Belgian E-Invoice Format 2026: Key Requirements for Businesses

Beginning 1 January 2026, every Belgian VAT-registered enterprise must issue and receive structured electronic invoices in the prescribed Belgian invoice format: machine-readable XML document format aligning with the European standard EN 16931 and travel exclusively through the Peppol network. This mandate means that sending a simple PDF invoice via email will no longer be valid.

Belgium has opted for Peppol BIS Billing 3.0 as its default syntax for e-invoice format. This is essentially a structured UBL-XML file that embeds all mandatory EN 16931 elements plus a handful of Belgium-specific extensions (like BE VAT codes). 

E-Invoice Formats in Belgium

Belgium has chosen a standardized approach to e-invoicing to ensure everyone uses the same language. The accepted formats are:

• Peppol BIS Billing 3.0 (UBL XML): This is the official, required e-invoice format. It's an XML file structured using UBL (Universal Business Language) and the Peppol Business Interoperability Specification (BIS). Most companies will need to use this.
• Hybrid Formats (Factur-X / PADESC): In certain cases, hybrid formats that combine a human-readable PDF with embedded XML data (like Factur-X or PADESC) may also be accepted. However, these must still meet the EN 16931 standard and be delivered through the Peppol network.

Why the E-Invoicing Format Matters

The decision to mandate the structured e-invoice format in Belgium is based on the following key factors:

• Legal Requirement: As of February 2024, Belgian VAT law makes the Peppol e-invoicing format mandatory for all established businesses. 
• Automated Tax Compliance: Structured e-invoice XML format makes it easier for tax authorities to check and process data. Belgium is preparing for real-time e-reporting, where invoice data will be sent to the tax office automatically. 
• Interoperability: After 2026, suppliers and customers will only use the Peppol BIS UBL format. This means any invoice you send or receive can be processed automatically by accounting systems. 
• Complete and Accurate Data: The EN 16931 and Peppol BIS Billing 3.0 standards ensure every required field is present—like VAT IDs, item lines, tax details, and payment info. 
• Easier Audits and Archiving: The structured format ensures data integrity and easier tracking. Auditors can quickly check standardized e-invoices, making compliance and record-keeping straightforward.

Structured vs. Unstructured  Invoice Format

Unstructured VAT invoices in Belgium such as PDFs or paper documents are only readable by humans. They require manual entry into accounting software, which is slow and often leads to errors. These formats cannot be processed automatically by digital systems.

Structured Belgian e-invoice format uses XML files designed according to official standards like Peppol BIS Billing 3.0 and EN 16931. This format is not made for direct human reading, but for automated handling by accounting and ERP systems. Every detail—buyer, seller, VAT number, line items, and payment info—is organized in a way that software can read, validate, and post automatically, with no manual retyping.

What Is EN 16931 and Belgian National Extensions

EN 16931 is the official European standard that defines what information every electronic invoice (e-invoice) must contain. Think of it as a rulebook for digital invoices across the EU—including Belgium. Its main goal is to ensure that all essential business and tax information is present and structured the same way, so e-invoices can be automatically read and processed by software, no matter which country or system you use.

Belgium has based its 2026 e-invoice mandate on EN 16931. This means all structured e-invoices must include the exact fields and structure set out by this standard. The required e invoice format for Belgium is Peppol BIS Billing 3.0 (UBL XML), which is fully compliant with EN 16931.

Belgian National Extensions

While the EN 16931 standard sets the base requirements for e-invoicing across the EU, Belgium has added its own extra rules (called “national extensions”) to reflect local tax law and business practice. For example, Belgium might require extra reference fields, specific structured communication references, or unique handling of local tax exemptions.

The Belgian implementation (Peppol BIS 3.0) requires all the following fields, plus some Belgian-specific data, like structured communication references and certain VAT codes. 

Main required fields:

• Seller and buyer VAT identification numbers
• Invoice number and date
• Detailed line items (description, quantity, unit price)
• Tax breakdown (amount, VAT rate, total VAT per line)
• Payment details (due date, payment reference, IBAN, etc.)
• Legal references and codes (e.g., Belgian VAT codes, reason for exemption if applicable)

Validation Rules for e-Invoicing

Validation rules are the “checkpoints” that every e-invoice must pass before it is considered legally valid in Belgium. These rules are not just about correct formatting—they ensure every required field is present, the information is accurate, and the invoice follows both European and Belgian-specific requirements.

BOSA (the Belgian Federal Public Service for Policy and Support) publishes a set of national extensions and validation rules. These go beyond the basic EN 16931 standard to reflect Belgian VAT codes, identifier schemes, and fiscal requirements.

