PDF/UA is the ISO standard that defines how an accessible PDF is built — its tags, structure, reading order, and metadata. It comes in two editions: PDF/UA-1 (ISO 14289-1), published in 2014 and built on PDF 1.7, and PDF/UA-2 (ISO 14289-2), published in March 2024 and built on PDF 2.0 (ISO 32000-2). If you already produce PDF/UA-1 files today, the short answer is reassuring: you do not need to rush a migration. But it helps to understand what changed and where the standard is heading.
This guide explains the differences in plain English, when (and whether) PDF/UA-2 matters for your organization, and the reality of tool support in 2026.
A quick refresher: what PDF/UA actually does
PDF/UA stands for "PDF/Universal Accessibility." It is a technical conformance standard — a set of rules a PDF must satisfy so that assistive technology, like a screen reader, can interpret it correctly. That includes a logical structure (the tag tree and reading order), alternative text for images, correct language metadata, and the absence of traps that break navigation.
It is worth being clear about how PDF/UA relates to the rules most teams are required to meet. WCAG defines what accessibility means at the content level (perceivable, operable, understandable, robust). PDF/UA defines how to implement that inside a PDF file. The two are complementary, not competing — which is exactly why our WCAG 2.2 and PDF/UA pillar guide treats them together. A file can conform to PDF/UA and still need a human to check that, say, the alt text is actually meaningful.
It is also distinct from PDF/A (ISO 19005), the archiving standard. PDF/A is about long-term preservation, not accessibility, even though its "a" conformance levels require tagging. If that distinction is fuzzy, our PDF/A vs PDF/UA explainer walks through it.
PDF/UA-1 (ISO 14289-1): the baseline most files use today
PDF/UA-1 was published in 2014 and is anchored to PDF 1.7. For more than a decade it has been the reference for accessible PDFs. When a vendor says a document is "PDF/UA compliant," they almost always mean PDF/UA-1.
PDF/UA-1 introduced the requirements practitioners now treat as table stakes:
- A complete, properly nested tag tree describing headings, paragraphs, lists, tables, and figures.
- A defined reading order that matches the document's logical flow.
- Alternative text on meaningful images and a way to mark decorative content as artifacts.
- Correct language declarations and document metadata.
- No reliance on color alone, no inaccessible navigation, and no untagged content.
To test conformance against these rules, the PDF Association maintains the Matterhorn Protocol — a catalog of failure conditions and checkpoints. Matterhorn was written for PDF/UA-1, and most automated checkers (including ours) still report against it.
PDF/UA-2 (ISO 14289-2): what the 2024 edition changes
PDF/UA-2 was published in March 2024 and is built on PDF 2.0 (ISO 32000-2) rather than PDF 1.7. PDF 2.0 modernized the underlying file format, and PDF/UA-2 takes advantage of those capabilities. The headline improvements:
- Alignment with PDF 2.0. PDF/UA-2 uses the newer structure model and is designed to work with PDF 2.0 features, rather than retrofitting accessibility onto the older 1.7 format.
- Namespaces and a simpler, more flexible structure. PDF 2.0 supports structure-element namespaces, so tags can carry clearer, standardized semantics. This reduces the historic reliance on role maps — the awkward mechanism PDF/UA-1 used to translate custom tag names back to standard ones.
- Native MathML for formulas. Mathematical content can be represented with MathML inside the structure tree, instead of leaning solely on alt text to describe an equation. This is a meaningful step for STEM, education, and technical publishing.
- Improved tables and annotations. The handling of complex tables and of annotations (links, comments, form-related markup) is clarified and strengthened.
- Pronunciation hints. Authors can supply guidance so assistive technology pronounces names, acronyms, and unusual terms correctly.
- Document-level associated files. PDF/UA-2 builds on PDF 2.0's associated-files feature, letting a document attach related resources (such as a long description or source data) at the document level in a standardized way.
