Peppol technical failure in Belgium: use the fallback without losing control

The fallback is an exception, not a second invoicing channel

Belgium's structured B2B e-invoicing obligation has applied since 1 January 2026. A temporary technical problem does not remove the duty to issue an invoice, but it can change how that individual invoice is delivered. The distinction matters for contractors who cannot delay a progress invoice while a customer's receiving system is unavailable.

The Belgian authorities describe a technical fallback measure: when the recipient is technically unable to receive the structured invoice, the supplier may issue the required invoice in another form. The recipient still has to take the necessary steps to restore its ability to receive structured invoices. Treat this as a bounded exception and confirm current guidance with your accountant when the facts are unclear.

Establish that the problem is on the receiving side

Do not switch to PDF because a send button showed a generic error. Capture the status from your invoicing software or access point and determine whether the document failed validation, the recipient identifier was wrong, or the recipient was technically unable to receive it.

Record:

• the customer and project;
• the invoice number and amount;
• the Peppol document or transmission reference;
• the error message and time;
• what the recipient or its provider confirmed;
• who approved use of the fallback;
• when normal structured delivery will be tried again.

An invalid VAT number, incorrect total or missing purchase-order reference is a data problem in your invoice. It is not evidence that the recipient cannot receive Peppol documents.

Keep one commercial invoice

The fallback should not create two receivables. Use the same controlled invoice record and make the delivery route visible in its history. If a PDF or paper copy is used under the exception, label the event internally and avoid generating a new invoice number merely to bypass the technical block.

Agree with the customer which document should enter its accounts payable process. If the structured version is sent later, make sure it is treated as the same invoice, not as a second demand for payment. The customer reference, project reference and amount must remain consistent.

Assign owners and a recovery deadline

The site manager should not have to decide whether a tax exception applies. Give the administrative owner responsibility for evidence and customer contact, and involve the accountant for doubtful cases. The customer should identify who is repairing its receiving route.

Set a short follow-up date. On that date, verify whether the recipient can receive structured invoices again and whether the original invoice has one agreed status. If the invoice content changed in the meantime, use the appropriate correction process rather than overwriting the original history.

Close with a reconciled audit trail

Before marking the issue resolved, confirm that the customer received the agreed document, the project has one invoice balance, the bank reconciliation expects one payment and the accounting export contains no duplicate. Keep the technical evidence with the invoice for later questions.

The fallback sits inside a wider control process. Review the Belgian Peppol step-by-step guide and the common invoicing mistakes contractors should avoid. To connect project evidence and invoicing in one workflow, explore Enfin.