What Is a Tagged PDF?

What tags look like

The Tags panel in a remediation tool shows a nested tree. A simplified technical document might look like this:

<Document>
  <H1> Introduction to Thermodynamics </H1>
  <P> The first law states that... </P>
  <Figure alt="Diagram of heat flow" />
  <H2> Mathematical Formulation </H2>
  <Formula> dU = δQ − δW </Formula>
</Document>

The tree should match the document's meaning, not merely its visual appearance. Tag order is especially important in multi-column layouts, where extracted text can otherwise jump across columns or place a caption far from its figure.

How to check if a PDF is tagged

1. Check document properties.

   In Adobe Acrobat, open File > Properties > Description and look for “Tagged PDF: Yes.” This confirms that tags exist, not that they are correct.

2. Open the Tags panel.

   Expand the structure and confirm that it begins with a Document element, uses meaningful roles, follows a sensible heading outline, and includes all real content.

3. Run a structural check.

   Use the free PDF accessibility checker for a private browser scan, then run a full accessibility checker and screen-reader test before delivery.

How to tag a PDF

1. Tag from the source

   This is usually the cleanest route. Use heading styles and real document elements in Word or Google Docs. In LaTeX, use the current tagged-PDF workflow beginning with \DocumentMetadata{}. Export with structure tags enabled and inspect the result.

2. Auto-tag in a PDF editor

   Automatic tagging can create a useful draft for a simple, single-column document. It often misreads callouts, multi-column pages, complex lists, equations, and tables. Review every page and fix the resulting tree manually.

3. Build and repair tags manually

   Manual remediation gives the most control. Create missing elements, change incorrect roles, move tags into reading order, add alt text, associate table headers, and mark decorative or repeated page furniture as artifacts. The work is thorough but can be slow, which is why outsourced quotes are often priced per page and vary sharply with complexity.

For the full workflow, see How to Make a PDF Accessible.

Common tagging mistakes

• A flat structure. Every block is tagged as a paragraph, so users cannot navigate by heading or list.
• Incorrect reading order. Content jumps between columns, repeats headers, or reads a caption before the item it explains.
• Missing or vague figure alternatives. A Figure tag exists, but its alt text is blank, a file name, or “image.”
• Tables without headers. Every cell is tagged TD, leaving screen-reader users without row or column context. See accessible table techniques.
• Untagged content. Visible text or controls never enter the tree, while decorative borders and page numbers do.

Tagged PDF vs. PDF/UA

“Tagged” means the file contains a structure tree. PDF/UA is a fuller standard for how PDF features, tags, metadata, content, and assistive technology should work together. A tagged file can still have a broken outline, poor alt text, incorrect tables, inaccessible math, or content outside the tree.

Treat tagging as the foundation, not the finish line. The result still needs automated validation and human testing against the intended use. The broader accessible PDF guide explains the other layers.