How to Tag a PDF for Accessibility
Standards this affects
- PDF/UA — ISO 14289-1, clause 7.1 (real content tagged)
- WCAG 2.1 — 1.3.1 Info and Relationships (Level A)
- Section 508 — 502 / WCAG 2.0 AA by reference
What this means
Tags are the hidden structure tree inside a PDF that tells assistive technology what each piece of content is — a heading, a paragraph, a list, a table, a figure — and what order to read it in. An "untagged" PDF has visible text and images on the page but no underlying structure, so a screen reader has nothing reliable to announce.
Why it matters
Tagging is the single most important requirement for an accessible PDF — nearly every other accessibility feature (reading order, alt text, headings, tables) depends on the tag tree existing. Without tags, a screen reader user gets either silence or a jumbled, out-of-order stream of text. Tagging is mandatory under PDF/UA and is what most legal complaints under the ADA and Section 508 hinge on.
How the checker flags it
- The checker reports the document as "not tagged" or "untagged content".
- Acrobat's Reading Order / Tags panel is empty or shows "No Tags available".
- A screen reader reads nothing, or reads the page in the wrong order.
How to fix it
- 1
Tag the source document first, if you can
The cleanest tags come from the authoring tool, not the PDF. In Word, use real Heading styles, lists, and table headers, add alt text to images, then export with "File → Save As → PDF" (keep "Document structure tags for accessibility" checked). Re-exporting a properly structured Word/InDesign file fixes most issues at the source.
- 2
Auto-tag in Acrobat Pro
If you only have the PDF, open it in Acrobat Pro and run All Tools → Prepare for accessibility → Autotag document. This builds a first-pass tag tree automatically. Treat it as a starting point, not a finished result.
- 3
Review and correct the reading order
Auto-tagging often gets reading order and element types wrong. Use the Reading Order tool and the Tags panel to verify the sequence matches the visual order and that headings, lists, and tables are tagged with the correct element types.
- 4
Mark decorative content as artifacts
Background images, rules, page numbers, and repeating headers/footers should be tagged as artifacts so screen readers skip them. Anything that conveys meaning must stay in the tag tree.
- 5
Re-check to confirm
Run the document back through an accessibility checker. The "untagged" failure should clear, and you can then resolve any remaining issues (alt text, table headers, etc.).
Check your PDF for this issue
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Frequently asked questions
- Can I tag a PDF without Acrobat Pro?
- Yes. Automated remediation services (including this site's remediation feature) can add a tag tree, alt text, and reading order without manual work in Acrobat. For one-off documents you author yourself, re-exporting from a well-structured Word or InDesign file is the cheapest fix.
- Does "auto-tag" make my PDF compliant?
- Not by itself. Auto-tagging creates structure but frequently misorders content and mislabels elements. You still need to verify reading order, headings, alt text, and tables before a document is genuinely PDF/UA compliant.