Serbia delays Sistem e-Faktura 4.0.0 by five days, then ships it

What changed in detail

The Serbian Sistem e-Faktura announced on 24 July 2026 that the production deployment of SEF version 4.0.0, previously scheduled for 26 July 2026, is postponed. The notice states that because of the significant changes and new functionality in that version, users are being given a minimum of additional time to adapt and make the necessary changes in their internal systems, and that information about the new production availability date will be published in due course.

Version 4.0.0 introduces integration with the SEF Admin module and mandatory quantity and price field validation on all electronic invoice types.

The delay was short and is over. The eFaktura version log records 4.0.0 reaching production on 31 July 2026 — five days after the original date, not an open-ended postponement — and version 4.1.0 following it into production on 2 August 2026.

What it means

The mandatory quantity/price validation is the part to plan for, not the date. It will reject invoices that the current version accepts, so any line without a populated quantity or unit price — common in service invoicing, credit notes and rounding lines — becomes a failure rather than a warning.

Read the postponement notice for what it was: five days of adaptation time, not a change of direction. 4.0.0 is live and has already been superseded by 4.1.0, so the validation rules are in force now. If you are still testing against a pre-4.0.0 environment, that is the gap to close. The wider lesson is about the source rather than Serbia — the notice announcing a delay stays up and reads as current long after the delay has been resolved somewhere else on the same site.