A Factur-X invoice is a PDF with structured XML embedded inside it, so one file serves both the person reading it and the software processing it. ZUGFeRD is the same specification under a German name.
From 1 September 2026 every business in France must be able to receive one, with no size threshold and no transition period. Large and intermediate companies must issue from the same date, small and medium businesses from 1 September 2027. Germany crossed its reception line on 1 January 2025 and phases issuing in 2027 and 2028.
Drop a file in and see whether the XML validates, which profile it declares and how the attachment is put together. The EN 16931 rules run in your browser, so the invoice is never uploaded. The ISO PDF/A-3, XRechnung and PEPPOL BIS checks need a server and are a separate opt in that says so.
All 223 EN 16931 rules in plain language, grouped by what actually went wrong. The standard states each rule precisely and never says what to change, which is the part you need at four in the afternoon.
24 definitions for the vocabulary you meet on the way: ZUGFeRD against Factur-X, what a CIUS actually changes, why the container has to be PDF/A-3, and what each VAT category code obliges you to state.
Open the glossaryReception is the obligation with no transition period, and it is the one most people are not planning for.
What a Factur-X file is made of, the three things that have to be true at once, and the half no validator checks.
How to read a rule identifier, then the errors people actually hit, with the cause and the fix for each.
Send a typed invoice and get back a PDF/A-3 with EN 16931 CII XML embedded. Totals are derived from the lines rather than accepted from the request, and the finished XML is validated against the same CEN Schematron the free checker uses before a PDF is assembled. A failing invoice returns the findings instead of a file.
