# PDF/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.

1. Open the original invoice in the tool that created it, for example your ERP, billing system, layout tool, or PDF export workflow.
2. 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.
3. 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.
4. Make sure fonts are embedded and the export does not use encryption, external media, or external file dependencies.
5. Upload the new PDF/A-3 source again, regenerate the ZUGFeRD or Factur-X PDF, and check that the warning is gone.
6. Validate the final file with the recipient channel or a PDF/A-3/ZUGFeRD validator before sending.
7. 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.
8. 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.

## Related resources

- [ZUGFeRD format guide](/resources/compliance/zugferd-format)
- [ZUGFeRD Profiles](/resources/zugferd/profiles)
- [ZUGFeRD validator](/zugferd-validator)