e-FFF was a Belgian UBL 2.0 invoice exchange protocol for businesses, software and accountants. Since 1 January 2026, in-scope Belgian domestic B2B invoices must be structured e-invoices. Peppol is the usual route; the official FAQ describes conditions for agreed alternatives. Klarbon does not open e-FFF files yet.
What is in an e-FFF invoice?
| Property | Value |
|---|---|
| Basis | UBL 2.0 invoice and credit note |
| Coordinated by | the Forum For the Future foundation, with software houses, businesses, accountants, service providers and public bodies as signatories |
| Belgian conventions | which fields to fill, VAT codes, rounding, discounts, file naming |
| Visual copy | the invoice as a PDF embedded in the XML |
| Transport | not defined; files went by email, upload or software exchange |
The protocol describes itself as an application protocol, not a transport protocol, open for anyone to use (e-FFF, archived). The technical manual covered the fields, tax codes, invoice lines, file naming and validation (e-FFF documentation, archived).
e-FFF, UBL.BE and Peppol BIS
| e-FFF | UBL.BE | Peppol BIS Billing 3.0 | |
|---|---|---|---|
| Syntax | UBL 2.0 | UBL 2.1 | UBL 2.1 |
| EN 16931 relationship | predates it | conformant extension, not compliant for Belgian B2B delivery (UBL.BE) | Peppol specification based on EN 16931 |
| Used for | software and accountant exchange | software and accountant exchange | the Peppol network |
Since 1 January 2026, in-scope Belgian domestic B2B invoices must be structured electronic invoices. Peppol is the usual route, but it is not the only permitted delivery arrangement; see the FPS Finance FAQ for conditions and exceptions.
What does Klarbon do with e-FFF?
Opening e-FFF files is planned, not available yet. Klarbon opens UBL 2.1 invoices, including UBL.BE and Peppol BIS; see the invoice viewer.
Related
Frequently asked questions
What is e-FFF?
A Belgian protocol for exchanging invoices between small businesses, their accounting software and their accountants, coordinated by the Forum For the Future foundation from 2012. Its invoices were UBL 2.0 XML with Belgian conventions and a PDF of the invoice embedded.
Is e-FFF still used?
Its website no longer hosts the specification, so check with your accounting software whether it still reads or writes e-FFF. Since 1 January 2026, in-scope domestic B2B invoices must be structured e-invoices. Peppol is the usual route, but the official FAQ also describes agreed alternatives.
Is an e-FFF file a valid Belgian e-invoice for 2026?
An e-FFF export to an accountant does not by itself establish that an invoice meets the Belgian domestic B2B requirements. Check the required structured format and delivery arrangement with your recipient or service provider.
Sources
- e-FFF, the protocol (archived copy of e-fff.be, in Dutch) web.archive.org
- e-FFF, documentation (archived copy of e-fff.be) web.archive.org
- FPS Finance, structured electronic invoices between companies are compulsory since 2026 einvoice.belgium.be
- FPS Finance, Belgian B2B e-invoicing FAQ efactuur.belgium.be