The original is the whole document
A ZUGFeRD invoice consists of two inseparable parts: the visible PDF page and the XML embedded in it. Both together are the original.
Whoever keeps only the visible page or “flattens” the PDF anew loses the embedded XML — and thus the structured, machine-evaluable part the GoBD actually mean.
What “flattening” does
A widespread error: open the ZUGFeRD file, “save as PDF” or print and scan it. The result looks like the invoice — but contains no XML anymore.
With that you have turned machine-evaluable data back into a picture. Exactly that the GoBD forbid. Out of convenience an e-invoice becomes a mere image file again.
PDF/A-3: why this format matters
ZUGFeRD deliberately uses PDF/A-3 — an archive format that allows embedding files and is designed for long-term stability. That is not a technical detail but the reason the visible and the structured can be kept together at all.
If the file is converted to another format without preserving the XML, the point of PDF/A-3 is gone. In doubt: convert nothing, leave the original as it arrived.
How to keep ZUGFeRD correctly
The rules are manageable:
- Store the original document unchanged — PDF including embedded XML.
- Do not flatten, do not re-render, do not scan.
- Store it unalterable and timestamped, not in the mailbox.
- Keep it retrievable over the whole retention period (generally eight years).
- An additional readable view is allowed — as a supplement, not a substitute.