Invoice does not match the PO: step-by-step protocol

Friday, 6:05 pm. You open the last supplier invoice and the total does not match. EUR 312 difference. The buyer has already left. The supplier does not answer. What do you do?

This article is the concrete recipe. If you want the maths of the calculation, see how to calculate price variance between invoice and PO.

Immediate steps when you detect the mismatch

Five actions, in this order, in less than 15 minutes:

1. Do not approve. Mark as “under review”. If it was in a batch, remove it.
2. Locate the three documents. PO, delivery note and invoice. Without all three you are flying blind.
3. Compare line by line, not by totals. Two lines can offset each other internally.
4. Record the difference in euros pre-tax. Absolute and percentage. Both.
5. Document the case. Screenshot, IDs, amount in dispute and who owns it. So you don’t start from scratch on Monday.

With that you have the diagnosis. From here you decide everything else.

Types of mismatch: price, quantity, both or totals that match

Not every mismatch is the same. The way to resolve it depends on the type:

• Price mismatch. Same quantities, different unit price. Usually a rate change not notified. Goes to purchasing.
• Quantity mismatch. Same unit price, invoiced quantity different from the one delivered. Usually a partial delivery note. Goes to the warehouse.
• Double mismatch. Price and quantity off. Two exceptions, each routed to its team.
• Totals match, lines don’t. The most dangerous case. +EUR 50 on A, -EUR 50 on C. Total 0. If you cross-check by header, it slips through without alerting.

That is why serious reconciliation is always line by line. The total never lies, but the lines do.

How to decide whether to stop the payment

Simple operating rule, OR mode (either condition triggers it):

Per-line difference	Action
< 2% AND < EUR 1.50 absolute	Approve and pay. Log but do not escalate.
> 2% OR > EUR 1.50 absolute	Stop payment. Open exception.
> 5% OR > EUR 50 absolute	Stop payment + escalate to the purchasing lead within 24h.
> 10% OR > EUR 500 absolute	Stop payment + contract review + formal supplier communication.

You don’t stop for millicents: it blocks treasury and sours the relationship. But repeated monthly EUR 50 over a year is EUR 600 that evaporate.

Cases where you do NOT stop even if the line is out

• VAT rounding. Millicents when dividing total by quantity. Royal Decree 1619/2012 regulates the breakdown.
• Documented contractual adjustment. Signed addendum or index-based escalation not reflected on the PO.
• Early-payment discount. Invoice arrives gross and the discount is applied at payment.

Supplier communication template

Editable text. Replace the brackets and send:

Subject: Invoice [Number] — mismatch with PO [PO No]

Hi [Name],

We received invoice [Number] dated [Date] for an amount of [EUR X].

When cross-checking against PO [PO No] we found the following
line-by-line differences (pre-tax amounts):

- Line [SKU/description]: PO [EUR X/u] x [Y units] = [EUR Z]
 invoice [EUR X'/u] x [Y' units] = [EUR Z']
 difference: [± EUR D]

Until we confirm the origin of the mismatch we are holding
the invoice under review and it will not be paid in the
scheduled run.

We need you to confirm within 48h:
1. Whether the difference is due to a rate change.
2. If yes, a copy of the rate change notice.
3. If a mistake, an estimated date for the correction invoice.

Looking forward to your reply.

Thanks,
[Your name] · [Company] · [Phone]

Pre-tax figures, concrete deadline (48h) and a closed routing. No meeting needed.

When to ask for a credit note vs a correction invoice

Common confusion. Two different artefacts under Spanish tax law:

• Correction invoice (factura rectificativa). Replaces or amends an issued invoice with an error. You request it when the mismatch is clear and the supplier acknowledges the mistake. Governed by article 15 of Royal Decree 1619/2012.
• Credit note. A document that reduces the amount without cancelling the original invoice. You request it for partial returns, post-invoice discounts or commercial adjustments.

Wrongly issued invoice → correction invoice. Correctly issued invoice but later commercial adjustment → credit note. The distinction matters for the Spanish SII system.

