PDF/UA: the standard for accessible PDFs, explained clearly

What is PDF/UA?

PDF/UA stands for Universal Accessibility and is the international standard for accessible PDFs, defined in ISO 14289. It precisely defines the technical properties a PDF must have so that assistive technologies such as screen readers, refreshable braille displays and text-to-speech software can reliably interpret and present its content.

Crucially, PDF/UA does not govern how a document looks; it governs how the document is structured internally. Two PDFs can look identical on screen, but only the one with a complete structural layer—including tags, reading order and alt text—is genuinely accessible to screen-reader users.

PDF/UA is not itself a law. Legal obligations arise from legislation such as the German Accessibility Strengthening Act (BFSG) and BITV 2.0, which reference technical requirements through the European standard EN 301 549. PDF/UA is the established way to implement those requirements correctly in PDF.

PDF/UA-1 and PDF/UA-2 compared

The standard has two parts, which differ primarily in their technical foundations:

PDF/UA-1 (ISO 14289-1)

The first part of the standard was published in 2012 and is based on PDF 1.7. PDF/UA-1 remains widely used: most existing accessible PDFs and many validation tools support this version.

PDF/UA-2 (ISO 14289-2)

The second part was published in 2024 and is based on PDF 2.0. It uses the revised PDF 2.0 structure model, with a more clearly defined namespaced tag set, more precise rules for annotations and links, and structured markup for mathematical formulae using MathML. PDF/UA-2 represents the current state of the art for new documents, while PDF/UA-1 documents remain valid and usable.

What are the core requirements of PDF/UA?

Regardless of the version, PDF/UA requires all meaningful content to have a machine-readable structure. Its core requirements are:

• Tagged content (tag tree): Every meaningful element—including headings, paragraphs, lists, tables, figures and links—must use the appropriate structure element. The tag tree represents the document’s semantic structure and provides the foundation for assistive technology.
• Logical reading order: The order of the tags must follow the meaningful reading sequence, including in multi-column layouts, sidebars and information boxes. Content placed side by side visually still needs an unambiguous sequence for text-to-speech output.
• Alt text for graphics: Images, diagrams and other graphical elements that convey information need alt text describing their content or purpose.
• Marking artefacts: Purely decorative elements—including headers, footers, page numbers, background graphics and decorative lines—must be marked as artefacts so that screen readers skip them rather than interrupting the reading flow.
• Document title and language: The metadata must contain a meaningful document title to display instead of the file name. The primary language must also be declared, and changes of language within the text must be marked so that text-to-speech software uses the correct pronunciation.
• Unicode mapping: Every character must map unambiguously to Unicode so that text-to-speech software, search and copy functions can process the text reliably.
• Correct table and list structures: Tables need properly marked header cells and unambiguous associations between header and data cells. Lists need genuine list structures rather than paragraphs that simply begin with dashes.

How are PDF/UA and WCAG related?

In short: WCAG defines the success criteria; PDF/UA defines their technical implementation in PDF. The Web Content Accessibility Guidelines (WCAG) set technology-neutral requirements for digital content, including both websites and documents. PDF/UA translates those requirements into specific, testable rules for PDF technology.

The two standards complement rather than replace each other. A PDF/UA-conforming document meets the structural requirements, while WCAG adds content-related criteria such as sufficient colour contrast and meaningful link text. Combining PDF/UA conformance with WCAG evaluation is therefore the reliable route to accessible PDFs. Learn how the criteria apply to PDFs in our guide WCAG for PDF documents.

What role do EN 301 549 and BFSG play?

The EN 301 549 is the European standard for accessible information and communications technology. Chapter 10 covers non-web documents, including PDFs, and incorporates the relevant WCAG success criteria.

The BFSG implements the European Accessibility Act (EAA) in German law. Since 28 June 2025, it has applied to the products and services listed in Section 1 BFSG, including banking, e-commerce and passenger transport. It does not cover every business, but whenever a service is within scope, associated PDFs such as contracts, product information and statements must also be accessible. EN 301 549 is the principal technical reference. For public-sector bodies, BITV 2.0also applies and likewise references EN 301 549. For details about scope and deadlines, see BFSG and accessible PDFs and our page for Authorities and public administration.

How to check PDF/UA compliance?

A robust conformance assessment always combines automated validation with human evaluation.

Automated validation

Established tools like veraPDF and the PDF Accessibility Checker (PAC) automatically validate formal requirements: Is a tag tree present? Are the document title and language set? Can every character map to Unicode? Is any alt-text entry missing? Software can reliably determine these syntactic criteria.

The Matterhorn Protocol as a test catalogue

The Matterhorn Protocol published by the PDF Association sets out the PDF/UA-1 requirements in a structured test catalogue containing 31 checkpoints and 136 failure conditions. It explicitly distinguishes conditions that software can test automatically from those that require human judgement, making it a shared reference for validation tools and manual audits.

Human evaluation

No automated test alone can decide whether alt text accurately describes an image, whether the reading order makes sense or whether a table structure reflects the meaning of its data. People must evaluate these semantic questions, ideally supported by a practical screen-reader test.

How Accessful supports PDF/UA conformance

Accessful automatically audits and remediates PDFs in line with PDF/UA-2, WCAG 2.2 and EN 301 549. Its AI adds the structural layer—including tags, reading order, alt text, and table and list structures—while leaving the document’s layout and content unchanged. Results are typically available in seconds, even when processing thousands of documents in batches.

Every remediated document comes with an audit-ready report as evidence for compliance reviews and audits. Learn how this works on PDF accessibility with AI and How it works —or try the free PDF check with your own documents.