EN 16931 is the European semantic data standard for electronic invoices. It defines the core information an e-invoice must contain, and is implemented through syntaxes like UBL 2.1 and CII (Cross Industry Invoice), which Peppol networks carry between trading partners.

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Q: What does the Belgian B2B e-invoicing mandate require from January 2026?

From 1 January 2026, VAT-registered businesses in Belgium must issue and receive structured electronic invoices for domestic B2B transactions using the Peppol 4-corner network, in an EN 16931-compliant format (UBL 2.1 or CII 16B); some hybrid formats like Factur-X/ZUGFeRD are also recognized for specific cases. E-invoices must be archived for at least 7 years.

TimeTracker sends invoices over the Peppol network and embeds Factur-X/ZUGFeRD data (EN 16931) directly in your PDFs — built with the Belgian B2B mandate in mind, running entirely on your own server.

Last updated: September 17, 2026

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The Belgian B2B mandate, in plain terms

From 1 January 2026, VAT-registered businesses in Belgium must issue and receive structured electronic invoices for domestic B2B transactions over the Peppol 4-corner network, in an EN 16931-compliant format — UBL 2.1 or CII 16B (some hybrid formats such as Factur-X/ZUGFeRD are also recognized for specific cases). E-invoices must be archived for at least seven years, and non-compliance carries graduated penalties. Real-time reporting (Peppol 5-corner) is scheduled to follow in January 2028, with intra-EU B2B e-reporting from January 2030.

This isn't unique to Belgium — it's part of a broader EU move toward mandatory structured e-invoicing (ViDA). If you invoice B2B clients in Belgium, or expect to expand there, it's worth understanding now rather than in December 2025's crunch.

Sources: Belgian federal tax administration guidance and European Commission eInvoicing country page for Belgium (re-check before relying on this for compliance decisions — we are not a tax or legal advisor).

Peppol, EN 16931, and UBL — what the terms mean

Peppol

A decentralized network and set of standards for exchanging e-documents. Businesses connect through certified "Access Points," not a single central hub.

EN 16931

The European semantic standard defining what data a compliant e-invoice must contain — fields, not file format.

UBL / CII

The actual XML syntaxes (UBL 2.1, or CII 16B) that carry EN 16931 data between systems over Peppol.

What TimeTracker's Peppol e-invoicing does today

Since v5.8.3, invoicing generated from tracked time can go out fully EN 16931-compliant, without a separate billing tool:

Send invoices over the Peppol network — UBL 2.1, BIS Billing 3.0
Included Peppol Bridge adapter + Admin setup wizard, works with any certified Access Point provider (generic HTTP transport; an experimental native SML/SMP/AS4 mode also exists for testing)
Factur-X / ZUGFeRD: embed CII XML (EN 16931 profile) directly into exported or emailed invoice PDFs — human- and machine-readable in one file
Optional PDF/A-3b normalization and veraPDF validation for archival-grade output
"Make all invoices PEPPOL compliant" toggle — adds mandatory BIS Billing 3.0 elements and a Download UBL button per invoice
Self-hosted: invoice data, client details, and your Access Point credentials stay on your own server

Source: TimeTracker's own docs/admin/configuration/PEPPOL_EINVOICING.md and PEPPOL_BRIDGE.md (verified 2026-09-17). See the full setup guide on GitHub.

Where the coverage stops today

Two things to know before you rely on this for compliance:

Sending, not receiving. This covers the outbound side — invoices you send to clients. TimeTracker doesn't include an accounts-payable inbox for receiving structured Peppol invoices from your own suppliers, which the Belgian mandate also requires businesses to handle.
You still need an Access Point. TimeTracker's Peppol Bridge is the adapter, not the network membership — you (or your accountant) need an account with a certified Access Point provider (the docs list presets including e-invoice.be and Peppyrus) to actually reach the Peppol network. XRechnung (the German CIUS) is explicitly not supported.

Full setup steps — environment variables, the Docker Compose snippet for the bridge service, and the admin wizard — are in PEPPOL_BRIDGE.md and PEPPOL_EINVOICING.md on GitHub.

FAQ

Does TimeTracker send Peppol e-invoices today?

Yes. Since v5.8.3, TimeTracker can send invoices over the Peppol network (UBL 2.1, BIS Billing 3.0) via the included Peppol Bridge adapter and an admin setup wizard, and can embed Factur-X/ZUGFeRD CII XML (EN 16931 profile) directly in exported or emailed invoice PDFs, with optional PDF/A-3b normalization and veraPDF validation.

What does the Belgian B2B e-invoicing mandate require from January 2026?

VAT-registered businesses must issue and receive structured electronic invoices for domestic B2B transactions using the Peppol 4-corner network, in an EN 16931-compliant format (UBL 2.1 or CII 16B). E-invoices must be archived for at least 7 years.

Does TimeTracker also handle receiving supplier invoices via Peppol?

No. TimeTracker's Peppol support covers the outbound side — sending compliant invoices to your clients. It doesn't include an accounts-payable inbox for incoming structured invoices from your own suppliers, so you'll still need a separate process for that half of the mandate.

What is EN 16931?

The European semantic data standard for electronic invoices — it defines the required data fields, implemented through syntaxes like UBL 2.1 and CII, which Peppol carries between trading partners.

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