8 Common PDF Accessibility Mistakes and How to Fix Them

Creating accessible PDFs is essential to ensure that everyone, including people with disabilities, can access and understand your content. However, many common mistakes can hinder PDF accessibility. In this blog post, we’ll explore the most frequent errors people make when creating PDFs and provide practical solutions to correct them. By addressing these issues, you can make your PDFs more inclusive and compliant with accessibility standards like WCAG (Web Content Accessibility Guidelines) and PDF/UA (Universal Accessibility).

1. Lack of Proper Document Structure

The Mistake

Many PDFs lack a logical structure, such as headings, lists, and tables, which makes it difficult for screen readers to navigate the content. Without proper tagging, assistive technologies cannot interpret the document’s hierarchy or convey relationships between elements.

Why It Matters

Screen reader users rely on structural elements like headings (H1, H2, etc.) to understand the document’s organization and navigate efficiently. Without these, the content becomes a flat, confusing stream of text.

How to Fix It

• Use Semantic Tags: Ensure your PDF is tagged with structural elements like <H1>, <H2>, <P>, <List>, and <Table>. Most PDF authoring tools, like Adobe Acrobat Pro, allow you to add and edit tags.
• Create a Logical Heading Hierarchy: Organize content with a clear heading structure (e.g., H1 for the main title, H2 for section titles, H3 for subsections). Avoid skipping heading levels.
• Check the Tag Tree: In Adobe Acrobat, use the Tags panel to verify that the tag tree reflects the document’s logical structure. Ensure all content is tagged appropriately.
• Use Authoring Tools Wisely: When creating PDFs from Word, Google Docs, or InDesign, apply proper styles (e.g., Heading 1, Heading 2) before exporting to PDF. This ensures tags are generated automatically.

2. Missing or Inaccurate Alt Text for Images

The Mistake

Images in PDFs often lack alternative text (alt text) or have poorly written descriptions. Alt text is a short description that conveys the purpose or content of an image for users who cannot see it.

Why It Matters

Without alt text, screen reader users miss critical information conveyed by images, charts, or diagrams. Inaccurate or overly vague alt text can also confuse users.

How to Fix It

• Add Alt Text to Images: In Adobe Acrobat, right-click an image in the Tags panel, select “Properties,” and enter a concise, descriptive alt text (e.g., “Bar chart showing sales growth from 2020 to 2023”).
• Be Descriptive but Concise: Alt text should describe the image’s purpose or key information without being overly verbose. For decorative images, mark them as “Artifact” to exclude them from the tag tree.
• Test with Screen Readers: Use tools like NVDA or VoiceOver to ensure alt text is read correctly and provides meaningful context.
• Include Text Alternatives for Complex Graphics: For charts or infographics, provide a text summary in the document or as a tagged caption to ensure accessibility.

3. Improper Use of Tables

The Mistake

Tables are often used for layout purposes rather than data presentation, or they lack proper tagging, such as row and column headers. This makes it hard for screen readers to interpret the table’s structure.

Why It Matters

Screen reader users need clear table markup to understand relationships between data points. Without tagged headers, tables become a jumble of disconnected text.

How to Fix It

• Use Tables for Data Only: Avoid using tables for visual layout (e.g., aligning text or images). Instead, use CSS or other layout tools in your source document.
• Tag Table Headers: In Adobe Acrobat, ensure tables are tagged with <Table>, <TR>, <TH> (for headers), and <TD> (for data cells). Specify whether headers apply to rows, columns, or both.
• Add Scope Attributes: For complex tables, use the “Scope” attribute to indicate whether a header applies to a row or column. This helps screen readers associate headers with data cells.
• Simplify Table Structure: Keep tables as simple as possible. Avoid nested tables or merged cells unless absolutely necessary, as these can confuse assistive technologies.

4. Inaccessible Links

The Mistake

Links in PDFs often lack descriptive text or are not tagged as interactive elements, making them inaccessible to keyboard and screen reader users.

Why It Matters

Vague link text like “Click here” doesn’t convey the link’s purpose, and untagged links may not be recognized as clickable by assistive technologies.

