My Client Never Received My PEPPOL Invoice: A Troubleshooting Guide for Belgian Businesses

You sent the invoice. The status in your software shows "sent." Your client calls to say they never received anything.

This is one of the most disorienting situations in the new PEPPOL reality — because the old fallback (resend the PDF, done) is no longer the right answer. With Belgium's tolerance period ending March 31, 2026, and penalties starting at €1,500 for a first offense, €3,000 for a second, and €5,000 for subsequent violations, a failed delivery is not just an inconvenience. It is a compliance risk for both parties.

This guide is not another explanation of what PEPPOL is. It is a structured diagnostic for when something has already gone wrong.

Start Here: The Delivery Verification Check

Before you do anything else, verify what actually happened on your end.

What to check in your invoicing software: - Does the invoice show a PEPPOL transmission status? Look for terms like "delivered," "acknowledged," or an MDN (Message Disposition Notification). - Is there a timestamp for when the document left your access point? - Is there a PEPPOL document ID or transmission reference you can quote?

If your software does not show delivery confirmation at all, that is already a signal. A well-integrated PEPPOL setup — like Dokus, which connects via Recommand, a certified Belgian access point — logs delivery events per invoice. If you have no record, the problem may be on your side.

If you do have a delivery confirmation, the issue is almost certainly downstream of your access point. That narrows the diagnosis considerably.

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Failure Mode 1: Your Client Is Not Registered or Not Active on PEPPOL

This is the most common failure — and the most surprising one, because senders often assume their client is on the network simply because they are a Belgian business.

What happens: Your access point looks up your client's PEPPOL ID in the SMP (Service Metadata Publisher) — effectively the PEPPOL directory. If the client has no registered endpoint, the invoice cannot be delivered. Depending on your software, this either surfaces as an error or silently fails.

How to check: 1. Go to [einvoice.belgium.be](https://einvoice.belgium.be) — the official Belgian portal maintained by FOD Financiën/SPF Finances. 2. Use the PEPPOL participant lookup to search for your client's KBO/BCE number. 3. If they do not appear, they are not yet registered.

Resolution steps: - Contact your client and ask which access point or invoicing software they use. - If they do not have one, point them to the einvoice.belgium.be onboarding resources. - In the meantime, ask whether they have a formal waiver or exception on file with FOD Financiën. - Do not simply switch to PDF email without documenting the situation — a PDF backup is only legally acceptable when your client has a documented inability to receive PEPPOL (more on this below).

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Failure Mode 2: The Invoice Arrived But Your Client Is Not Checking Their System

The invoice was delivered successfully to your client's access point. The problem is that no one on their side has looked.

What happens: Many small businesses and accountancy offices receive PEPPOL invoices into a software inbox that someone needs to actively monitor. If your client has just switched tools, if their accountant handles the inbox, or if the system requires manual approval to process — the invoice can sit unread for days or weeks.

How to diagnose: If your delivery log shows a successful transmission, this is the most likely culprit.

Resolution steps: 1. Send a brief, factual follow-up message: "I can confirm the invoice was delivered to your PEPPOL inbox on [date]. Can you check whether it appears under [pending / incoming documents]?" 2. Ask which software or access point they use. Common Belgian platforms include Isabel, Billit, Exact, or Yuki — the document may be sitting in a specific queue. 3. Suggest they contact their access point's support if they cannot locate it.

What not to do: Do not immediately send a PDF replacement. If the PEPPOL invoice is confirmed delivered, a PDF duplicate creates confusion and can lead to duplicate payment or accounting errors on their side.

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Failure Mode 3: Access Point Delivery Failure

Sometimes the problem is a genuine technical failure between access points — your document left your system but never arrived at the destination.

What happens: Access point outages, routing errors, or format validation failures at the receiving end can cause delivery to fail silently. This is less common with established access points but does occur, especially with newer or less mature integrations.

How to diagnose: - Check whether your access point logged an error or bounce notification. - Look for any error codes in your transmission log — common ones include document format validation failures (the receiving access point rejected your UBL structure). - If you use a certified access point like Recommand, they maintain transmission logs and can provide a delivery audit on request.

Resolution steps: 1. Contact your access point's support team with the transmission reference and ask for a delivery trace. 2. If a format validation error is returned, check whether your UBL document is correctly structured — in particular, whether mandatory Belgian fields (KBO number, VAT number, legal address) are present and correctly formatted. 3. If the failure is on the receiving access point side, your client's software provider needs to be involved. 4. Document the failure and the steps you took. This is relevant if the invoice's legal status is later questioned.

The Business Expert Group (BEG), which advises on Belgian e-invoicing implementation, has published guidance on handling technical delivery failures. A documented good-faith attempt to deliver via PEPPOL — with error logs — provides legal protection when delays occur for technical reasons.

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Failure Mode 4: Duplicate Sends from PEPPOL and Email Creating Confusion

You sent the invoice via PEPPOL and also emailed a PDF copy "just to be safe." Now your client has two invoices and is not sure which one is the valid document.

What happens: This is an increasingly common source of confusion as businesses transition to PEPPOL. The PEPPOL invoice is the legally valid one. The PDF is a human-readable representation but has no legal status for Belgian B2B transactions after the mandate. However, many clients' accounting staff still process the PDF out of habit.

