Most PDFs are not automatically accessible. If a document lacks proper structure, tagging, reading order, or alternative text, assistive technologies such as screen readers cannot interpret it correctly.
To comply with Section 508 of the Rehabilitation Act of 1973, federal agencies and organizations receiving federal funding must ensure their electronic documents are accessible to people with disabilities. For PDFs, this means meeting technical accessibility standards aligned with WCAG and PDF/UA requirements.
Here’s how to create a truly Section 508-compliant PDF.
1. Start with an Accessible Source Document
Accessibility begins before the PDF is created.
If you’re using Microsoft Word, structure your document properly using built-in heading styles (H1, H2, H3), formatted lists, and correctly structured tables. Avoid manually bolding text to simulate headings. Screen readers rely on semantic structure, not visual styling.
Set the document language and ensure sufficient color contrast between text and background. Avoid using color alone to convey meaning.
When exported properly, much of this structure carries into the PDF.
2. Ensure Proper Tagging in the PDF
A compliant PDF must include a logical tag structure. Tags define headings, paragraphs, lists, tables, and other elements so assistive technologies can interpret content hierarchy. In Adobe Acrobat Pro: Open the Tags panel to verify structure. Confirm headings follow a logical hierarchy. Ensure lists and tables are properly tagged. Check that decorative elements are marked as artifacts. An untagged PDF, even if it looks clean visually, is not compliant.
3. Verify Reading Order
Reading order determines how content is presented to screen reader users.
Use Acrobat’s Reading Order tool to confirm content flows logically from top to bottom and left to right. Multi-column layouts often fail this test and must be corrected manually.
4. Add Alternative Text to Meaningful Images
Images that convey information must include descriptive alternative text. Decorative images should be marked as artifacts so they are ignored by screen readers.
Alt text should describe purpose, not appearance. Instead of “Image of chart,” write “Bar chart showing 25% increase in revenue from 2022 to 2023.”
5. Structure Tables Correctly
Tables must include header rows defined programmatically. Simply bolding the first row is not enough.
Each data cell must be associated with the correct header. Complex tables may require additional tagging adjustments.
Example: Why Proper Table Headers Matter
Consider the following simple table:
| Year | Revenue | Profit |
|---|---|---|
| 2022 | $1,000,000 | $200,000 |
| 2023 | $1,250,000 | $275,000 |
Visually, this table appears structured because the first row is bolded. However, bold formatting alone does not make a table accessible.
For a PDF to be Section 508 compliant, header rows must be defined programmatically. This means the header cells must be tagged as table headers (TH), not just visually styled.
If the table is not properly tagged, a screen reader may read the content as a continuous stream of text:
“Year Revenue Profit 2022 1,000,000 200,000 2023 1,250,000 275,000.”
Without header associations, users cannot determine which data belongs to which column.
When tagged correctly, a screen reader will announce each value with its associated header, such as:
“Row 2. Year: 2022. Revenue: $1,000,000. Profit: $200,000.”
This structured relationship between headers and data cells is essential for accessibility.
Complex Table Considerations
More complex tables require additional attention. For example:
| Region | Revenue | |
|---|---|---|
| 2022 | 2023 | |
| North | $500,000 | $650,000 |
| South | $500,000 | $600,000 |
In this example, “Revenue” functions as a grouped column header, while “2022” and “2023” act as sub-headers. To make this accessible:
- Header scope (row or column) must be properly defined.
- Header cells may require explicit associations with data cells.
- Merged cells should be used cautiously, as they often break structural logic.
Failure to define these relationships programmatically can result in incorrect reading order and misinterpretation of data by assistive technologies.
How to Fix Table Accessibility
In Microsoft Word:
- Use the “Header Row” option in Table Design.
- Avoid manually formatting headers with bold text alone.
- Minimize merged cells where possible.
In Adobe Acrobat Pro:
- Verify that header cells are tagged as
<TH>in the Tags panel. - Use the Table Editor to confirm header scope and associations.
- Ensure data cells (
<TD>) are correctly mapped to their respective headers.
Accessibility is based on structure, not appearance. A table that looks correct visually may still fail compliance if the underlying tagging is incomplete.
6. Make Forms Accessible
If your PDF includes form fields:
- Add clear field labels.
- Ensure tab order follows a logical sequence.
- Provide instructions and error feedback.
Form accessibility is one of the most common failure points in 508 audits.
Example: Accessible PDF Form Fields (Labels, Tab Order, Instructions, Errors)
Imagine a simple PDF form where a user requests a call back:
- Full name
- Email address
- Phone number
- Preferred contact method (Email / Phone)
- Submit button
What a non-compliant PDF often looks like (common 508 failure)
Visually, the form looks fine. But under the hood:
- The fields are unlabeled (or labels aren’t programmatically tied to the fields).
- The tab order jumps around the page randomly.
- Required fields are only marked with a red asterisk (color alone).
- If the user submits with missing data, the error message appears visually but isn’t announced to screen readers.
What a screen reader user experiences:
- “Edit. Edit. Edit.” (no idea what each field is for)
- Tabbing jumps from Email → Submit → Phone → Back to Name
- They submit the form and nothing makes sense, because the error isn’t communicated accessibly.
That’s a fail in a 508 audit.
7. Set Document Properties and Metadata
A compliant PDF should include:
- Document title (displayed in the title bar)
- Defined document language
- Proper metadata fields
This ensures assistive technologies interpret the document correctly.
8. Avoid Image-Only (Scanned) PDFs
Scanned documents are essentially images. Without Optical Character Recognition (OCR) and proper tagging, they are not accessible.
Run OCR in Acrobat and then manually verify tagging and reading order.
How to Check if Your PDF Is Section 508
Compliant Use automated accessibility checkers as a first pass. Adobe Acrobat Pro includes an Accessibility Checker that flags structural issues.
However, automated testing does not guarantee compliance. Manual review is essential.
For more comprehensive validation, tools such as ADScan can test against PDF/UA standards and provide detailed remediation guidance.
Can You Make a Microsoft Word Document Section 508 Compliant?
Yes and you should. Creating an accessible PDF starts with an accessible Word document. Word includes built-in accessibility features such as:
- Heading styles for structure
- Alt text fields for images
- Accessible table formatting
- Language settings
- Accessibility Checker
When structured properly, exporting to PDF preserves much of this accessibility, significantly reducing remediation time later.
Beyond Compliance: Why It Matters
Section 508 compliance is not simply a legal requirement. It ensures equitable access to information and reduces risk exposure from accessibility complaints or audits.
Accessible PDFs improve usability for all users, including those using mobile devices, screen magnifiers, or keyboard navigation.
Compliance is the baseline. Usability is the goal.
