How to Check PDF Accessibility and Fix Common Issues

An accessible PDF is one that can be read and navigated by people using assistive technology — screen readers, keyboard navigation, text-to-speech software. Accessibility isn't just a courtesy; in many contexts — government agencies, educational institutions, businesses serving the public — it's a legal requirement. Here's what accessibility means for PDFs and how to check and improve yours.

Why PDF Accessibility Matters

Approximately 2.2 billion people worldwide have some form of vision impairment. Many use screen readers — software that reads document content aloud and allows navigation by keyboard. A PDF that looks fine visually may be completely unusable for someone relying on a screen reader if the underlying structure isn't correctly set up.

Legal requirements for PDF accessibility include:

• Section 508 (US federal agencies) — requires accessible electronic documents for federal websites and systems
• ADA Title III (US businesses) — courts have increasingly applied this to digital documents
• WCAG 2.1 — the international web accessibility guidelines, widely adopted for PDF documents
• EN 301 549 (European Union) — the EU's accessibility standard for ICT products and services

What Makes a PDF Accessible?

An accessible PDF has several technical properties beyond just readable text:

• Tagged PDF — a tag tree that defines the document's logical structure (headings, paragraphs, lists, tables) so screen readers can navigate it meaningfully
• Reading order — the order in which content is read aloud must match the visual reading order, which can diverge in multi-column layouts
• Alt text for images — descriptive text alternatives for images, charts, and graphics that convey information
• Document language — the primary language specified in metadata so text-to-speech uses the correct pronunciation rules
• Meaningful heading structure — proper H1, H2, H3 hierarchy so users can navigate by section
• Accessible tables — table headers identified so screen readers can associate data cells with their column and row headers
• No security restrictions on accessibility — permissions must allow screen reader access

How to Check PDF Accessibility at PDFToolShack

1. Open the Accessibility Checker tool
2. Upload your PDF
3. Run the check — the tool analyzes the document against accessibility criteria
4. Review the report — issues are categorized by type and severity
5. Fix and re-check as needed

The Most Common Accessibility Issues

1. Missing Tags (Untagged PDF)

The most fundamental issue. An untagged PDF has no structural information — to a screen reader, it's just a flat stream of text with no indication of what's a heading, what's a paragraph, or what's a table. The fix requires adding tags, which is best done by going back to the source document (Word, InDesign, etc.) and exporting with accessibility options enabled.

2. Missing or Incorrect Alt Text

Images without alt text are announced by screen readers as "image" with no further description. Decorative images should be marked as artifacts (so they're skipped). Informative images need descriptive alt text that conveys what the image shows or what data a chart represents.

3. Wrong Reading Order

In multi-column layouts, sidebars, or complex page designs, the PDF's internal reading order may not match the visual layout. A screen reader following the wrong order produces a confused, non-sequential reading experience. This requires reordering the tag tree in the accessibility panel.

4. Missing Document Language

Without a specified language, text-to-speech software can't apply the correct pronunciation rules. This is a quick fix — set the document language in properties or metadata.

5. Scanned PDF With No Text Layer

A scanned PDF is an image — there's no text for a screen reader to read at all. The fix is to run PDF OCR to add a text layer, then check the resulting PDF's structure.

Accessible PDFs Start at the Source

The most efficient approach to PDF accessibility is to build it into the source document before export. In Microsoft Word: use the built-in heading styles (Heading 1, Heading 2), add alt text to images via right-click → Edit Alt Text, and use the built-in table tools. When you export to PDF, check the "Document structure tags for accessibility" option. This produces a tagged PDF with correct structure from the start, requiring far less remediation than fixing an inaccessible PDF after the fact.