On 15 September 2026, KoSIT published a preliminary version of XRechnung 4.0.0. It is the first XRechnung based on the revised standard EN 16931-1:2026 — and it is explicitly not intended for production use. Here is what it contains, what it means for your invoices today, and when it becomes binding.
In short: Invoices to public authorities still use XRechnung 3.0, at least until 31 July 2027. The preliminary version is meant for software vendors and public administrations to analyse. KoSIT expects the final version in spring 2027.
What was published
XRechnung is the German standard for invoices to public administration: a specification (CIUS) of the European standard, maintained by the Coordination Office for IT Standards (Koordinierungsstelle für IT-Standards, KoSIT) and published on xeinkauf.de. How XRechnung differs from ZUGFeRD is explained in XRechnung or ZUGFeRD.
The newly released “Vorversion XRechnung 4.0.0” (preliminary version) is a specification document. What is missing is what you actually use to create and check invoices: the syntax bindings to CII and UBL and the validation artefacts. These depend on preparatory work by the European standards body CEN that is still outstanding. Only once that is available can the complete package of specification, schemas and validation rules be released.
What changes in content
The changes do not come from XRechnung itself but from the revision of the underlying standard. KoSIT lists:
- more than 50 new business terms and seven new groups;
- more detailed delivery information;
- several orders and deliveries in one invoice — so far a common reason for free text or for collective invoices built with workarounds;
- dedicated fields for cash discounts (Skonto), late-payment interest and third-party claims, which today usually appear as text in the payment terms;
- attachments in XML format sent together with the invoice.
The list shows what the revision is aiming at: cases from business-to-business trade that the 2017 model — built for public procurement — could only represent through workarounds.
The timeline
| What | When |
|---|---|
| XRechnung 3.0 comes into force | 1 February 2024 |
| EN 16931-1:2026 available in English | March 2026 |
| German translation by DIN | by 30 September 2026 |
| Preliminary version XRechnung 4.0.0 | 15 September 2026 |
| Final XRechnung 4.0 with technical components | expected spring 2027 |
| XRechnung 3.0 remains in force | at least until 31 July 2027 |
| Parallel use of the old and new EN 16931-1 | planned until March 2029 |
KoSIT intends to announce the specific transition periods for XRechnung — from when authorities accept 4.0, and until when they still accept 3.0 — together with the final package. They are to fall within the framework running until March 2029. So there is no fixed mandatory date for 4.0 yet, and anyone who names one is guessing.
What this means for your invoices today
- Invoices to public authorities: continue in XRechnung 3.0. The identifier in BT-24 is
urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0. For a file based on the preliminary version 4.0, there are no official validation rules yet that it could pass. - Invoices between businesses: the preliminary version changes nothing for the mandate from 2027. ZUGFeRD 2.5.2 and Factur-X 1.09.2, which have applied since 1 September 2026, are based on the 2017 model. When ZUGFeRD adopts the revision is up to FeRD, with a release of its own.
- What is worth doing now: maintain your master data so that the new fields can be filled later. Cash discounts, late-payment interest and multiple order numbers that appear as free text on the invoice today will become fields — if you already record them separately, you won't have to pull them out of text when you switch.
- For vendors of invoicing software, the preliminary version is exactly what it is meant to be: an early look at the data model to plan the rework. The revision is not backward compatible; an existing implementation will not pick up the new terms on its own.
And in E-Rechnung Pro?
The validator checks XRechnung files in CII syntax against the rules currently in force — that is, against XRechnung 3.0 and the EN 16931:2017 model. We do not offer validation against the preliminary version 4.0: there are no official validation rules for it yet, and a “pass” against home-made rules would not be a result you could rely on. How the validation is structured and which tool it is based on is explained in How validation works and Mustang.
Frequently asked questions
Do I have to switch to XRechnung 4.0 now?
No. The preliminary version is not intended for production use, and XRechnung 3.0 remains in force at least until 31 July 2027. When 4.0 will be required will only be settled with the final package.
Will XRechnung 3.0 become invalid on 31 July 2027?
That date is a lower limit, not an end date: “at least until”. The transition periods will be set with the final version 4.0, within the parallel use of both versions of the standard until March 2029.
Does XRechnung 4.0 also affect my ZUGFeRD invoices to business customers?
Not directly. XRechnung and ZUGFeRD both implement EN 16931, but they have separate releases. The revision of the standard only reaches ZUGFeRD with a FeRD release that adopts it.
Where can I find the preliminary version?
On xeinkauf.de, the KoSIT website, under “Versionen und Bundles” (versions and bundles). You will also find all valid versions of XRechnung 3.0 there, with their bug-fix bundles.
Summary
- 15 September 2026: preliminary version XRechnung 4.0.0, the first XRechnung based on EN 16931-1:2026 — not for production.
- New: more than 50 business terms, several orders and deliveries per invoice, fields for cash discounts, late-payment interest and third-party claims, XML attachments.
- Final version expected in spring 2027; XRechnung 3.0 applies at least until 31 July 2027; parallel versions of the standard until March 2029.
- Nothing changes for the B2B mandate from 2027 — ZUGFeRD 2.x and XRechnung 3.0 apply there.
Want to know whether your current XRechnung meets the rules in force? Check your file for free — no sign-up, with the exact rule code for every error.
E-Rechnung Pro creates and validates documents against EN 16931:2017 — the version ZUGFeRD 2.x and Factur-X are built on today. We are following the EN 16931-1:2026 revision and will support it as the formats adopt it.