Belgium Peppol 4 Corner Model: Requirements, How it works & Benefits

With Belgium’s e-invoicing mandate, all VAT-registered businesses must send and receive structured e-invoices starting 1^st January 2026. Belgium has adopted the Peppol 4 corner model, which connects each company to the Peppol network through their chosen certified Access Point provider. 

This model enables secure, automated invoice exchange between any businesses on the network, regardless of their software. The 4-corner model is used because it allows flexibility, ensures interoperability, and prevents vendor lock-in, making compliance easier and more efficient for companies of all sizes.

Understanding the Peppol 4 Corner Model

The Peppol 4 corner model describes how electronic documents, such as invoices, move between four main participants in the Peppol network. This model ensures each company can use its own provider, avoiding “forced” choices or closed platforms. In the Belgian context, the Peppol 4 corner model is key because it gives all businesses small and large the freedom to connect through any certified provider, guaranteeing universal access to the network.

The four corners are:

• Corner 1: The sender (usually the supplier)
• Corner 2: The sender’s Peppol Access Point (AP) provider
• Corner 3: The receiver’s Peppol Access Point (AP) provider
• Corner 4: The receiver (usually the buyer)

Invoices are sent from Corner 1 through Corner 2 and Corner 3 to Corner 4, with each Access Point responsible for secure and compliant delivery. The model’s open, interoperable structure means that businesses only need one connection to the network to reach every other participant.

How the 4 Corner Model Works?

The Peppol 4 corner model works as a networked relay, connecting senders and receivers through their chosen intermediaries (Access Points). Here’s a practical breakdown of how it operates:

1. Invoice Creation: The supplier (Corner 1) generates an e-invoice in the required Peppol BIS format using their invoicing or ERP system. This structured format contains all the necessary details, such as buyer and supplier info, VAT data, and payment instructions.
2. Sender’s Access Point: The supplier’s Access Point (Corner 2) receives the invoice. This provider validates the document against Peppol and Belgian standards, checks recipient address details, and applies required security protocols.
3. Network Transfer: The sender’s AP securely transmits the validated invoice through the Peppol network to the buyer’s AP (Corner 3). This transfer uses Peppol’s global addressing and secure messaging protocols, ensuring the invoice reaches the right recipient without manual intervention.
4. Receiver’s Access Point: The buyer’s Access Point (Corner 3) receives the invoice. It checks the document’s structure, authenticity, and sender identity, then passes the invoice on to the buyer’s system (Corner 4).
5. Invoice Reception: The buyer (Corner 4) receives the structured e-invoice directly into their accounting, ERP, or invoice processing solution. This allows automated posting, approval workflows, or integration with other financial systems.
6. Acknowledgement & Error Handling: If delivery is successful, confirmation can be sent back to the supplier. If there’s an error—such as an invalid recipient address or technical issue notifications are generated so issues can be resolved quickly.

Role of Peppol Access Point in Belgium’s E-Invoicing

A Peppol Access Point is a certified provider that serves as a gateway between your business and the Peppol network. Instead of connecting directly to every trading partner, businesses send and receive invoices through their chosen AP. 

The 4-corner model’s real significance is in its decoupling: each business is free to pick any Peppol-certified provider (AP), rather than being forced onto a single platform. 

Main Functions of a Peppol Access Point

1. Network Connectivity: APs establish secure connections between businesses and the Peppol network using standard protocols.
2. Sending and Receiving E-Invoices: APs send invoices to customers’ APs and receive invoices from suppliers, always in the Peppol BIS standard required in Belgium.
3. Validation and Compliance: APs check invoice structure, data, and Peppol ID, ensuring compliance with Belgian and Peppol rules. They alert users if errors are found.
4. Security and Delivery Assurance: APs encrypt transmissions, protect against fraud, and track document status. Senders and recipients receive delivery confirmations and error reports.
5. Addressing and Directory Management: APs register businesses in the Peppol network, assigning a Peppol ID, usually based on the Belgian VAT number. This enables direct, automated routing of invoices.
6. Error Handling and Support: APs issue clear error messages for failed deliveries and often provide support and troubleshooting.
7. Integration with Business Systems: APs offer APIs or plugins to connect with ERP, accounting, or invoicing software for automated data exchange.

