A wrongly formatted file is not an e-invoice at all, and the transition ends 31 December 2026

German guidance draws a line that catches people out. If a file does not match an accepted syntax or its technical specification, it is not an e-invoice. It counts as an ordinary invoice that happens to be electronic, and it does not become valid just because it landed in your customer's system. A file like that has to be replaced, not corrected. That is different from a technically valid e-invoice that carries wrong VAT details, which you fix the normal way with a correction. The second point is where the required VAT information sits. It has to be inside the structured data. A PDF attachment carrying the details does not count, even if a human can read it. The third point is timing. The general transitional concession runs out on 31 December 2026. From 1 January 2027 businesses with prior-year turnover above 800,000 euro must issue structured e-invoices for domestic B2B sales. Smaller suppliers and certain EDI arrangements keep relief until 31 December 2027. Receiving has been mandatory since 1 January 2025. If you use standard accounting software this is your vendor's problem. It becomes your problem if you or a developer built your own invoice output, or if you export invoices from a spreadsheet.

What to do