Belgium B2G E-Invoicing: Mercurius Platform & Government Invoice Submission
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Belgium has required electronic invoicing for government contracts (B2G) since 2024 via the Mercurius platform, the federal government's central e-invoicing system. All suppliers to Belgian federal, regional, and local government entities must submit structured e-invoices through Mercurius, which connects to the PEPPOL network. With the B2B mandate now active since January 1, 2026, businesses already using Mercurius for B2G have a head start on compliance.
What Is the Mercurius Platform?
Mercurius is Belgium's centralized government e-invoicing platform, operated by the SPF BOSA (Federal Public Service Policy and Support). It serves as the gateway for all electronic invoices submitted to Belgian public sector entities.
Mercurius is Belgium's centralized government e-invoicing platform, operated by the SPF BOSA (Federal Public Service Policy and Support). It serves as the gateway for all electronic invoices submitted to Belgian public sector entities.
- Scope: Federal government, regional governments (Flanders, Wallonia, Brussels-Capital), and participating local authorities.
- Network: Connected to PEPPOL—invoices are transmitted via PEPPOL Access Points.
- Format: PEPPOL BIS Billing 3.0 (UBL 2.1)—the same format now required for B2B.
- Free portal: Small suppliers can use the Mercurius web portal to manually create and submit e-invoices at no cost.
How Do You Submit an Invoice to a Belgian Government Entity?
There are two submission methods:
There are two submission methods:
Method 1: Via PEPPOL Access Point (Recommended)
- Create your invoice in PEPPOL BIS Billing 3.0 format using your invoicing software.
- Include the government entity's PEPPOL participant ID (found in the PEPPOL directory or your contract documents).
- Your Access Point transmits the invoice to Mercurius via the PEPPOL network.
- Mercurius validates and delivers the invoice to the receiving government entity.
Method 2: Via Mercurius Web Portal (Manual)
- Access the Mercurius portal at finances.belgium.be.
- Authenticate using your Belgian eID or Itsme digital identity.
- Manually enter invoice details in the web form.
- Submit—Mercurius generates the structured e-invoice automatically.
What Are the Key Differences Between B2G and B2B E-Invoicing in Belgium?
The key advantage for businesses already using PEPPOL for B2G: the same infrastructure, format, and Access Point connection works for the B2B mandate. Invoicemonk handles both B2G and B2B e-invoicing through a single PEPPOL connection.
| Aspect | B2G (Government) | B2B (Business) |
|---|---|---|
| Mandatory since | 2024 | January 1, 2026 |
| Platform | Mercurius (PEPPOL-connected) | Any PEPPOL Access Point |
| Format | PEPPOL BIS Billing 3.0 | PEPPOL BIS Billing 3.0 |
| Free option | Mercurius web portal | Depends on Access Point |
| Recipient lookup | PEPPOL directory + contract reference | PEPPOL directory (SMP) |
The key advantage for businesses already using PEPPOL for B2G: the same infrastructure, format, and Access Point connection works for the B2B mandate. Invoicemonk handles both B2G and B2B e-invoicing through a single PEPPOL connection.
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