An accessible PDF is one that people using assistive technology, screen readers, braille displays, magnifiers, can navigate and understand. Beyond being the right thing to do, accessibility is a legal requirement for many organisations. This guide covers the core ingredients and the PDF/UA standard that formalises them.
Why accessibility matters
A visually untagged PDF is, to a screen reader, an undifferentiated stream of characters, no way to know what's a heading, where a table's columns are, or what an image shows. Tagging supplies that structure. Many jurisdictions (through laws echoing WCAG and Section 508 in the US, or the EU Web Accessibility Directive) require public-facing documents to be accessible, and courts increasingly treat inaccessible documents as a compliance failure.
The core ingredients
- Tags: The hidden structure tree that labels paragraphs, headings, lists, and tables. This is the foundation everything else builds on.
- Reading order: The sequence in which content is announced. It must match the logical order, not the visual position, especially in multi-column layouts.
- Alt text: A short text description for every meaningful image. Decorative images should be marked as artifacts so they're skipped.
- Heading structure: Real H1/H2/H3 tags, properly nested, so users can jump between sections.
- Table markup: Header cells identified so rows and columns are announced with context.
- Document language: Set so the screen reader uses correct pronunciation.
- Meaningful link text and a descriptive document title.
What PDF/UA is
PDF/UA (ISO 14289, "Universal Accessibility") is the formal standard that spells out these requirements. A PDF/UA-compliant file guarantees the structure assistive technology relies on. It pairs naturally with WCAG, the web content accessibility guidelines, WCAG defines the user-facing goals, PDF/UA defines how a PDF meets them.
How to create and check one
- Start in the source app. Use real heading styles in Word or InDesign and add alt text there; exporting "tagged PDF" carries that structure across.
- Add or fix tags in Acrobat Pro: Tools → Accessibility → Autotag, then refine the reading order and tag tree manually.
- Run a check: Acrobat's Full Check, or the free PAC checker for PDF/UA conformance.
- Test with a screen reader (NVDA on Windows, VoiceOver on Mac) to hear the real experience.
Note that a permission-restricted file can block accessibility extraction; removing owner-password restrictions on a file you own also restores screen-reader access, see PDF permissions explained.