What Is PDF/A?
PDF/A (PDF for Archival) is an ISO-standardized subset of the PDF format specifically designed for long-term preservation of electronic documents. First published as ISO 19005-1 in 2005, PDF/A ensures that documents remain readable and visually identical regardless of the software, operating system, or hardware used to open them — now or decades in the future.
The core principle of PDF/A is self-containment. A PDF/A file must include everything needed to render the document within the file itself. No external fonts, no linked images, no external color profiles, and no dependencies on specific software features.
Think of it this way: A regular PDF is like a web page that might link to external resources. A PDF/A is like a printed book — everything you need is right there on the page, with no external dependencies.
PDF/A Levels Explained
PDF/A has evolved through several versions, each adding new capabilities while maintaining backward compatibility:
| Level | ISO Standard | Based On | Key Features |
|---|---|---|---|
| PDF/A-1b | ISO 19005-1 | PDF 1.4 | Basic compliance: visual preservation guaranteed |
| PDF/A-1a | ISO 19005-1 | PDF 1.4 | Full compliance: adds tagged structure, Unicode mapping |
| PDF/A-2b | ISO 19005-2 | PDF 1.7 | Adds JPEG2000, transparency, layers, embedded PDF/A files |
| PDF/A-2a | ISO 19005-2 | PDF 1.7 | PDF/A-2b + tagged structure and Unicode mapping |
| PDF/A-3b | ISO 19005-3 | PDF 1.7 | PDF/A-2b + embed any file type (XML, CSV, CAD) |
| PDF/A-3a | ISO 19005-3 | PDF 1.7 | PDF/A-3b + tagged structure and Unicode mapping |
The “a” suffix (accessible) requires tagged document structure for screen readers and accessibility tools. The “b” suffix (basic) only guarantees visual appearance preservation. Most organizations use the “b” variants as they are easier to produce and sufficient for archival purposes.
What’s Required vs Prohibited
Required in PDF/A
- Embedded fonts: All fonts used in the document must be fully embedded within the file. No system font references. Our Word to PDF quality guide shows how to embed fonts when saving Word as PDF on Windows and Mac.
- ICC color profiles: Color spaces must be device-independent, defined by embedded ICC profiles.
- XMP metadata: The file must contain XMP metadata identifying it as PDF/A compliant.
- Document information: Creation date and modification date must be present.
Prohibited in PDF/A
- JavaScript: No executable code of any kind.
- Audio and video: No embedded multimedia content (in any PDF/A part).
- Encryption: No password protection or access restrictions. If an existing PDF is password-protected, our unlock PDF tool can remove the restriction before you convert it to PDF/A.
- External references: No links to external files, fonts, or content.
- Transparency: Not allowed in PDF/A-1 (allowed in PDF/A-2 and later).
- LZW compression: Prohibited due to historical patent concerns.
PDF vs PDF/A Comparison
| Feature | Regular PDF | PDF/A |
|---|---|---|
| Font embedding | Optional | Required (all fonts) |
| JavaScript | Allowed | Prohibited |
| Encryption | Allowed | Prohibited |
| External links | Allowed | Web links allowed; launch actions and external content prohibited |
| Multimedia | Allowed | Prohibited |
| File size | Smaller (fonts optional) | Larger (fonts embedded) |
| Long-term readability | Not guaranteed | Guaranteed by ISO standard |
| Self-contained | Not necessarily | Always |
When to Use PDF/A
PDF/A is required or strongly recommended in these scenarios:
- Legal documents: Court filings, contracts, and legal correspondence in many jurisdictions require PDF/A for electronic submission.
- Government records: Tax documents, regulatory filings, and official correspondence often mandate PDF/A format.
- Healthcare records: Medical records and patient documentation benefit from the guaranteed long-term readability of PDF/A.
- Financial records: Banking documents, audit reports, and financial statements are commonly archived in PDF/A for compliance.
- Academic publishing: Theses, dissertations, and research papers are increasingly submitted in PDF/A format for institutional repositories.
- Corporate archiving: Internal policies, board minutes, and historical documents are preserved in PDF/A for organizational continuity.
Recommendation: When in doubt, use PDF/A-1b. It is the most widely accepted level, compatible with virtually all PDF/A validators, and sufficient for most archival needs.
Creating PDF/A from Word
There are several ways to create a PDF/A file from a Word document:
- Microsoft Word: File → Save As → PDF → Options → tick “PDF/A compliant” (“ISO 19005-1 compliant (PDF/A)” in older versions).
- LibreOffice Writer: File → Export as PDF → tick “Archive (PDF/A, ISO 19005)” and choose PDF/A-1b, PDF/A-2b or PDF/A-3b.
- Online converters: CleverUtils converts DOCX to a regular PDF with LibreOffice, not to PDF/A. For an archival file, use Word or LibreOffice with the options above.
After creating a PDF/A file, validate it using a PDF/A validator (such as veraPDF or Adobe Acrobat Pro’s Preflight tool) to confirm compliance with the standard.
PDF/A-4 and the “u” Level
- Level u (Unicode): added in PDF/A-2 and PDF/A-3. It sits between b and a: the page must look right and all text must map to Unicode, so it can be searched and copied. Tagging for accessibility is not required. Scanned pages have no text layer, so read about OCR for scanned PDFs before aiming for level u.
- PDF/A-4 (ISO 19005-4:2020): based on PDF 2.0. It drops the a, b and u levels and has three variants: PDF/A-4, PDF/A-4f (allows embedded files of any type) and PDF/A-4e (for engineering documents with 3D content).
- Which to pick: use the version your archive or court asks for. Without a rule, PDF/A-2b or PDF/A-2u is a widely supported default.
How to Check if a PDF Is PDF/A
- Acrobat and Acrobat Reader: a PDF that claims PDF/A conformance opens with a blue bar saying the file claims compliance with the PDF/A standard.
- Metadata: the claim lives in the file’s XMP metadata as
pdfaid:part(1–4) andpdfaid:conformance(A, B or U). - Validation: a claim is not proof. Check the file with veraPDF (free, open source) or Acrobat Pro’s Preflight.