Response times by amount

Match urgency with the wallet. A simple policy:

Disputed amount	Max response time	If they don’t reply
< EUR 50	5 business days	Pay under protest and log it.
EUR 50-500	48 business hours	Escalate to the supplier’s sales rep.
EUR 500-5,000	24h	Call the sales lead.
> EUR 5,000	Same day	Formal written communication + block open POs.

“Pay under protest”: you pay but you formally register the dispute. That way you can claim later.

Automation: stop this fire from repeating next month

Once is bearable. Every week is not. If you receive more than 100 invoices a month, mismatches are systematic and each one costs three hours between Excel cross-checking, emails and chasing the buyer.

The alternative is touchless accounts payable: intake from Gmail or Outlook, structured reading of PDF and FacturaE, line-by-line matching with a 2% / EUR 1.50 OR-mode tolerance and differentiated routing to purchasing or warehouse. Industry averages published by IOFM place exception resolution in hours (not days) when there is automatic routing.

Real examples: three typical cases

Case 1: the supplier raises the price without notice

PO at EUR 1.00/u for 200 units. Invoice arrives at EUR 1.12/u. Difference: (1.12 − 1.00) × 200 = EUR 24. Percentage: 12%. Stop payment, escalate to purchasing, ask for a copy of the rate change notice.

Case 2: they invoice more than what was delivered

PO of 100 units. Delivery note confirms 80. Invoice shows 100. Quantity variance: (100 − 80) × EUR 5.00 = EUR 100 excess. Stop payment, verify second delivery note and request credit note or correction invoice for the 20 units.

Case 3: the total matches but the lines don’t

PO of EUR 1,000 in three lines. Invoice of EUR 1,000. Header perfect. Line A: +EUR 50. Line C: -EUR 50. If you cross-check by totals, it passes. Line by line, you detect two unannounced contractual changes and protect future margin.

15-minute checklist to resolve the mismatch

Print this. Stick it to your monitor.

1. Mark invoice as “under review” in the system. (1 min)
2. Open PO, delivery note and invoice in three tabs. (1 min)
3. Compare line by line: pre-tax unit price and quantity. (5 min)
4. Record differences in absolute euros and percentage. (2 min)
5. Classify: price, quantity, both, or totals trap. (1 min)
6. Decide according to tolerance table. (1 min)
7. If you stop payment: send template to supplier + cc internal buyer. (3 min)
8. Document case in system with screenshot and references. (1 min)

Fifteen minutes. If it takes longer, the problem is not the case, it is the tool.

Frequently asked questions

What do I do if the invoice is for less than the PO?

Same as if it were more: document and open exception. It could be a promotional discount or a partial delivery note.

Is it legal to stop payment if I dispute the invoice?

Yes. Spanish Law 15/2010 against late payments sets maximum terms but does not force you to pay invoices under dispute. Communicate the reason formally.

How long do I have to claim against the supplier?

Article 15 of Royal Decree 1619/2012 allows correction invoices up to 4 years. In practice, claim as soon as you detect the error.

And if the supplier does not reply on time?

Sales escalation. If they still don’t reply, pay under protest or block open POs. For large amounts, registered postal notification.

Do I have to redo the Spanish SII reporting if I request a correction invoice?

Yes. The correction invoice generates a new SII record that replaces or complements the original.

What if the mismatch repeats every month with the same supplier?

It’s a pattern. Review the contract, current rate and master data. Usually it is outdated data on your side or undisclosed supplier pricing.

Three things to remember

1. The total never lies, but the lines do. Always compare line by line, pre-tax. The totals-match trap is the most expensive.
2. Tolerance: 2% OR EUR 1.50 OR-mode per line. Don’t stop for millicents. Don’t approve euros that pile up over a year.
3. Traceable documentation from minute one. Screenshot, template, deadline, escalation. Without paper trail, no claim is possible.

If you want to see how this looks on your own invoices, try ininvoice. You can also check the pricing and features in detail.

Related content

• Price variance between invoice and PO: how to calculate it
• Three-way matching: cross-check invoice, PO and delivery note line by line
• Touchless accounts payable: what it means and how to measure it
• Invoice and delivery note reconciliation