Originally published at https://arling.sk/notes/e-invoice-mandatory-dates-germany-and-slovakia/

E-Invoicing Mandatory Dates in Germany and Slovakia

Two separate deadlines now govern electronic invoicing for anyone trading with Slovakia or with Germany, and the two countries reach them from opposite directions. Mandatory business to business electronic invoicing applies in Slovakia from 1 January 2027, covering domestic taxable supplies between two domestic parties who are both VAT payers. The legal basis is a change to the value added tax act itself: Act No. 385/2025 Coll. amends Act No. 222/2004 Coll. on value added tax and introduces a new Section 76a, the delivery service for electronic invoices, with effect from that same date. Germany moved earlier and more gradually. Every business there has had to be able to receive a compliant electronic invoice since 1 January 2025, while the obligation to send one is staggered by turnover and by format: companies with turnover up to 800 000 euro in the previous year keep a paper or PDF option until 31 December 2027, and the final EN 16931 deadline for every business in B2B falls on 1 January 2028. In both countries, an electronic invoice is a specific technical thing, not a PDF or a scanned paper document: it is a structured file built on the European standard EN 16931.

Slovakia: the 1 January 2027 deadline and who it covers

Slovakia's obligation is aimed squarely at domestic trade between businesses. It covers taxable supplies between two domestic parties, and both of them have to be VAT payers, from 1 January 2027. Cross border invoices and supplies involving a party that is not a domestic VAT payer sit outside this particular rule, which is why the wording matters: it is a domestic B2B obligation, not a general e-invoicing law for every transaction a company makes.

The rule was not written as a standalone regulation. Act No. 385/2025 Coll. amends the existing value added tax act, Act No. 222/2004 Coll., and inserts a new Section 76a that establishes the delivery service through which these electronic invoices move, with the same 1 January 2027 start date as the invoicing obligation itself. A company checking whether it is ready for the deadline is really checking two things at once: whether its invoicing process matches the new Section 76a delivery service, and whether the files it produces meet the format definition described below.

What actually counts as an electronic invoice

The legal definition is narrow, and it is worth stating precisely because it rules out what many businesses already do. An electronic invoice is a document issued, sent and received in a format that allows automated electronic processing, and in a data structure that follows the technical standard for electronic invoicing, meaning EN 16931 in the UBL 2.1 or CII syntax. A PDF attached to an e-mail, however neatly it is formatted, does not meet this definition, and neither does a scanned paper invoice. That single European standard, EN 16931, is what both the Slovak and the German rules build on, even though each country reached its own mandatory dates through a separate national law.

How e-invoices move in Slovakia

Slovakia settled on a decentralized delivery model rather than a central government portal. Electronic invoices travel over the Peppol network through certified delivery service providers, directly from the issuer to the recipient, with no intermediate step between the two parties; the centralized state system that was originally planned, called IS EFA, was cancelled in 2024. Selected data from every invoice is reported to the Slovak Financial Administration automatically, almost in real time, by the delivery service provider on each transmission, so the business itself files no separate report for it; the older VAT control statement and recapitulative statement are not abolished until 1 July 2030, so they keep running in parallel with the new reporting for years after the invoicing deadline. Responsibility for accrediting the delivery service providers and for the national implementation rules sits with the Slovak Peppol Authority, which is the Financial Directorate of the Slovak Republic.

Germany's staggered timeline and the two accepted formats

Germany's receiving obligation came well before its sending obligation and applies uniformly. Every business has had to be able to receive a compliant electronic invoice since 1 January 2025, and an ordinary e-mail inbox is enough to receive one; nothing special has to be installed on the receiving side. Sending is where the staggering happens, and it runs on two tracks at once: by calendar and by company size. Anyone may still issue a paper invoice or a PDF until 31 December 2026; companies whose turnover in the previous year was up to 800 000 euro keep that same option until 31 December 2027; EDI procedures that sit outside EN 16931 are allowed on that same extended timeline, until 31 December 2027; and from 1 January 2028 every business in B2B has to send electronic invoices, with no more exceptions.

Two formats meet the German definition in practice. XRechnung is the national format built on top of EN 16931, developed by KoSIT; its current release is XRechnung 3.0.2, the base version XRechnung 3.0 has applied since 1 February 2024, and it carries over the Peppol BIS Billing 3.0 business rules rather than inventing its own. ZUGFeRD takes a hybrid route instead, a PDF with a structured XML file embedded inside it, and from version 2.0.1 it satisfies German VAT law's requirements for an electronic invoice, with the exception of its MINIMUM and BASIC-WL profiles, which do not carry the full EN 16931 data model.

FAQ

Can a Slovak company still e-mail a PDF invoice to another Slovak VAT payer after 1 January 2027?

No. From that date a domestic taxable supply between two domestic VAT payers has to be issued as an electronic invoice through the new Section 76a delivery service, and a PDF sent by e-mail does not meet the legal definition of an electronic invoice, because it is not built on the EN 16931 data structure.

Does Germany's receiving obligation mean a business needs new software just to accept invoices?

Not for receiving specifically. Since 1 January 2025 a German business only has to be able to receive a compliant electronic invoice, and an ordinary e-mail inbox is sufficient for that.

Which German invoices are still allowed to skip EN 16931 altogether, and until when?

Two groups keep a longer runway than everyone else. Companies whose turnover in the previous year was up to 800 000 euro may keep sending a paper invoice or a PDF until 31 December 2027, and businesses using an EDI procedure outside EN 16931 may keep doing that on the same date; every other business loses the paper or PDF option already on 31 December 2026, and from 1 January 2028 the electronic form is mandatory for all of them.

Conclusion

Slovakia and Germany arrive at mandatory business to business electronic invoicing from different starting points and along different timelines, yet both rest on the same European data structure, EN 16931. Slovakia leaves no room for a PDF or a scanned invoice in a domestic B2B transaction, and Germany eventually leaves no room for one in a B2B transaction at all. A company trading with either country, or with both, has to track two separate sets of dates and formats rather than one: Slovakia's single 1 January 2027 start under its new Section 76a, and Germany's staggered sending obligation that only finishes running on 1 January 2028. More detail on formats and delivery is on the e-invoicing page.

ARLing also has a free e-invoicing tool.