B2B E-Invoicing in 2026: The Accounting Firm's Guide

B2B E-Invoicing in 2026: The Accounting Firm's Guide

The 30-second version

Structured electronic invoicing has been mandatory between VAT-registered businesses in Belgium since 1 January 2026, on the basis of the law of 6 February 2024 and the Royal Decree of 8 July 2025. Paper invoices and simple PDFs are no longer sufficient for B2B transactions; B2C remains excluded. The chosen format is Peppol BIS 3.0 (UBL XML), compliant with the European standard EN 16931, transmitted via the Peppol network. For an accounting firm, the stakes are twofold: being compliant yourself, and supporting your clients, all of whom turn to their accountant to know what to do. It's as much a constraint as an opportunity to package a valuable advisory service.

Is e-invoicing really mandatory in 2026?

Yes, and the obligation already took effect in Belgium on 1 January 2026. Every VAT-registered business established in Belgium must now issue and receive structured electronic invoices for its domestic B2B transactions.

The legal framework is set by the law of 6 February 2024, which inserted article 53 §2bis into the Belgian VAT Code, and clarified by the Royal Decree of 8 July 2025 for its practical implementation.

This obligation is part of the European ViDA (VAT in the Digital Age) drive, which aims to generalise real-time tax reporting across all member states.

An important point for firms: the obligation depends on neither size nor sector. It concerns large companies as well as self-employed individuals, non-profit associations (ASBL) and asset-holding companies, as soon as they hold an active VAT number. In other words: almost your entire client portfolio is affected.

What changes concretely for your clients

Until 2025, an invoice between businesses could circulate on paper or as a PDF by email. Since 2026, that's no longer compliant for B2B.

Here's what is now required:

• The invoice must be structured: a machine-readable file (such as UBL XML), not a mere visual document like a PDF.

• It must comply with the European standard EN 16931, in the Peppol BIS 3.0 format.

• It must be transmitted via the Peppol network, unless there is a bilateral agreement between the parties that complies with the European semantic and syntactic standards.

What remains permitted: B2C invoices (to consumers) can still be issued on paper or as a PDF. However, a business must be technically able to receive structured electronic invoices from its suppliers, even if it only invoices consumers.

What is Peppol, and why this network?

Peppol is a standardised international network that lets businesses using different software exchange electronic invoices without incompatibility.

For invoicing, it's the equivalent of what the banking network is for a transfer: no matter your bank and the recipient's, the transfer works.

Belgium didn't improvise this choice. As early as 2016, FPS BOSA was designated the national Peppol authority, and electronic invoicing to public bodies (B2G) was already mandatory for public procurement. The extension to B2B in 2026 is the logical continuation of this strategy.

In practice, a business doesn't connect "directly" to Peppol: it goes through an access point (a certified provider or software) that guarantees the format's interoperability and compliance.

Choosing this access point is one of the decisions your clients will ask you to help them make.

And France? A calendar to watch closely

France is rolling out its own e-invoicing reform, with a calendar distinct from Belgium's and built around accredited platforms (Peppol among them) and formats such as Factur-X.

⚠️ The French calendar has been postponed several times. This article deliberately cites no specific French date: check the framework in force directly on impots.gouv.fr before advising a client concerned. For a firm working with French businesses, the rule of caution is simple: follow the official communications and never commit to an unconfirmed deadline.

For your clients with cross-border Belgium–France flows, the stakes are twofold: being able to receive Peppol invoices from Belgian partners, and anticipating their own forthcoming French obligations.

Why it's an opportunity, not just a constraint

This is the point many firms miss. A complex regulatory obligation that affects all your clients at the same time is a rare moment: the one where each of them spontaneously turns to their accountant.

Three ways to make it a source of value rather than a burden :

1. The compliance-audit engagement. Each client must check that its system can issue and receive in the right format. It's a short engagement, with a high perceived value, that you can offer proactively rather than waiting for the questions.

2. Positioning yourself as the reference. The firm that clearly explains the transition — through an article, a note to its clients, a webinar — positions itself as the trusted contact on the subject. It's exactly the kind of content that attracts new clients looking for answers.

3. Modernising your own processes. Handling structured incoming invoices reduces re-keying and errors. Well equipped, a firm saves significant time on routine accounting work.

📖 Going further: Peppol explained for accounting firms [Soon] — how the network works technically, format by format, to support your clients step by step.

The compliant firm's checklist

To be compliant yourself and ready to support others:

•  Check that your accounting software issues and receives in the Peppol BIS 3.0 format compliant with EN 16931

•  Have a Peppol access point (via your software or a certified provider)

•  Be able to receive structured invoices from your own suppliers

•  Identify the clients concerned (VAT-registered with B2B flows) — i.e. almost all of them

•  Prepare a client information note explaining the obligation

•  Identify at-risk clients (still on paper/PDF) and prioritise them

•  Define your advisory offer (audit + compliance implementation)

Where CryviTis stands on this subject

CryviTis includes multi-jurisdiction invoicing designed for finance professionals. Today, B2C invoicing is operational across the four jurisdictions covered (France, Belgium, Switzerland, the UAE), with automatic application of VAT according to the client's country and currency.

Structured B2B e-invoicing (Peppol, Factur-X) is under development, precisely to meet the obligations described in this article. The founding firms — the first 50 to register — vote each month on development priorities: e-invoicing compliance is naturally one of them.

We prefer to be transparent on this point rather than prematurely announce full compliance. On a subject as sensitive as VAT, better a firm that knows exactly what works today.

FAQ — E-invoicing 2026

Is e-invoicing mandatory in 2026?

Yes in Belgium, since 1 January 2026, for B2B transactions between VAT-registered businesses (law of 6 February 2024, Royal Decree of 8 July 2025). B2C remains excluded.

In France, a distinct calendar applies, to be checked against official sources as it has been postponed several times.

Is a PDF a compliant electronic invoice?

No. A PDF, even sent by email, is not a structured electronic invoice. 2026 compliance requires a machine-readable file (UBL XML, Peppol BIS 3.0 format). The PDF is only tolerated for B2C.

What is Peppol?

A standardised international network for exchanging structured invoices between different software systems. In Belgium, it's the standard channel for B2B.

You access it through a certified access point, not directly.

What is the accountant's role?

Auditing each client's compliance, recommending a compatible solution, adapting processes and securing the receipt of structured invoices. 

It's also a packageable advisory service, at the precise moment when all clients are looking for answers.

Going further

📖 Peppol explained for accounting firms [Soon]

📖 Finding clients as an independent accountant

📖 Starting a Business in 2026: an FR/BE/CH/UAE guide — useful for your clients who are starting out and must be compliant from their very first invoice

Stay compliant, support your clients on CryviTis

➡️ Are you an accountant or tax advisor? Create your profile on CryviTis — the 50 founding firms vote each month on development priorities, including e-invoicing compliance. Free registration, no exclusivity.

CryviTis is a technical infrastructure intermediary within the meaning of EU Regulation 2022/2065. This article is informational and does not constitute personalised tax or accounting advice. Check the applicable obligations against official sources (FPS Finance in Belgium, impots.gouv.fr in France) and with your professional institute.