Factur-X and ZUGFeRD: the PDF that carries an XML invoice

One file, two faces

Factur-X — known as ZUGFeRD in Germany — is a hybrid format. Technically it is a PDF/A-3, that is, a PDF able to carry attachments. It brings two things together in a single file:

• The printable face: the page you see on screen, with the logo, the line table and the totals. That is the one that goes in the folder.
• The structured face: an attached XML file, usually named factur-x.xml or zugferd-invoice.xml, holding the same information as data. That is the one software reads.

Both faces must say the same thing. That is the whole point of the format: one invoice, two ways of reading it. The embedded XML is written in the CII syntax, the same one used by standalone CII files.

Why the PDF displays but the data is elsewhere

When you double-click a hybrid PDF, your reader does its job: it renders the page. It has no reason to tell you a data file is attached behind it. Some readers offer an "attachments" panel or a paperclip icon; others show it nowhere at all.

So you believe you are holding an ordinary PDF while the usable part is invisible. That has one important practical consequence: if you print the file and scan it back, or save it from a tool that rewrites it, the attachment disappears. What is left is a picture of an invoice, which is no longer an electronic invoice.

Always keep the file exactly as you received it — do not re-save it through a PDF editor.

How to open a hybrid PDF and see what is inside

1. Drop the PDF on the drop zone. The embedded XML is extracted directly, without going through any PDF software.
2. The invoice is displayed from the data, not from the printed page: that is the version your accounting system will receive.
3. The declared profile appears at the top — Factur-X BASIC, Factur-X EN 16931, ZUGFeRD EXTENDED, and so on.
4. The findings follow, with the amounts concerned.

If the PDF holds no structured invoice you will know immediately: it is then a plain PDF, a printed or scanned invoice, and not an electronic invoice in the legal sense. Nothing is guessed from the image, and no text recognition is attempted.

Profiles: why two hybrid PDFs are not alike

The format comes in several profiles, from the lightest to the most complete: MINIMUM, BASIC WL, BASIC, EN 16931 — also called COMFORT — and EXTENDED. The profile is declared inside the file and shown as soon as it is read.

The difference is not theoretical. MINIMUM and BASIC WL carry no line details: they hold summary data, essentially. If you are looking for the item-by-item breakdown and it does not appear, that is not a reading failure — the information only exists in the printed part of the PDF.

It is also why the same check does not apply identically to every profile: you cannot fault a summary file for failing to detail what it was never meant to carry.

What to check on a hybrid PDF you received

• The amount due: the one in the data and the one printed on the page must agree.
• The IBAN: the most sensitive figure on any invoice. Its check digits are verified automatically.
• The VAT: for each rate, the amount stated must match the taxable base.
• The due date: it cannot fall before the issue date.
• The VAT number and company identifier of the issuer, whose structure is checked.

If what you receive is bare .xml files instead, those are UBL or CII. The format comparison shows in one table what separates them.