What Is PDF/A Format? The Complete Archiving Guide

What Is PDF/A?

PDF/A is a subset of the PDF standard specifically designed for long-term archiving of electronic documents. The "A" stands for Archive. It is defined by the international standard ISO 19005, and it ensures that a document can be rendered in exactly the same way decades or even centuries from now, regardless of what software or operating system is used to open it.

Governments, legal systems, libraries, hospitals, and financial institutions use PDF/A as the required format for permanent records — because a regular PDF might rely on external resources, fonts, or scripts that could become unavailable in the future.

Why Regular PDF Is Not Suitable for Long-Term Archiving

A standard PDF file can reference:

• External fonts — If the font is not embedded, the document depends on the viewer having the font installed
• External content — Videos, audio, or web links that point to content that may no longer exist
• Encryption — A password-protected PDF may not be openable if the password is lost
• JavaScript — Scripts that manipulate the document depend on future software support
• Colour profiles — Without embedded ICC profiles, colours may render differently on different devices

PDF/A eliminates all of these dependencies by requiring that everything needed to display the document is embedded within the file itself.

PDF/A Versions Explained

There are three main versions, each more capable than the last:

PDF/A-1 (ISO 19005-1, 2005)

The strictest and most widely supported version. Based on PDF 1.4.

• All fonts must be embedded
• No encryption allowed
• No external content references
• No JavaScript
• No audio or video
• Two sub-variants: PDF/A-1a (full accessibility, tagged structure) and PDF/A-1b (basic compliance)

Use when: Maximum compatibility and strictest compliance are required (legal, government, courts).

PDF/A-2 (ISO 19005-2, 2011)

Based on PDF 1.7. Adds support for:

• JPEG 2000 compression (smaller file sizes)
• Transparency and layers
• PDF/A files embedded within a PDF/A file
• OpenType fonts

Use when: You need better compression or transparency support while maintaining archival compliance.

PDF/A-3 (ISO 19005-3, 2012)

Same as PDF/A-2 but allows any type of file to be embedded — spreadsheets, XML data, source files.

• An invoice PDF can embed the original XML data
• A document can embed its own source files

Use when: You need to bundle source data with the visual document (e-invoicing, hybrid archiving).

PDF/A-1a vs PDF/A-1b

Within PDF/A-1, there are two conformance levels:

PDF/A-1b is the minimum requirement for most archiving use cases. PDF/A-1a is required when the document must also be accessible to screen readers (which read tagged structure).

What Gets Removed During PDF/A Conversion

When converting a regular PDF to PDF/A, the following may be removed or altered:

• Encryption and passwords — Must be removed
• Embedded JavaScript — Stripped
• Audio and video (PDF/A-1 and -2) — Removed
• External hyperlinks to resources — Preserved as links but external content not embedded
• Unembedded fonts — Converted to outlines (text becomes vector shapes) if the font cannot be embedded

This means converting to PDF/A may slightly change how the document looks (font substitution, removed interactive features).

How to Convert PDF to PDF/A

Using ToolsofPDF

1. Go to PDF to PDF/A
2. Upload your PDF
3. Select the conformance level (PDF/A-1b is recommended for most uses)
4. Click Convert
5. Download your PDF/A file

Using Adobe Acrobat Pro

1. Open your PDF
2. Go to Tools → Preflight
3. In the Preflight dialog, find PDF/A-1b (or your target standard) under "PDF/A compliance"
4. Click Analyse and fix
5. Save the converted file

Using Microsoft Word (Export Option)

When saving a Word document as PDF:

1. File → Save As → PDF
2. Click More Options
3. Under PDF Options, tick ISO 19005-1 compliant (PDF/A)
4. Click OK → Save

Verifying PDF/A Compliance

After conversion, you should verify the file actually meets the standard:

Free verification tools:

• PDF/A Pilot (online verifier at pdf-tools.com)
• veraPDF — open-source validator (verapdf.org)
• Adobe Acrobat Pro — Preflight → Check compliance

A verification report shows any remaining non-conformances.

When Is PDF/A Required?

PDF/A is typically required by:

• Government agencies — Many national archives mandate PDF/A for submitted documents
• Courts and legal systems — Court filings often require PDF/A-1b or PDF/A-2b
• Healthcare — Patient records for long-term retention
• Finance — Auditable records, e-invoices
• Libraries and universities — Digital preservation of research and theses
• ISO 9001 quality management — Document control systems

Check your jurisdiction's requirements — the specific version required (1b, 2b, 3b) varies by country and use case.

Frequently Asked Questions

Can I open PDF/A files normally? Yes. Any PDF viewer can open a PDF/A file. The standard only restricts what can be inside the file — it doesn't change how you open or read it.

Does PDF/A increase file size? Usually slightly, because fonts and colour profiles must be embedded. Using PDF/A-2 with JPEG 2000 compression can mitigate this.

Can I password-protect a PDF/A file? No. Encryption is not permitted in PDF/A because it could prevent the document from being opened in the future if the password is lost.

What if my PDF has JavaScript forms? The JavaScript will be stripped during conversion. Static form fields can be preserved, but interactive scripts will be removed.

Summary

PDF/A is the international standard for documents that must remain readable indefinitely. Use PDF/A-1b for maximum compatibility, PDF/A-2b for smaller files with transparency support, and PDF/A-3 when embedding source data alongside the visual document. If your organisation submits to courts, government portals, or long-term archives, check whether PDF/A is required — and convert with ToolsofPDF or Adobe Acrobat Pro.