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PDF/UA vs WCAG: which one do you need?
Short answer: The ADA Title II rule requires WCAG 2.1 Level AA, so that is the legal target. PDF/UA (ISO 14289) is the technical standard for how an accessible PDF file is built. Meeting PDF/UA is the practical way to meet most of WCAG's requirements for a PDF's structure, but WCAG also covers things PDF/UA does not, such as color contrast and clear link text.
How they fit together
| Aspect | WCAG 2.1 | PDF/UA-1 |
|---|---|---|
| What it is | W3C guidelines for accessible web content | ISO 14289-1, a file-format standard for accessible PDFs |
| Required by ADA Title II rule | Yes, Level AA | Not named in the rule |
| Covers | Any web content, including documents | PDF files only |
| Structure (tags, headings, tables) | Yes (1.3.1, 1.3.2) | Yes, in technical detail |
| Image text alternatives | Yes (1.1.1) | Yes |
| Color contrast | Yes (1.4.3) | No |
| Meaningful link text | Yes (2.4.4) | Partly |
| Fonts and Unicode mapping | Indirectly | Yes, in detail |
In practice
- Build to PDF/UA. It tells you exactly how tags, alternative text, fonts and metadata must be stored so assistive technology can use them.
- Check against WCAG. Confirm contrast, link text, reading order and that the content makes sense when heard.
What “machine-checkable” means
Software can confirm that a figure has alternative text, but not that the text is right. It can confirm headings are tagged, but not that they reflect the document’s meaning. That is why every remediation, automated or manual, should end with a person listening to the document with a screen reader.
Our validation uses veraPDF’s PDF/UA-1 profile, and our reports list the items a person still needs to check.
Frequently asked questions
- If my PDF passes PAC, does it meet WCAG?
- Not necessarily. PAC tests the machine-checkable PDF/UA rules and some WCAG-related checks. Human checks of reading order, image descriptions and meaning are still required.
- What is the Matterhorn Protocol?
- A document from the PDF Association that lists every way a PDF can fail PDF/UA: 136 failure conditions in 31 checkpoints, of which 87 can be determined by software.