When working with PDFs to make them accessible, one of the first steps we learn is to ensure they are correctly tagged.
What are tags in a PDF?
Tags communicate the structure and reading order of the document to assistive technologies, allowing them to access and interpret content effectively. Tags in PDFs are like tags in HTML. For example, a <p> communicates "paragraph structure." An <H1> tag indicates a "Heading 1," which is typically the document's title.
So what's the difference between a tagged PDF and a well-tagged PDF? A simply tagged PDF is just the bare minimum in accessibility. A well-tagged PDF, one that follows the Well-Tagged PDF Specification, is the gold standard, unlocking true accessibility and reusability in a document.
Why Well-Tagged PDFs Matter?
- Accessibility - Screen reader compatibility, keyboard navigation, and cognitive clarity.
- Reusable - To repurpose or extract content in a structured way, such as pulling out tables, reusing text, or converting to other formats.
- Legal Risk - Section 508, ADA, and WCAG requirements.
- User Experience - Better usability for all, including mobile readers.
- Searchability & SEO - Well-tagged PDFs can be indexed more accurately.
Is there guidance on creating a well-tagged PDF?
The answer is yes. The PDF/UA Technical and PDF Reuse Working Groups, which are part of the PDF Association, created the Well-Tagged PDF Specification to provide guidance on what it means for a PDF to be well-tagged, particularly in the context of accessibility and how to create one.
This document describes how to create reusable and accessible documents using the Portable Document Format (PDF). It builds on the Tagged PDF features defined in PDF 2.0, extending their requirements for the purposes of reuse and accessibility. This document focuses primarily on the document format (syntax), not the content itself, and does not mandate or restrict processing of the document in any manner.
There is a large overlap between the requirements for reuse and accessibility. However, some requirements are critical for reuse whereas others are critical for accessibility. This document clearly identifies the requirements for each use case via a conformance level mechanism.
What Makes a PDF Well-Structured?
"The reusability and accessibility of a PDF file depends on the inclusion of a variety of semantic information such as:
- machine-readable text presented in a declared language;
- appropriate semantic structures for elements such as paragraphs, lists, tables and headings;
- the organization of semantic structures in a logical reading order;
- accurate representation of the content’s stylistic properties;
- descriptive metadata, such as alternate descriptions for images."
If you look closely at the list above, you’ll see that a truly accessible PDF and a truly accessible webpage have a lot in common.
Investing in well-tagged PDFs isn’t just about passing the accessibility audit—it’s about future-proofing your content, ensuring inclusivity, and maximizing usability for all readers, regardless of how they access your document. The Well-Tagged PDF Specification offers a clear roadmap for moving beyond "just tagged" and toward documents that are accessible by everyone.
Resources
- Well-Tagged PDF (WTPDF)
- Common PDF tags and their usage
- Questions and Answers about Tagged PDF
- PDF Association's Matterhorn Protocol (PDF)
- ISO 32000-2: Portable document format – Part 2: PDF 2.0
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