Is e-invoicing mandatory in Belgium?

Yes. Belgium mandated B2B e-invoicing from January 1, 2026, making it one of the first EU countries to require structured e-invoicing for all domestic business-to-business transactions. B2G e-invoicing has been mandatory since 2024 via the Mercurius platform. Belgium accepts Peppol BIS Billing 3.0 (UBL) as the primary format. There is a 6-month grace period for B2B enforcement.

What e-invoice formats does Belgium accept?

Belgium uses Peppol BIS Billing 3.0 (UBL 2.1) as its primary e-invoice format. For B2G submissions, the Mercurius platform accepts Peppol-compliant invoices. Belgium does not have a country-specific CIUS — it follows the Peppol BIS specification directly. This makes Belgium one of the simpler countries for e-invoice compliance if you already support Peppol.

How does Peppol work for e-invoicing in Belgium?

Belgium relies heavily on Peppol for e-invoice exchange. All B2B e-invoices must be exchanged via the Peppol network or a compatible platform. Businesses need a Peppol ID (registered via an Access Point provider) and use Peppol BIS Billing 3.0 format. The Mercurius platform serves as the government's Peppol Access Point for B2G invoicing. Belgium's full adoption of Peppol means businesses already on the Peppol network have minimal additional work for compliance.

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🇧🇪 E-Invoicing in Belgium

B2G MandatoryPeppol

Verification pending: 20 December 2025

Belgium became the first EU country to mandate Peppol as the exclusive B2B e-invoicing channel when its mandate went live on January 1, 2026. All domestic B2B transactions between Belgian VAT-registered entities must use Peppol BIS Billing 3.0 in UBL format. B2G e-invoicing has been mandatory via the Mercurius platform since November 2022.

Unlike most EU countries that allow multiple formats, Belgium's mandate requires Peppol BIS Billing 3.0 exclusively for B2B — no CII, no Factur-X, no proprietary formats. Businesses must register in the Peppol network using their KBO/BCE enterprise number as the participant identifier. The Mercurius platform serves as the government's Peppol Access Point for B2G invoices using the same format.

Invoice Navigator validates Belgian e-invoices against both the Belgian CIUS rules and the core EN 16931 standard, with full Peppol BIS Billing 3.0 compliance checking. The validation engine ensures correct KBO/BCE participant lookup and Peppol network routing.

Non-compliance results in invoice rejection via the Peppol network. Non-compliant invoices may not be accepted for VAT deduction. B2G non-compliance results in payment delays and rejection by the Mercurius platform.

TL;DR

Belgium mandates Peppol BIS Billing 3.0 for all B2B e-invoicing since January 2026 — the first EU country to require Peppol exclusively. B2G via Mercurius since 2022.

Last updated: January 2026

Quick Facts

Format

peppol_bis, ubl

Peppol

Connected

CIUS Rules

Auto-Fix

91%

Portal

Mercurius ↗

Compliance

Mandate Status

Phase

Status

Scope

B2G

Live (Nov 2022)

All federal government suppliers

B2B

Live (Jan 2026)

All Belgian VAT-registered businesses

Technical Specifications

Validation enginePeppol validation (OpenPeppol rules + Belgian CIUS)

Required CIUSPeppol BIS Billing 3.0

Government portalMercurius (B2G access point)

Routing identifierKBO/BCE enterprise number (mapped to Peppol ID)

PeppolMandatory — Peppol is the sole B2B exchange channel

Accepted formatspeppol_bis, ubl

Invoice Navigator covers 89 Peppol BIS 3.0.17 rules. Auto-remediates 91% of top rejection errors.

Practical

Common Rejection Patterns

#1BE-01Belgian B2B invoices should use Peppol BIS Billing 3.0Fix guide

#2BE-02Belgian sellers should include enterprise number (KBO/BCE)Fix guide

#3BR-BE-01Enterprise Number RecommendedFix guide

#4BR-BE-02Belgian VAT number recommendedFix guide

#5BR-BE-10Belgian enterprise number formatFix guide

Invoice Navigator auto-remediates these at pipeline speed. See how →

View all Belgium error codes

Implementation Notes

Belgium is the purest Peppol mandate in the EU — no alternative channels, no national portal fallback for B2B. This simplifies format handling but creates specific integration requirements.

Peppol-only architecture. Every B2B invoice must flow through the Peppol network. Your pipeline needs a Peppol Access Point connection (either direct certification or via a certified provider). There is no government portal for B2B submission — unlike France or Italy, Belgium has no fallback channel. If your Peppol connection is down, you cannot invoice.

Routing via KBO/BCE. Belgian businesses are identified by their KBO/BCE enterprise number, which maps to their Peppol Participant ID. Your system must resolve the recipient's Peppol ID via SMP lookup before sending. If a recipient isn't registered in the Peppol directory, the invoice cannot be delivered — and they're in violation of the mandate.

B2G via Mercurius. The Mercurius platform serves as the government's Peppol Access Point. B2G invoices follow the same Peppol BIS Billing 3.0 format but route through Mercurius. If your pipeline handles both B2B and B2G, the format is identical — only the routing endpoint differs.

Common integration failures. The top rejection cause is missing or incorrect KBO/BCE number in BT-47 (Buyer Legal Registration Identifier). Belgian Peppol validation also enforces strict VAT number format (BE + 10 digits). If you're migrating from PDF/EDI to Peppol, map your customer master data to KBO/BCE numbers before go-live.

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