What the Belgian mandate requires
Since 1 January 2026, every taxable person established in Belgium must issue and receive structured electronic invoices for domestic B2B transactions. A PDF attached to an email is no longer a legal invoice between Belgian businesses — the invoice must be a structured XML document (Peppol BIS Billing 3.0, which is UBL 2.1 constrained by EN 16931), and by default it travels over the Peppol network between access points, not by email at all.
The initial three-month tolerance window — available only to businesses that could show concrete progress before the deadline — has ended. Enforcement is tiered:
| Infringement | Fine |
|---|---|
| First | €1,500 |
| Second | €3,000 |
| Third and further | €5,000 |
From 2028 Belgium adds near-real-time e-reporting of invoice data to the tax authority (the Peppol “5-corner” model) — the same structured invoice, with the administration listening in. Getting the invoice format right now is the durable part of the work.
Two separate problems — network and format
Sending is solved by a Peppol access point: your accounting software, an ERP connector or a dedicated provider registers you on the network and transmits invoices. We are not an access point and do not sell one.
What we solve is the format problem. The access point transmits
whatever you hand it — but if the XML you hand it does not satisfy the EN 16931 business rules and the
Peppol (PEPPOL-EN16931-*) layer, it is rejected either by the access point's own checks or by the
receiver, usually with a bare rule ID. If your invoicing system only exports spreadsheets or PDFs, or its
“Peppol export” fails validation, that gap is yours to close — and it is exactly the gap a
CSV-to-Peppol converter and a pre-send validator exist for.
What “valid” actually means
A compliant Belgian B2B invoice must pass, at minimum:
| Layer | Examples of rules that fire |
|---|---|
| EN 16931 core business rules | BR-CO-16 (totals arithmetic), BR-CO-10 (line-sum mismatch), mandatory-field BR-* rules |
| VAT category logic | BR-S-*, BR-AE-* (reverse charge), BR-E-* (exemptions) |
| Peppol BIS 3.0 layer | PEPPOL-EN16931-*: electronic address (EAS) codes, business process ID, scheme identifiers |
Every rule ID a receiver can throw at you is documented in plain English in our error-code library.
Check an invoice against the rules — free
Drop your UBL/Peppol XML into the free validator and see every rule it breaks before your customer's access point does. No signup, no file stored.
Validate an e-invoice freeStarting from spreadsheet exports instead? The converter turns a CSV into validated Peppol BIS 3.0 invoices — up to three per upload free.
Neighbouring deadlines
Selling into France? The French receive-mandate lands on 1 September 2026. Invoicing German customers? Germany's issuance obligation starts January 2027.