The risks: - Your client's accountant processes the PDF and then receives the PEPPOL invoice as a "second invoice" — triggering a duplicate payment flag or a rejected VAT deduction. - The client pays the PDF version early and considers the PEPPOL invoice "already paid" — creating a matching problem in their books. - Critically: If the client processes only the PDF and ignores the PEPPOL version, their VAT deductibility for that invoice is at risk. FOD Financiën/SPF Finances can deny a VAT deduction if the invoice was not received and processed through the correct legal channel.

Resolution steps: 1. Stop sending PDF backups unless specifically requested and documented (see the section below on when PDF is acceptable). 2. If you have already sent both, contact your client explicitly: "The invoice sent via PEPPOL on [date] is the legally valid document. The PDF I sent by email is for reference only — please process the PEPPOL version." 3. Ask your client to confirm which document they have booked in their accounting system. 4. If there is a genuine duplicate booking risk, work with your client and their accountant to correct it before VAT return time.

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Failure Mode 5: Incorrect PEPPOL ID or KBO Number

Your invoice was addressed to the wrong PEPPOL endpoint — either because your client's ID was entered incorrectly, or because their KBO/BCE number in your system does not match their actual PEPPOL registration.

What happens: PEPPOL routing relies on a participant identifier — in Belgium, this is typically the KBO/BCE number formatted as a PEPPOL ID (scheme 0208 for Belgian companies). If there is a typo, a leading zero is missing, or your client registered under a different identifier format, the delivery will fail or go to the wrong endpoint.

How to check: 1. Verify your client's KBO number directly via the KBO/BCE public register at kbo.fgov.be. 2. Cross-reference the PEPPOL ID you used with their registration on einvoice.belgium.be. 3. Check whether the client registered under their VAT number (BE + 10 digits) vs. the KBO number (10 digits without prefix) — both formats appear in Belgian PEPPOL registrations, and confusion between them is common.

Resolution steps: 1. Correct the PEPPOL ID in your system before resending. 2. Issue a credit note for the incorrectly addressed invoice if it was already booked in your system. 3. Reissue with the correct identifier — do not simply resend the same invoice, as this can create document ID conflicts.

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Having the "I Didn't Get It" Conversation with Your Client

When a client says they never received your invoice, the conversation can quickly become awkward — especially if payment is already overdue.

How to frame it: - Lead with your transmission reference: "I have a delivery confirmation from [date] showing the invoice reached your PEPPOL endpoint. Can we trace where it went from there?" - Avoid framing it as their problem immediately — make it a joint investigation first. - If the client is a smaller business, they may genuinely be confused about where PEPPOL invoices appear in their workflow. Walk them through it.

What to document: - The date and time of your PEPPOL transmission - The delivery status from your access point - Any correspondence about the issue - The resolution steps you both agreed on

This documentation matters if the invoice becomes a collection issue or if the timing is later questioned by FOD Financiën during a VAT audit.

The KVABB concern: The Belgian association KVABB raised formal concerns with the minister about exactly this kind of situation — businesses in good-faith compliance struggling with technical delivery failures and unclear legal standing. The official guidance reinforces that documented good-faith delivery attempts are taken into account.

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When a PDF Backup Is Legally Acceptable

There is a narrow window in which sending a PDF is still the right answer — but the conditions matter.

Acceptable situations: - Your client has formally notified you that they cannot receive PEPPOL (e.g., they have a documented exception on file with FOD Financiën, or they are a foreign entity outside the PEPPOL network). - There has been a confirmed, documented technical failure on your access point's side, and you have notified the relevant parties. - Your client is a non-Belgian company with no Belgian PEPPOL registration.

Not acceptable situations: - You "just want to be safe" and the PEPPOL invoice was delivered successfully. - Your client prefers PDF for internal processing reasons. - You are in a hurry and PDF is faster.

When a PDF is justified, send it with an explicit note that it is a backup only and that the legally valid invoice was transmitted via PEPPOL. Keep that correspondence.

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A Note on VAT Deductibility

This is the penalty that often gets overlooked. The headlines focus on the sender's fines — €1,500, €3,000, €5,000 — but the receiving side has its own exposure.

If your client receives a PDF invoice (when they should have received a PEPPOL-compliant one), and processes the PDF for VAT deduction purposes, FOD Financiën/SPF Finances can reject that deduction. This means your client loses the VAT amount entirely — not just a fine, but real cash.

This creates a mutual incentive to solve delivery problems properly. When you explain to a reluctant client why they need to get their PEPPOL inbox sorted, their VAT deductibility is a more compelling argument than your compliance obligations.

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Building a Reliable Delivery Workflow

The businesses that handle PEPPOL smoothly are the ones that treat delivery confirmation as a standard part of their invoicing workflow — not something they check only when there is a problem.

Dokus tracks PEPPOL delivery status per invoice automatically through its integration with Recommand. Each invoice shows its transmission state, and anything that fails to deliver triggers a notification rather than a silent gap. That audit trail — visible per document — is what makes the conversations above shorter and the resolutions cleaner.

If you are currently working with invoicing software that does not give you delivery confirmation at the document level, that is worth fixing before the next invoice dispute.