Peppol Invoice Validator for Belgian Companies
Belgium mandates Peppol BIS Billing 3.0 for federal suppliers (B2G) since 2020, with B2B e-invoicing rolling out from 2026 under ViDA. Validate your UBL invoices before submitting to Mercurius - free, no file uploaded.
Open Peppol ValidatorBelgian e-invoicing obligations: Mercurius & ViDA
Belgium adopted Peppol as its national e-invoicing standard for public procurement (B2G) through the Royal Decree of 9 March 2022. All federal suppliers must submit Peppol BIS Billing 3.0 invoices via the Mercurius platform (managed by BOSA - Federal Public Service for Policy and Support).
For B2B transactions, Belgium is implementing the EU ViDA (VAT in the Digital Age) directive. The Belgian transposition, developed in coordination with the FPS Finance, will mandate structured e-invoicing between VAT-registered companies from 2026, using the Peppol network as the primary exchange infrastructure.
Compliance timeline
B2G (federal): Peppol BIS Billing 3.0 mandatory for all federal public procurement. Invoices submitted via Mercurius (BOSA).
B2G extension to regional and local government entities. Flemish, Walloon, and Brussels-Capital authorities progressively adopting Peppol.
B2B (planned): mandatory e-invoicing between Belgian VAT-registered companies under ViDA transposition. Peppol network as primary channel.
Full B2B e-invoicing ecosystem: real-time VAT reporting expected alongside mandatory e-invoicing as part of the digital VAT reform.
What ValidateFin checks in your Peppol invoice
Before submitting to Mercurius or a Peppol access point, verify your invoice passes these checks:
- UBL 2.1 schema validation: the XML structure conforms to the UBL Invoice or CreditNote schema
- Peppol BIS 3.0 business rules: PEPPOL-EN16931-R* rules for amounts, VAT, and mandatory fields
- EN 16931 compliance: all mandatory fields including SellerVATIdentifier (BE VAT format)
- Belgian VAT number format: BE + 10 digits (BTW-nummer / Numéro de TVA)
- Buyer reference / purchase order reference: required by most Belgian public entities
Common errors causing Mercurius rejection
Invalid Belgian VAT number format
Belgian VAT numbers must follow the format BE0XXXXXXXXX (BE + 10 digits starting with 0 or 1). The prefix '0' or '1' after 'BE' is mandatory - older 9-digit numbers must be prefixed with 0.
Missing cbc:BuyerReference or cac:OrderReference
Most Belgian public entities require either a purchase order reference or a buyer-defined reference in the invoice. Its absence is the most common cause of Mercurius rejection.
Peppol BIS 3.0 rule PEPPOL-EN16931-R004 failure
The invoice currency (cbc:DocumentCurrencyCode) must match the currency used in all monetary amounts. Mixed currencies in a single invoice are not allowed.
Frequently asked questions
What is Mercurius and how does Peppol work in Belgium?
Mercurius is Belgium's national e-invoicing platform for public procurement, managed by BOSA. It is connected to the Peppol network, meaning any Peppol-registered service provider can deliver invoices to Belgian public entities. Invoices must follow the Peppol BIS Billing 3.0 specification (UBL 2.1 format, EN 16931 semantic model).
Can I test my Peppol invoice before sending it to a Belgian buyer?
Yes - ValidateFin validates your UBL 2.1 invoice against the Peppol BIS Billing 3.0 specification and EN 16931 rules entirely in your browser. No file is sent to any server. You get an instant report of validation errors before submitting to your Peppol access point.
Does the B2B Peppol mandate apply to all Belgian companies?
The B2B mandate planned from 2026 will apply to all VAT-registered companies in Belgium, with possible exceptions for very small businesses. The exact thresholds are being defined in the ViDA transposition legislation. ValidateFin will be updated to reflect any Belgian-specific business rules as they are published.
E-invoicing guides by country
E-invoicing rules in Belgium
Status: B2B mandatory since 1 Jan 2026. See who must issue and receive e-invoices, deadlines and accepted formats.
Validate your Peppol invoice before submitting to Mercurius
Check UBL 2.1 structure, Peppol BIS 3.0 rules, and EN 16931 compliance instantly. No file uploaded.