What is PDF/A?
PDF/A is a version of PDF made for keeping documents for the long term. Courts, archives, governments and universities often ask for it. Here's what it is and which kind to choose.
Updated
PDF/A in one paragraph
PDF/A is an ISO standard (ISO 19005) for archiving. A PDF/A file must contain everything it needs to display exactly the same way in the future, on software that doesn't exist yet. That means embedded fonts, colours defined in a device-independent way, and nothing that depends on the outside world.
What PDF/A doesn't allow
- Fonts that aren't embedded in the file.
- Encryption and passwords, because a future reader might not have the password.
- JavaScript, and links to content outside the file that it needs to display.
- Audio and video.
- Colours without a defined colour space (PDF/A files declare an output intent with an ICC profile).
Versions: PDF/A-1, 2, 3 and 4
| Version | Based on | What it adds |
|---|---|---|
| PDF/A-1 (2005) | PDF 1.4 | The original. No transparency, layers or JPEG 2000. |
| PDF/A-2 (2011) | PDF 1.7 | Transparency, layers, JPEG 2000, and embedding other PDF/A files. |
| PDF/A-3 (2012) | PDF 1.7 | Like PDF/A-2, but any file can be attached, such as the XML data of an e-invoice. |
| PDF/A-4 (2020) | PDF 2.0 | Updated for PDF 2.0, with simpler conformance levels. |
Levels: a, b and u
PDF/A-1 has conformance levels a and b; PDF/A-2 and 3 add u. Level b (basic) guarantees the document looks the same in future. Level u adds that all text can be extracted as Unicode, so it can be searched and copied. Level a (accessible) adds a full tag structure for screen readers, which generally has to be built when the document is created.
PDF/A-2b is the usual choice: widely accepted, and it allows modern features such as transparency. Choose PDF/A-1b only if the recipient specifically asks for it, and PDF/A-3b when you need to attach source files.
Who asks for PDF/A
Many courts and electronic filing systems, national archives, public bodies and university repositories require or recommend it for documents they must keep. Some e-invoicing formats, such as ZUGFeRD and Factur-X, are built on PDF/A-3. If you're asked for "an archival PDF", PDF/A is what's meant.
How to make a PDF/A
PDF Workdesk's PDF to PDF/A converts an existing PDF to PDF/A-1b, 2b or 3b (2b by default), embedding fonts and adding the colour profile. It's free with a PDF Workdesk account, and files are deleted as soon as the result is sent back. To combine several documents into one archive file, the Archive workflow converts, merges and creates the PDF/A in one run.
Tools for this
Frequently asked questions
Can a PDF/A have a password?
No. Encryption isn't allowed in PDF/A, so remove any password first with Unlock PDF.
Is PDF/A bigger than a normal PDF?
Usually slightly, because every font and a colour profile are embedded.
Can I edit a PDF/A?
You can, but saving changes in most editors breaks conformance. Edit the original and convert again.