A regular PDF can look different, or fail to open at all, a decade from now if it relied on a font your future computer doesn't have or a feature since deprecated. PDF/A exists to prevent that. It's the ISO standard for documents that must remain faithfully reproducible for years or decades. Here's what it is, how its versions differ, and when you'll be required to use it.
What PDF/A actually guarantees
PDF/A (ISO 19005) makes a file self-contained and device-independent. To do that it requires and forbids specific things:
- All fonts embedded, nothing depends on what's installed later.
- No external references, no linked content that could vanish.
- No encryption, an archive must be openable without a password.
- No JavaScript or executable content, behaviour must be static and predictable.
- Colour defined unambiguously via embedded colour profiles.
- Standardised metadata (XMP) so the file describes itself.
PDF/A-1, A-2 and A-3
| Version | Based on | Key additions |
|---|---|---|
| PDF/A-1 | PDF 1.4 | The strict baseline (levels A = tagged/accessible, B = visual only). |
| PDF/A-2 | PDF 1.7 | JPEG2000 compression, transparency, layers, embedding other PDF/A files. |
| PDF/A-3 | PDF 1.7 | Embed any file type (e.g. the source XML or spreadsheet) inside the archive. |
Each version also has conformance levels: level A includes accessibility tagging (see making a PDF accessible), while level B guarantees only visual reproduction.
How to convert a file to PDF/A
- Adobe Acrobat Pro: File → Save As Other → Archivable PDF (PDF/A), or use the Preflight tool to convert and verify.
- Microsoft Word: Save As PDF → Options → tick "PDF/A compliant."
- LibreOffice: File → Export as PDF → tick "Archive (PDF/A)."
Because PDF/A forbids encryption, you can't have a password-protected PDF/A file, the two goals are mutually exclusive by design.
When PDF/A is required
- Court e-filing systems in many jurisdictions.
- Government records and national archives.
- Regulatory submissions (e.g. certain financial or pharmaceutical filings).
- Libraries and institutions preserving documents for the long term.