Here is a reasonable assumption that turns out to be wrong. You send an invoice electronically. Something about the file is off, a field in the wrong place, a format the customer's system does not quite accept. You think: fine, I will send a correction.
In Germany, that is not how it works, and the difference matters more than it sounds.
What changed
Guidance pulled together this month ahead of the January 2027 deadline restates a line that has been in the German position since the Federal Ministry of Finance letter of October 2025, and was reinforced in the ministry's e-invoicing FAQ updated in March 2026.
If a file does not match an accepted syntax or its technical specification, it is not an e-invoice. It is an ordinary invoice that happens to be in electronic form. And it does not become an e-invoice just because it successfully arrived in your customer's system. Technical arrival cures nothing.
A file in that state has to be replaced. You issue a fresh, properly formatted one.
Compare that with a technically valid e-invoice carrying wrong VAT information. Wrong amount, missing mandatory detail, incorrect VAT logic. That one you correct, the normal way.
Same-looking problem, two different remedies, and picking the wrong one leaves you without a valid invoice.
There is a second point in the same guidance. The mandatory VAT information has to sit inside the structured data itself. An attached PDF carrying the details does not satisfy the requirement, even though a human can read it perfectly. If your setup produces a readable document and treats the structured part as decoration, that is backwards.
And a third, on timing. The general transitional concession expires on 31 December 2026. From 1 January 2027, if your prior-year turnover was above 800,000 euro, you must issue structured e-invoices for qualifying domestic B2B sales. Smaller suppliers and certain EDI arrangements keep relief until 31 December 2027. Receiving has been mandatory for everyone since 1 January 2025.
What to do this week
- Check your 2026 turnover against the 800,000 euro line. That single number decides whether your deadline is January 2027 or January 2028.
- Ask your software vendor, in writing, to confirm its output validates against XRechnung or a qualifying ZUGFeRD version. Standard software will handle this, but get the confirmation rather than assuming it.
- If you or a developer built your own invoice output, or you generate invoices from a spreadsheet, run a schema validation now. This is where the problem actually lives.
- Check that required VAT details sit in the structured data, not only in the attached PDF.
Why this is worth your attention now rather than in December
If you are above 800,000 euro, January 2027 is roughly three months away, and format problems are not the kind you find by looking. You find them when a customer's system rejects an invoice, or years later when an auditor asks. Both are worse than a validation run this week.
This is general information about published guidance, not legal or tax advice. Check your own position with your tax adviser.