Your client asked for an e-invoice and named a format. The names sound like competing products; they are closer to different answers to one question — how do you put invoice data in a file that software can read without a human retyping it.
The three you will actually meet
| Format | What it is | What you get |
|---|---|---|
| XRechnung | The German profile of the European standard EN 16931. Pure structured data. | An `.xml` file. There is nothing to look at without a viewer. |
| ZUGFeRD | A hybrid: an ordinary PDF with the same structured data embedded inside it. | A `.pdf` that opens normally and also carries machine-readable data. |
| Factur-X | The French name for the same hybrid approach. Aligned with ZUGFeRD. | A `.pdf`, as above. |
All three can satisfy the European standard underneath. The real difference is whether a person can open the file and see an invoice, or whether they need software to render it.
Which one to send
- **A German public authority:** an XRechnung. This is what the portals are built to accept, and it is the safe assumption.
- **A business that asked for "eine E-Rechnung":** ask which. Larger companies with their own accounts-payable systems often prefer the hybrid, because a human can still read it.
- **A business that asked for a PDF:** a PDF. Not everything is an e-invoice, and inventing a requirement helps nobody.
It is tempting to reason that a PDF-with-data satisfies both camps. It does not: a portal expecting an XML file will reject a PDF whatever is embedded in it. Send the format that was asked for.
Telling what you were sent
- A file ending `.xml` that looks like angle brackets: a structured invoice, most likely an XRechnung.
- A file ending `.pdf` that opens as a normal invoice: either an ordinary PDF or a hybrid — you cannot tell by looking.
- To read the first kind, use the free viewer. It handles both syntaxes the standard allows, CII and UBL, and says which one it found.
What about Peppol?
Peppol is not a rival format — it is a network for delivering invoices between organisations, and it carries documents built to the same European standard. If your client mentions it, they are describing how the invoice should travel rather than what it should contain. For most freelancers the answer remains a file sent by email.
Common questions
A hybrid PDF carries structured data and a human-readable page at once, so in that sense yes. But it is still a PDF, and a system that requires plain XML will not accept it.
XRechnung, in the CII syntax, from the free generator. Hybrid PDFs are not produced here.
The underlying data is the same, so nothing about your invoice changes — only the file you export. That is the practical argument for keeping invoices in something that can emit either, rather than in a word processor.
InkVoice keeps the invoice and exports the XRechnung when it is wanted, so changing format is a click rather than a rewrite — free for 5 clients and 10 invoices a month, no credit card.
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