asked questions
- How do I know if I have overpayments?
- If your current reconciliation is by totals (invoice vs PO) or if you do sample review instead of exhaustive, you almost certainly have them. The question is not whether you have them, it is how much.
- Is it legal to claim overpayments back from the supplier?
- Yes. If the invoice exceeds the agreed PO or the delivery note received, the supplier is required to issue a credit note or a corrective invoice. Your tax adviser can guide you on specific cases.
- Is it not the supplier's problem, not mine?
- Yes, but the money is yours. And you are the one losing it, not the supplier. The responsibility to detect it is on whoever pays.
- How much does it cost to automate detection?
- ininvoice plan: 249 EUR/month up to 300 invoices/month. The overpayment detected in the first month usually exceeds the annual cost of the software.