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How to Tag PDFs for Accessibility: Tags, Structure and Best Practices

This guide explains how to tag PDFs for accessibility, covering the tag types, structure tree, and a decision framework for fixing the source or repairing a PDF. It gives step-by-step workflows for exporting tagged PDFs and for repairing tags in Adobe Acrobat, plus testing tips, common mistakes and a pre-publish checklist.

How to Tag PDFs for Accessibility starts with understanding tags, structure and a clear repair plan. This guide shows what PDF tags do, when to fix the source file and how to repair a PDF using common tools.

Why tag a PDF?

Tags give a PDF a logical structure that assistive technologies use to read content aloud or navigate. Tagged PDFs meet accessibility standards such as PDF/UA (ISO 14289) and support meeting WCAG 2.1 success criteria at levels A and AA. Untagged PDFs are hard for screen reader users to follow, and they often fail automated checks or procurement rules such as Section 508.

What PDF tags and the structure tree are

A PDF tag is a semantic label on content. Tags form a structure tree that mirrors the document order. Important elements include:

  • Headings — H1, H2, H3 etc. Used for navigation.
  • Paragraph — P
  • List — L, LI, Lbl, LBody
  • Table — Table, TR, TH, TD
  • Figure — Figure with alternate text
  • Artifact — decorative content excluded from reading order

Also important are:

  • Role map — maps custom roles to standard ones
  • Language attribute — marks the document or paragraph language
  • Alternate text — for meaningful images and figures
  • Reading order — the sequence assistive tech follows

Decision framework: fix in the source or fix in the PDF?

Fix in the source when you can. Tagged export preserves structure. Fix in the PDF when you do not have the source or it cannot be rebuilt. Use this quick decision flow:

  • If you control the source and it uses styles: export a tagged PDF from Word, PowerPoint or InDesign.
  • If you only have the PDF: repair tags in a PDF editor such as Adobe Acrobat Pro or a specialist tool.
  • If the PDF is a scanned image: run OCR first, then tag the resulting text.

Best-practice workflow to produce tagged PDFs (preferred)

  1. Use semantic styles in the source document. Headings must use heading styles, lists must use list features, tables must be true tables.
  2. Set the document language in the source document properties.
  3. When exporting to PDF from Microsoft Word: use Save As or Export to PDF and check the option to include document structure tags for accessibility.
  4. When exporting from Adobe InDesign: choose the Tagged PDF option in the export dialog.
  5. Open the exported PDF in an accessibility checker and run a PDF/UA or WCAG check before publishing.

Practical step-by-step: tagging a PDF in Adobe Acrobat Pro (quick repair workflow)

These steps show the common repair path when you only have a PDF. Exact menu names can vary between releases but the core tools are the same.

  1. Open the PDF in Acrobat Pro.
  2. Run Autotag Document from the Accessibility tools to create a basic structure tree.
  3. Open the Tags panel to inspect the structure tree and reading order.
  4. Edit tag types: right-click a tag and change its type to H1, P, L, Table, Figure, or Artifact as required.
  5. For images, add alternate text. Use the Set Alternate Text option or right-click a Figure tag and choose properties.
  6. For tables, use the Table Editor or set header cells to TH and set scope attributes for column or row headers.
  7. Mark decorative images as Artifact so screen readers skip them.
  8. Set logical reading order using the Tags panel. Rearrange or drag tags so the tree matches the intended flow.
  9. Set the document language in Document Properties or the Accessibility settings so screen readers pronounce text correctly.
  10. Run the Accessibility Full Check. Then re-run and fix the flagged issues until there are no critical failures.

Tagging headings

Find visual headings in the Tags tree and change the tag type to the correct level (H1 to H6). Use heading levels to represent document structure, not visual size. Each page should usually start with lower-level headings, not repeated H1s.

Tagging images and figures

Add concise alternate text for meaningful images. For complex images provide a short alt attribute and a longer description in the body or an appendix. For purely decorative images mark them as Artifact.

Tagging tables

Ensure tables are tagged as Table with TR, TH and TD children. Mark header cells as TH and use scope attributes to indicate whether a header is for a row or a column. Complex layout tables that use cells for positioning may need restructuring in the source.

Lists should appear under an L tag with LI children. Links must have meaningful text, not raw URLs. For form fields add accessible names and set the tab order so keyboard users can reach each control.

Reading order and artifacts

Visual order does not always equal reading order. Check the structure tree and correct the order there. Mark non-content objects as Artifact so they are excluded from the reading sequence.

How to test and verify accessibility

Use a mix of automated checks and human testing.

  • Automated tools: Acrobat Accessibility Checker and the PDF Accessibility Checker (PAC 3) for PDF/UA conformance.
  • Screen reader testing: NVDA on Windows, VoiceOver on macOS. Listen for logical flow and correct heading navigation.
  • Keyboard testing: navigate only with Tab, Shift+Tab and arrow keys. Ensure links and form fields are reachable in order.
  • Manual checks: inspect the Tags tree for missing tags, empty tags and incorrect nesting.

Common mistakes and how to fix them

  • Missing tags. Fix: run Autotag and then clean the Tags tree manually.
  • Visual headings not tagged. Fix: change P tags to the correct H1-H6 levels.
  • Images without alt text. Fix: add concise alternate text or mark as Artifact.
  • Tables used for layout. Fix: if possible, rebuild the content in the source. Otherwise tag carefully and provide an accessible summary.
  • Incorrect reading order. Fix: reorder tags in the structure tree rather than reflowing the page.
  • Form fields without accessible names. Fix: add labels or set field names in form field properties.

Accessibility pre-publish checklist

  • Document title and language set
  • All images have alt text or are marked Artifact
  • Headings used and nested correctly
  • Tables have TH cells and proper scope
  • Lists tagged as lists
  • Links have descriptive text
  • Form fields have labels and correct tab order
  • Passed automated checks (Acrobat, PAC 3) and a sample screen reader pass

Tools and standards to know

  • Standards: PDF/UA (ISO 14289), WCAG 2.1 and Section 508 requirements in applicable jurisdictions
  • Authoring tools: Microsoft Word, Adobe InDesign
  • Repair and test tools: Adobe Acrobat Pro, PDF Accessibility Checker (PAC 3), screen readers such as NVDA and VoiceOver

Tagging PDFs is largely about semantic structure and verification. Fix things in the source when you can. When you must repair a PDF, work methodically with the Tags panel, add alt text, correct reading order and validate with PAC 3 and screen reader testing before publishing.