About ClearTax: Certified Peppol Access Point

ClearTax is a certified Peppol-accredited service provider that helps businesses generate 100% Belgian mandate compliant e-invoices. ClearTax help businesses to connect their ERP and accounting systems directly with the Peppol network for seamless, automated e-invoice generation. 

ClearTax supports creating, sending, and receiving invoices in the correct BIS format, while ensuring full compliance from a single, cloud-based management portal. The platform automates validation, delivery, error reporting, and archiving, making Peppol e-invoicing efficient, secure, and scalable.

Steps to Set Up E-invoicing Using the 4 Corner Model

To prepare for Belgium’s 2026 e-invoicing mandate, every business must be ready to exchange invoices through the Peppol 4 corner model. Setting up e-invoicing with this framework is a one-time process . Here are the practical steps to get started:

1. Choose a Peppol-certified Access Point (AP) provider. Select an AP based on your business needs, integration options, and support services (like ClearTax). Review the Belgian government’s list of certified providers if needed.
2. Register your Peppol ID. Work with your AP to register your business on the Peppol network. Your identifier is usually based on your enterprise (VAT) number, ensuring others can find and invoice you.
3. Update or configure your invoicing software. Ensure your software can generate and send invoices in the Peppol BIS format. Many modern ERP/accounting systems support this natively; if not, your AP/ASP can help bridge the gap.
4. Configure master data. Verify that all customer and supplier records include Peppol IDs and required information for structured invoicing.
5. Test with partners. Send test invoices to selected customers or suppliers to ensure the process works end-to-end. Resolve any issues with format, address, or connectivity.
6. Train staff and adjust processes. Educate your finance team on the new sending/receiving workflows and how to monitor invoice delivery or troubleshoot issues.
7. Go live and monitor. Once tested, start exchanging e-invoices via Peppol as standard. Monitor confirmations and error reports and periodically review your processes for efficiency.

Comparing E-invoicing Models: Peppol 4 Corner vs. Others

As Belgium moves toward mandatory e-invoicing and e-reporting, it’s important for businesses to understand how different e-invoicing models work. The most common models are the Peppol 4 corner model (used for B2B and B2G invoicing), the upcoming 5 corner model (which adds the tax authority for real-time reporting), the 3 corner model (older, often platform-based), and the direct 2 corner model (custom point-to-point links).

Benefits of the 4 Corner Peppol E-invoicing Model for Businesses

The Peppol 4 corner model transforms how Belgian companies manage invoicing, making it possible to connect with any trading partner through a single, open network. Here are the major benefits

• Freedom of Choice: Select any certified provider, switch as needed, and avoid vendor lock-in
• Universal Reach: One network connection reaches all partners in Belgium and across Peppol countries
• Cost Savings: Reduce manual invoice handling, postal costs, and integration expenses
• Automation: End-to-end automation for both accounts payable and receivable
• Security: Secure, encrypted document exchange with identity validation and delivery tracking
• Reliability: Confirmations and error notifications, reducing lost invoices or disputes
• Compliance: Easy adherence to Belgian and EU e-invoicing requirements
• Scalability: Easily add new partners or increase invoice volume without extra technical work
• Level Playing Field: SMEs and large enterprises have equal access to the network

Limitations of the Four Corner Peppol Model

Despite its strengths, the 4 corner model can introduce complexity during onboarding and may depend on service providers’ reliability for smooth operation. Here are some major limitations

• Onboarding Requirement: All trading partners must be registered and connected to Peppol
• Initial Setup Costs: May require investment in new software or services
• Format Restriction: Only supports Peppol BIS format; some customization may be limited
• Dependency on Providers: Businesses rely on APs for connectivity and support
• Transition Challenges: Some partners may take time to adapt, requiring temporary workarounds

Conclusion

The Peppol 4 corner model connects every business through certified service providers, called Access Points, allowing both senders and receivers to exchange structured e-invoices efficiently and securely, regardless of which provider they use. This networked approach removes the need for direct, custom connections between partners, streamlining operations and ensuring universal reach across the Belgian and international Peppol network.

Setting up requires connecting to a Peppol Access Point and ensuring e-invoice formats meet the standard, preparing businesses for current and future digital compliance requirements.