B2B e-invoicing in Belgium: what you need to know before 2026

From January 1, 2026 the way Belgian companies exchange invoices with each other will change permanently. The time for sending PDF invoices via email is over - they will be replaced by structured electronic invoices through the Peppol network (also read: What is Peppol). This sweeping change has significant implications for how companies organize their invoicing.

In this guide, we explain what B2B e-invoicing entails, what the legislation requires, and how to prepare your company in a timely manner for this mandatory transition.

What is an electronic B2B invoice (and how do you receive them in Peppol)

An electronic B2B invoice is much more than a PDF that you receive via email. It is a digital document with structured data that can be processed automatically by systems without human intervention.

The difference with traditional invoicing In traditional invoicing, you create an invoice in your accounting software, export it to PDF, and send it by email. The recipient must open the PDF, manually enter the data into their accounting system, and archive the invoice. This process is time-consuming and prone to errors.

In electronic invoicing, the invoice data is exchanged in a standardized XML format via the Peppol network. The recipient's system automatically reads the structured data, checks it for validity, and processes the invoice without manual intervention. This is much faster, more precise, and more efficient.

How does Peppol work technically? Peppol (Pan-European Public Procurement OnLine) is an international network for exchanging electronic documents. Each participant receives a unique Peppol Participant ID, usually based on the business number.

When you send an invoice, it does not go directly to the recipient but through so-called Access Points. These Access Points ensure validation, routing, and secure delivery. It works similarly to email, but specifically for business documents with strict validation rules.

The four types of invoicing It is important to understand the distinction between the different forms:

• B2B (Business-to-Business): Invoices between companies - mandatory via Peppol from 2026

• B2G (Business-to-Government): Invoices to governments - mandatory via Peppol since 2019

• B2C (Business-to-Consumer): Invoices to individuals - remain allowed as PDF or paper

• G2B (Government-to-Business): Invoices from governments to businesses - follow the same rules as B2B

The legislation: e-invoicing mandatory for B2B from January 1, 2026

The Belgian government has decided to make electronic invoicing mandatory as one of the first EU countries. This decision fits into the European strategy to close the VAT gap and combat fraud.

Who is subject to the obligation?

The legislation applies to all B2B transactions between Belgian companies that are VAT liable. This literally means every company, from multinationals to sole proprietors, from freelancers to non-profit organizations that conduct commercial activities.

The size of your company does not matter. Even if you only send one invoice per year to another Belgian company, it must be sent via Peppol. The only exception is medical professions under article 44 - doctors and dentists are currently exempt.

What happens to existing practices?

From January 1, 2026, PDF invoices via email will no longer meet the legal requirements for B2B transactions. This applies bi-directionally: companies must be able to send and receive electronic invoices.

Invoices to individuals (B2C) remain allowed as PDF, via email, or even on paper. Invoices from foreign suppliers also (currently) do not fall under the obligation, although Europe aims for harmonization by 2030.

Sanctions and fines for non-compliance

The Belgian government takes this obligation seriously. Substantial fines have been established: €1,500 for the first determination, €3,000 for the second determination, and €5,000 for third and subsequent determinations.

Additionally, invoices that are not sent via Peppol may be legally disputed. A customer can refuse to pay a non-compliant invoice, and you have no legal grounds to enforce payment. This makes compliance not only a legal but also a commercial necessity.

However, there is consideration for a transition period. Or at least a grace period. If you are not ready with everything by January 1, you do not immediately have to fear a fine, but potentially some protest from your customer or supplier.

How it works in practice: The role of UBL

Beneath the surface of Peppol, everything is about standardization. The core of this is UBL: Universal Business Language.

What is UBL?

UBL is an international XML standard for electronic business documents. It precisely defines which fields an invoice must contain, in what order, and in what format. This ensures that systems worldwide can read and process invoices in the same way.

A UBL invoice contains the same information as a traditional invoice - supplier, customer, products, amounts, VAT - but structured in XML tags that machines can understand.

From your invoice to UBL

As a business owner, you do not need to know how UBL works technically. You simply create an invoice in your familiar software. The software or an intermediate solution like Cashfeed automatically converts this to the correct UBL format and sends it via Peppol.

Upon receipt, the reverse happens: the UBL invoice is automatically converted to a readable format in your accounting system. The only thing you see is a neat invoice, just as you are used to.