Peppol e-invoicing for Belgian law firms: the 2026 mandate, explained
From 1 January 2026, invoices between Belgian VAT-registered businesses must be exchanged as structured electronic documents over the Peppol network. Here is what that actually changes for a law firm — and how to comply without adding yet another portal to your month-end.
What the law requires
Belgium's B2B e-invoicing mandate (Law of 6 February 2024) makes structured electronic invoicing the rule for domestic transactions between VAT-registered businesses. "Structured" is the operative word: the legal invoice is a machine-readable document — Peppol BIS 3.0, a UBL format compliant with the European standard EN 16931 — delivered over the Peppol network. A PDF attached to an e-mail is no longer, on its own, a compliant B2B invoice.
- Who: every Belgian VAT-registered business issuing invoices to another Belgian VAT-registered business — law firms included.
- What: issue and receive structured invoices. Your firm must be reachable on the Peppol network for incoming supplier invoices too.
- What's excluded: invoices to private individuals (B2C) and to clients established outside Belgium follow their own rules — but most firms will want one system that handles all of it.
Why law firms are particularly exposed
Legal billing has quirks that generic e-invoicing plug-ins handle poorly:
- Recovered disbursements — court fees, bailiff costs, translations — must appear as distinct invoice lines with the correct VAT treatment, and that structure must survive in the UBL, not just on the PDF.
- Mixed VAT situations — standard-rated fees next to disbursements passed through at cost — require a correct per-line VAT breakdown in the structured document.
- Retainers and recurring billing — monthly drafts must generate compliant structured invoices automatically, not depend on someone re-keying them into a portal.
- Credit notes — a corrected timesheet after billing must flow into a structured credit note that references the original invoice.
How Justiora complies natively
In Justiora, the invoice is the structured document. When you issue an invoice from WIP:
- The system generates the Peppol BIS 3.0 UBL and the human-readable PDF from the same data — lines, disbursements, VAT breakdown, structured payment reference.
- It transmits the UBL over the Peppol network through your access point, and records the delivery status against the invoice.
- The same action posts the journal entry to the general ledger — revenue, recovered disbursements, VAT payable — so the accounting is complete the moment the invoice exists.
1200 Accounts receivable Dr 2,873.75
4020 Fee income — corporate Cr 2,255.00
4200 Recovered disbursements Cr 120.00
2300 VAT payable Cr 498.75
Incoming supplier invoices arrive the same way: received over Peppol, matched to a purchase entry, ready for approval — no scanning, no manual entry. And when the client pays online through the link on the invoice (Bancontact, card, iDEAL), the payment reconciles itself to the ledger.
A readiness checklist for your firm
| Question | Why it matters |
|---|---|
| Can your billing tool generate Peppol BIS 3.0 natively? | Conversion portals add a manual step to every single invoice. |
| Is your firm registered to receive on the Peppol network? | The mandate covers inbound supplier invoices too. |
| Do disbursements and VAT survive in the structured lines? | A pretty PDF with a wrong UBL is a non-compliant invoice. |
| Do credit notes reference the original invoice in the UBL? | Required for corrections after posting. |
| Does issuing the invoice also post the accounting? | Otherwise 2026 adds a document flow on top of your existing re-keying ritual. |
Frequently asked questions
When does Belgium's e-invoicing mandate start?
From 1 January 2026, structured electronic invoicing becomes mandatory for B2B transactions between Belgian VAT-registered businesses. Invoices must be exchanged as structured documents (Peppol BIS 3.0 / EN 16931), not as PDFs sent by e-mail.
Does the mandate apply to law firms?
Yes. Law firms are VAT-registered businesses; invoices they issue to Belgian business clients fall under the B2B mandate. Invoices to private individuals (B2C) are not covered by the structured-format requirement.
Is a PDF invoice sent by e-mail still compliant in 2026?
No — for B2B invoices between Belgian VAT-registered businesses, a PDF alone no longer counts as a compliant invoice. The structured UBL exchanged over Peppol is the legal invoice; the PDF becomes a human-readable copy.
What is Peppol BIS 3.0?
The standard invoice format on the Peppol network, based on UBL and compliant with EN 16931. It carries the invoice as structured data — parties, lines, VAT breakdown, payment terms — so the recipient's software processes it automatically.
How does Justiora handle the mandate?
Every invoice is generated as a Peppol BIS 3.0 UBL alongside the PDF and transmitted over the Peppol network through your access point. No separate portal, no re-keying — and the journal entry posts to the general ledger at the same moment.
Be ready before your clients ask.
A 30-minute demo: watch an invoice become a compliant Peppol document and a balanced journal entry in one action.
Book a demo — finance@justiora.com