Section 508 requires government agencies and their contractors to make all electronic and information technology accessible. For PDFs, that means meeting the PDF/UA standard. Most government PDFs fail on the same six criteria. This guide walks through each one: what failure looks like, why it matters, and how to fix it.
Why PDF Accessibility Is Hard
PDFs were designed as final-form documents that replicate the visual appearance of print — they don't inherently carry the semantic structure that assistive technology needs. Retrofitting accessibility into legacy PDFs is time-consuming manual work. Automated tools can identify failures, but they can't fix them — remediation requires human review in Adobe Acrobat Pro.
Failure 1: No Tags (or Corrupted Tags)
A tagged PDF uses a hidden tag tree describing each element: Heading, Paragraph, List, Table, Figure. Screen readers use this to navigate. Without tags, a screen reader encounters the PDF as an undifferentiated stream — or nothing at all.
Fix: In Acrobat Pro, use Accessibility > Add Tags to Document, then manually correct tags using the Tags panel. Auto-tagging is a starting point — it reliably generates tags, but multi-column layouts, tables, and complex graphics typically need significant manual correction.
Failure 2: Scanned Image (No Text Layer)
A scanned PDF is a photograph of a document. It contains no text — just pixels. Screen readers see an image with nothing to read. This is a complete accessibility failure.
Fix: Run OCR in Acrobat Pro to add a searchable text layer. After OCR, the document still needs tagging to be fully accessible — OCR alone adds text but not semantic structure.
Failure 3: Missing Alt Text on Images
Charts, diagrams, photos, and infographics in PDFs need alternative text descriptions. Without alt text, the screen reader announces "Figure" and the user has no idea what the image contains.
Fix: In Acrobat Pro's Tags panel, locate each Figure tag, right-click > Properties, and add descriptive alt text. Write alt text that describes what the image communicates — not just what it looks like. Mark purely decorative images as Artifact.
Failure 4: Untagged or Mis-Tagged Tables
Tables need proper tag structure: Table > TR > TH/TD. Headers need scope attributes so screen readers can associate each data cell with its headers. Without this, a screen reader reads table cells as a stream of text with no structural context.
Fix: In Acrobat Pro, use the Table Editor under Accessibility tools to visually assign Header cells and set scope attributes. For complex tables with merged cells, this requires careful manual verification of every cell.
Failure 5: Logical Reading Order Not Set
Screen readers read PDFs in the tag tree order, not necessarily the visual order. Multi-column layouts, sidebars, and pull quotes frequently result in a tag order that doesn't match the intended reading order — causing a screen reader user to jump back and forth between columns in a way that's incomprehensible.
Fix: In Acrobat Pro, use the Order panel under Accessibility tools to verify and correct reading order. For complex multi-column layouts, review every page manually.
Failure 6: No Document Language Specified
PDFs should have the document language specified in their properties. Screen readers use this to select the correct voice and pronunciation rules. Without it, the screen reader may use the wrong voice or mispronounce words.
Fix: In Acrobat Pro, go to File > Properties > Advanced > Reading Options > Language. Select the correct language from the dropdown.
Prioritizing Your Remediation Queue
Most agencies have more PDFs than they can remediate at once. Prioritize: (1) PDFs that gate access to benefits or services, (2) PDFs linked from high-traffic pages, (3) PDFs published after your compliance deadline. Use our Free PDF Accessibility Checker to quickly assess which documents need remediation before you start.