Guide
Markdown exportPDF/A-3 for ZUGFeRD
PDF/A-3 is the archival PDF container that allows a visible invoice PDF and the machine-readable XML invoice to live in one ZUGFeRD or Factur-X file.
What makes PDF/A-3 different?
PDF/A-3 is part of the PDF/A family for long-term archiving. It requires a self-contained, reproducible PDF and, unlike PDF/A-1 or PDF/A-2, allows arbitrary embedded files. That embedded-file capability is what makes hybrid e-invoices possible.
Required for strict hybrid PDFs:
A strict ZUGFeRD or Factur-X PDF is not just any PDF with an XML attachment. It is a PDF/A-3 container with the invoice XML embedded and described with the expected metadata.
What defines a PDF/A-3 file
- Long-term archival intent under ISO 19005-3
- Self-contained rendering with embedded fonts and required color information
- Stable visual appearance without external resources
- No encryption or dynamic features that would break long-term readability
- Embedded files are allowed, including the CII XML used by ZUGFeRD and Factur-X
PDF/A-3 vs PDF/X-3
| Question | PDF/A-3 | PDF/X-3 |
|---|---|---|
| Primary purpose | Long-term archiving and reproducible viewing | Print production and prepress exchange |
| Can carry invoice XML | Yes, embedded files are allowed | Not as a compliant ZUGFeRD/Factur-X archival container |
| Strict ZUGFeRD PDF | Required | Not sufficient |
Is PDF/A-3 mandatory for ZUGFeRD?
Yes, when the output is the hybrid ZUGFeRD or Factur-X PDF. The PDF layer must be an archival PDF/A-3 container that can carry the XML payload.
- ZUGFeRD/Factur-X PDF: PDF/A-3 is required for strict compliance.
- Pure XML output such as XRechnung, UBL, or CII does not need a PDF/A-3 wrapper.
- A warning download can still be useful for review, but it should not be treated as a strictly archive-compliant hybrid invoice.
How to fix the warning
The safest fix is to create a proper PDF/A-3 source before generating the hybrid invoice. Start with the application that created the visible invoice; only convert an existing PDF if you cannot re-export the original document.
- Open the original invoice in the tool that created it, for example your ERP, billing system, layout tool, or PDF export workflow.
- Export the visible invoice as PDF/A-3b if available; PDF/A-3 is the important requirement, while PDF/A-3b is the most widely accepted conformance level for hybrid invoices.
- Do not choose print-only presets such as PDF/X-3, PDF/X-4, “press quality”, or a normal interactive PDF when the recipient requires a strict ZUGFeRD or Factur-X PDF.
- Make sure fonts are embedded and the export does not use encryption, external media, or external file dependencies.
- Upload the new PDF/A-3 source again, regenerate the ZUGFeRD or Factur-X PDF, and check that the warning is gone.
- Validate the final file with the recipient channel or a PDF/A-3/ZUGFeRD validator before sending.
- If you cannot create PDF/A-3 from the source system, convert the PDF with a dedicated PDF/A tool such as Acrobat Preflight, callas pdfToolbox, Ghostscript, or another validated workflow, then upload the converted file.
- Continue with the warning only when the recipient explicitly accepts a non-strict draft or review artifact; do not treat that download as strictly archive-compliant.