Fields for Validation

• Mandatory fields: Each invoice must include specific data like VAT numbers, invoice dates, amounts, VAT rates, payment details, and more.
• Belgian VAT codes: The invoice must use Belgian VAT codes and structures, such as the “VAT BE0…” identifier for Belgian companies.
• Data accuracy: Validation checks for errors like missing buyer or seller information, incorrect VAT rates, or mismatched totals.
• Business rules: Certain logic is checked, such as if the VAT code matches the product type, or if the seller’s and buyer’s VAT numbers are correct and active.

How E-Invoices Are Sent: Peppol Network Only

Belgium requires all domestic B2B e-invoices to be exchanged through the Peppol network—a secure, standardized network used across Europe for business document exchange.

What is the Peppol Network?

Peppol (Pan-European Public Procurement Online) is a network (digital highway) that allows businesses to send and receive e-invoices in a standard, secure way, regardless of the software each party uses. Every business joins the network by connecting to a Peppol Access Point—a certified service provider who acts as your “on-ramp” to the network.

Why Peppol ?

• Interoperability: All invoices use the same standard, so any business can send to or receive from any other, regardless of their software.
• Security: Peppol ensures that invoices come from verified sources and reach the right recipient.

Sending and Recieveing E-Invoices in Your Software (ERP)

For e-invoicing to work smoothly, your accounting or ERP software needs to handle both the sending (outbound) and receiving (inbound) of e-invoices in the Peppol format.

Outbound E-Invoices (Sales Invoices)

1. You create a sales invoice as usual in your accounting system.
2. The software generates a Peppol BIS 3.0 UBL XML file for the invoice.
3. The system (or your provider) validates the invoice and sends it through your Access Point on Peppol.
4. Your customer receives the invoice directly into their system—no manual entry required.

Inbound E-Invoices (Purchase Invoices)

1. Your suppliers send you invoices in the same Peppol format, via the network.
2. Your Access Point receives the e-invoice and passes it into your accounting software.
3. The software reads all invoice details automatically—no more keying in amounts, dates, or VAT info.
4. You check and approve the invoice in your system, then process payment as usual.

Belgium E-Invoicing Format Implementation Checklist

Preparing for Belgium’s 2026 e-invoicing mandate requires a step-by-step approach. Use this checklist to make sure your business is ready to issue and receive compliant e-invoices on time.

1. Understand your legal obligations and the January 2026 deadline.
2. Assess your current invoicing process and identify system gaps.
3. Select or upgrade invoicing software that supports Peppol BIS 3.0 (UBL XML).
4. Register with an accredited Peppol Access Point.
5. Map and configure all required invoice data fields, including VAT codes.
6. Enable validation checks for EN 16931 and Belgian-specific requirements.
7. Integrate e-invoicing with your accounting or ERP workflows.
8. Run end-to-end tests with both suppliers and customers.
9. Train your finance and operations teams on the new process.
10. Communicate the change to trading partners and monitor your first e-invoice batches.

How ClearTax Can Help Early Adopters

ClearTax is built for Belgian businesses ready to lead the shift to digital compliance. As an early adopter, you benefit from a future-proof platform that makes the transition easy and seamless.

• 100% Compliance, Guaranteed: Every invoice processed through ClearTax meets all Belgian and European e-invoicing regulations, including Peppol BIS Billing 3.0, UBL/XML, and BOSA validation. 
• Integrates with Any ERP or Accounting Software: ClearTax connects easily with your existing systems—SAP, Oracle, Microsoft Dynamics, Odoo, Sage, WinBooks, or any other ERP/accounting software. Our flexible APIs and connectors ensure smooth integration without disrupting your current workflow.
• Peppol Access Point (ASP) Certified: ClearTax is an accredited Peppol Access Point, allowing you to send and receive e-invoices directly over the Peppol network, as required by Belgian law. 
• Cloud-Based E-Invoicing Management Portal: Generate, access, track, validate, and archive invoices from anywhere. Our intuitive cloud portal provides real-time status updates, full audit trails, and secure storage for your financial records.
• Maximum Automation: Automate the entire e-invoicing process—from data capture and validation to delivery and reconciliation. Save time, reduce manual effort, eliminate data entry errors.

Conclusion

Adopting the mandated e-invoice format in Belgium is now essential for all VAT-registered businesses handling domestic B2B transactions. All Belgian companies, therefore, need to 

• Generate Peppol BIS-compliant XML
• Validate it against BOSA’s national ruleset (Done by Accredited Service provider)
• Send/receive through an accredited Peppol Access Point. 

Businesses that do not switch to the structured e-invoicing format risk administrative fines and may lose the right to deduct VAT on non-compliant invoices. Beyond compliance, moving to this system brings benefits like faster payment cycles, streamlined AP/AR processing, and improved audit trails.

To prepare, businesses should map their ERP fields, integrate with ASP,  test Peppol connections during 2025, and train staff ahead of the January 2026 deadline.