How to Assign Heading Level Tags (Desktop and Advanced Editor)

Overview

Heading Tags in a PDF are used to convey the structure, organization, and relationships between sections in a document. Similar to how a person with sight might use bookmarks in a PDF, a screen reader can read a list of headings.  This allows the user to quickly locate a particular section in the document that they would like to read.  For this reason, it is important that heading levels are used in a correct and logical manner. 

Prerequisites 

Assistive technologies only recognize heading levels 1-6.  It can be helpful to scan through a PDF prior to remediating it to determine which heading levels you will be using for specific content. 

Also, if you have a table of contents, you might find it helpful to print it out and write the heading levels in the margins as you remediate long documents to ensure you are assigning correct heading level tags to the content.  

Steps to Follow

1. Use Proper Heading Tags (H1–H6)

Headings must be tagged using the appropriate heading tags:

• H1 – Main document title or primary heading
• H2 – Major sections
• H3 – Subsections
• H4–H6 – Further nested levels as needed

The heading level should reflect the document's logical structure, not its visual appearance.

2. Headings Must Form a Logical Hierarchy

Heading levels should be scaffolded logically.

Correct Example

• H1 Introduction
  • H2 Purpose
  • H2 Scope
    • H3 Internal Users
    • H3 External Users

Incorrect Example

• H1 Introduction
  • H4 Purpose

Skipping levels can create confusion for assistive technology users.

Common Problems

• Using paragraph tags instead of headings
• Skipping levels without structure

Frequently Asked Questions

What are the accessibility requirements surrounding the use of heading tags in PDF documents?

WCAG Requirements

WCAG 2.2 Success Criterion 1.3.1 — Info and Relationships

Headings communicate document structure and must be programmatically determinable.

WCAG 2.2 Success Criterion 1.3.1 requires that relationships conveyed visually (such as headings and sections) also be available to assistive technologies.

WCAG 2.2 Success Criterion 2.4.6 — Headings and Labels

WCAG 2.2 Success Criterion 2.4.6 requires headings and labels to describe topic or purpose.

WCAG 2.2 Success Criterion 2.4.10 (AAA)

WCAG 2.2 Success Criterion 2.4.10 encourages the use of section headings to organize content.

PDF/UA Requirements

PDF/UA-1 (ISO 14289-1)

PDF/UA requires:

• Heading elements be tagged using H1–H6.
• Headings accurately represent document structure.
• Structural hierarchy be logical and meaningful.
• Heading tags be properly nested within the structure tree.
  
  

PDF/UA-2 (ISO 14289-2) continues these requirements and aligns them with the latest accessibility standards and PDF specifications.

Are we allowed to have more than one H1 in a PDF?

There are, essentially, two schools of thought on this but the one we go with, given the current (WCAG 2.1 and PDF/UA-1) standards is that, in the vast majority of cases (around 99%), you’re only allowed to have one H1 and it should be used for the title of the document.

If you think about what we’ve stated above, that headings are used to convey hierarchy, organization, and relationships, then, in the majority of cases, all of the sections of a document – the various chapters, for example, would be “subordinate to” the title.  So, if the title is an H1 then everything below it would be an H2 or lower. 

That said, there are rare but legitimate exceptions to the "rule," and it is possible, although unlikely, to have a document with more than one H1.  In addition, it’s worth noting that, when the PDF/UA-2 standard is published and supported by processors and assistive technologies, then this rule will change.  Then, the title of the document should be put into a Title tag and you will be allowed to have multiple H1 tags, for the headings at the beginning of each chapter, for example.  That, however, is not the case yet.  So, for now, stick with the rule of having only one H1 per document.  

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