How to Fix It

• Use Descriptive Link Text: Ensure link text clearly describes the destination or action (e.g., “Download the 2023 Annual Report” instead of “Click here”).
• Tag Links Properly: In Adobe Acrobat, tag links with the <Link> tag and include an “OBJR” (Link Object Reference) to make them interactive.
• Ensure Keyboard Accessibility: Verify that links can be accessed and activated using the keyboard (e.g., Tab and Enter keys). Use Acrobat’s Accessibility Checker to identify untagged links.
• Test Link Functionality: Confirm that links lead to the correct destination and are not broken.

5. Poor Color Contrast and Visual Design

The Mistake

PDFs often use low-contrast text (e.g., light gray on white) or rely solely on color to convey information, which can be problematic for users with visual impairments.

Why It Matters

Low contrast makes text hard to read for users with low vision or color blindness. Relying on color alone (e.g., red text to indicate errors) excludes users who cannot perceive color differences.

How to Fix It

• Check Color Contrast: Use tools like the WebAIM Contrast Checker to ensure text meets WCAG’s minimum contrast ratio (4.5:1 for normal text, 3:1 for large text).
• Avoid Color-Only Cues: Combine color with other indicators, like text labels or patterns (e.g., use “Error: Invalid input” instead of just red text).
• Use High-Contrast Fonts: Choose clear, legible fonts with sufficient weight and size (at least 12 pt for body text). Avoid overly decorative fonts.
• Test with Grayscale: View the PDF in grayscale to ensure all information is distinguishable without color.

6. Scanned PDFs Without OCR

The Mistake

Scanned PDFs are often just images of text without optical character recognition (OCR), making them inaccessible to screen readers.

Why It Matters

Without OCR, screen readers cannot extract or read the text, leaving the content completely inaccessible to users who rely on assistive technologies.

How to Fix It

• Run OCR on Scanned PDFs: In Adobe Acrobat, use the “Scan & OCR” tool to convert scanned text into selectable, searchable text. Choose “Editable Text and Images” for best results.
• Verify OCR Accuracy: After running OCR, check for errors in text recognition, especially with poor-quality scans. Manually correct any misrecognized characters.
• Tag the Document: After OCR, add structural tags (e.g., headings, paragraphs) to ensure the document is navigable by screen readers.
• Avoid Scans When Possible: Whenever possible, create PDFs directly from digital documents to avoid the need for OCR.

7. Missing Language Specification

The Mistake

PDFs often lack a specified document language, which confuses screen readers about how to pronounce the text.

Why It Matters

Screen readers rely on language metadata to select the correct pronunciation and voice. Without it, text may be read in an incorrect or unintelligible manner.

How to Fix It

• Set the Document Language: In Adobe Acrobat, go to File > Properties > Advanced, and set the primary language (e.g., “English (US)”).
• Specify Language for Specific Sections: For multilingual PDFs, use the Tags panel to apply language attributes to specific sections or paragraphs.
• Test with Screen Readers: Verify that the screen reader uses the correct language and pronunciation for the content.

8. Not Testing for Accessibility

The Mistake

Many creators assume their PDFs are accessible without testing them with assistive technologies or accessibility tools.

Why It Matters

Untested PDFs may contain hidden accessibility issues that only become apparent when used by people with disabilities. Testing ensures compliance and usability.

How to Fix It

• Use Automated Checkers: Run Adobe Acrobat’s Accessibility Checker to identify common issues like missing tags, alt text, or contrast problems.
• Test with Screen Readers: Use screen readers like NVDA, VoiceOver, or JAWS to navigate the PDF and ensure content is read correctly.
• Conduct Manual Testing: Verify keyboard navigation, link functionality, and visual clarity using a keyboard and grayscale view.
• Involve Users with Disabilities: Whenever possible, get feedback from users with disabilities to identify real-world accessibility barriers.

Conclusion

Creating accessible PDFs requires attention to detail and a commitment to inclusivity. By avoiding these common mistakes—such as missing tags, poor alt text, inaccessible tables, and lack of testing—you can ensure your PDFs are usable by everyone. Tools like Adobe Acrobat Pro, screen readers, and contrast checkers are invaluable for identifying and fixing issues. Start by incorporating these best practices into your workflow, and you’ll be well on your way to producing PDFs that meet accessibility standards and provide a better experience for all users.

For more resources, check out the PDF/UA Foundation or the WebAIM Accessibility Guidelines to deepen your understanding of accessible document creation.