The net effect is a standard that expresses accessible structure more directly and with fewer workarounds — useful especially for math-heavy and structurally complex documents.
PDF/UA-1 vs PDF/UA-2 at a glance
| Aspect | PDF/UA-1 (ISO 14289-1) | PDF/UA-2 (ISO 14289-2) |
|---|---|---|
| Published | 2014 | March 2024 |
| Base PDF format | PDF 1.7 | PDF 2.0 (ISO 32000-2) |
| Structure model | Standard tag set + role maps | Namespaced tags; reduced role-map reliance |
| Math content | Alt text describing the formula | Native MathML in the structure tree |
| Tables & annotations | Supported | Clarified and improved |
| Pronunciation | Not addressed | Pronunciation hints supported |
| Associated files | Limited | Document-level associated files |
| Testing reference | Matterhorn Protocol | Matterhorn updates evolving for 2.0 |
| Adoption in 2026 | Widely used, broad tool support | Emerging; tool support still maturing |
Do you need to migrate to PDF/UA-2 today?
For most organizations, no — not yet, and not as an urgent project. A few practical reasons:
- Regulations point at WCAG, not a specific PDF/UA edition. The laws that drive PDF accessibility — the ADA Title II web rule, Section 508, Section 504, the EAA via EN 301 549 — reference WCAG (2.0, 2.1, or 2.2 AA depending on the rule). None of them require PDF/UA-2 specifically. A well-built PDF/UA-1 file that meets the applicable WCAG level still satisfies these obligations.
- PDF/UA-1 is not deprecated. ISO 14289-1 remains a valid, current standard. PDF/UA-2 is an addition, not a replacement that retires the first edition.
- Tooling needs to catch up. Authoring tools, validators, and the assistive technologies themselves are still maturing their PDF 2.0 and PDF/UA-2 support. Producing files that exercise PDF/UA-2's new features only pays off when the tools your readers use can interpret them.
There are situations where PDF/UA-2 is worth tracking sooner: if you publish heavy mathematical or scientific content and want native MathML, if you generate structurally complex documents that strain PDF/UA-1's role-map approach, or if you have a long-term content pipeline you would rather build on PDF 2.0 from the start.
This is general information, not legal advice. Your specific obligations depend on your jurisdiction and the regulation that applies to you.
The state of tool support in 2026
PDF/UA-2 is real and published, but the ecosystem around it is still settling. Many widely used authoring tools default to PDF 1.7 output and PDF/UA-1 conformance. Automated checkers largely validate against Matterhorn as written for PDF/UA-1, with PDF 2.0–aware updates arriving incrementally. Screen readers and other assistive technology continue to improve their handling of PDF 2.0 structures over time.
The pragmatic stance for now is the same one that has always served accessibility teams well: build documents that are genuinely well-structured, validate them, and have a human confirm the result. A clean PDF/UA-1 file — correct tags, logical reading order, meaningful alt text, real headings, accessible tables — is most of the way to PDF/UA-2 already. When you do migrate, that solid structure is exactly what carries over.
Key takeaways
- PDF/UA = ISO 14289. PDF/UA-1 (2014) is based on PDF 1.7; PDF/UA-2 (March 2024) is based on PDF 2.0.
- PDF/UA-2 adds native MathML, pronunciation hints, namespaced structure with less role-map reliance, improved tables and annotations, and document-level associated files.
- PDF/UA defines how accessibility is implemented; WCAG defines what it means — and the laws that apply to you reference WCAG, not a specific PDF/UA edition.
- Most teams do not need to migrate to PDF/UA-2 urgently; a clean PDF/UA-1 file that meets the required WCAG level is compliant, and tool support for 2.0 is still maturing.
- Focus on solid structure today — it carries forward to PDF/UA-2 when the ecosystem catches up.
Frequently asked questions
When was PDF/UA-2 published?+
ISO 14289-2 (PDF/UA-2) was published in March 2024 and is built on the PDF 2.0 (ISO 32000-2) file format.
