How Do I Validate a PDF Against PDF/UA?

To validate a PDF against PDF/UA (ISO 14289), run it through a dedicated validator such as PAC 2024 (free, from the PDF/UA Foundation), veraPDF (open source, 108 machine-checkable rules), or Adobe Acrobat Pro's built-in accessibility checker. These tools test your document against the structural and semantic requirements defined in the PDF/UA standard, reporting failures that must be fixed before the document can be considered conformant. No single tool catches everything — full validation requires both automated checks and manual review of conditions that software cannot evaluate on its own.

If your university is working toward compliance with WCAG 2.1 and the April 2027 DOJ ADA Title II deadline (extended from 2026 via the IFR), PDF/UA validation is one of the most concrete steps you can take. It transforms "is this PDF accessible?" from a subjective question into a measurable, repeatable process.

What PDF/UA Validation Actually Tests

PDF/UA defines the technical requirements that a tagged PDF must meet to be considered accessible. These requirements cover tag structure, reading order, alternative text, metadata, font encoding, color contrast annotations, and more. The Matterhorn Protocol — maintained by the PDF Association — translates these requirements into 31 checkpoints containing 136 individual failure conditions.

The critical distinction for anyone doing validation work is between the two types of failure conditions:

• Machine-checkable conditions — These can be detected automatically by software. Examples include missing document title metadata, untagged content, figures without alternative text attributes, and missing language declarations. Roughly 89 of the 136 Matterhorn Protocol conditions fall into this category.
• Human-checkable conditions — These require a person to evaluate. Software can flag that an image has alt text, but only a human can judge whether that alt text is accurate and meaningful. Similarly, a tool can verify that reading order tags exist, but only a human can confirm the order makes logical sense. The remaining 47 conditions require human judgment.

This is why validation is a two-phase process: run the automated tools first to catch the structural issues, then manually review the conditions that software cannot assess.

PAC 2024: Step-by-Step Validation

PAC (PDF Accessibility Checker) from the PDF/UA Foundation is the most widely used free validator for PDF/UA. The 2024 version supports both PDF/UA-1 and PDF/UA-2.

Step 1: Download and install. PAC 2024 is available free from the PDF/UA Foundation website. It runs on Windows natively; Mac and Linux users can run it through a compatibility layer or a virtual machine.

Step 2: Open your PDF. Launch PAC and click "Open PDF" or drag your file into the window.

Step 3: Run the full check. Click "Start Check." PAC tests the document against all machine-checkable Matterhorn Protocol conditions and generates a detailed report within seconds for most documents.

Step 4: Review the results. PAC organizes findings by checkpoint category — document structure, text, graphics, headings, tables, lists, and more. Each failure links to the specific Matterhorn Protocol condition that was violated, making it straightforward to look up the requirement and understand what needs to change.

Step 5: Use the screen reader preview. PAC includes a built-in screen reader simulation that shows exactly how assistive technology would interpret the document. This is invaluable for understanding reading order issues that the automated check flags.

Step 6: Fix and revalidate. After making corrections in your authoring tool or PDF editor, run PAC again. Repeat until all machine-checkable conditions pass, then perform manual review of the human-checkable conditions.

veraPDF: Open Source With 108 Rules

veraPDF is an open-source validator developed with support from the PDF Association and the veraPDF Consortium. While originally built for PDF/A archival validation, it now includes a comprehensive PDF/UA validation profile with 108 machine-checkable rules.

What makes veraPDF particularly useful for universities:

• Batch processing. veraPDF includes a command-line interface that can validate entire directories of PDFs in a single run, outputting results as structured XML or HTML reports. For a department with thousands of documents, this is essential.
• CI/CD integration. The command-line tool can be incorporated into automated workflows, so documents are validated before they reach an LMS or public repository.
• Transparent rule definitions. Every rule maps to a specific PDF/UA clause and Matterhorn Protocol checkpoint. The validation logic is open source, so you can inspect exactly what each rule tests.
• Cross-platform. veraPDF runs on Windows, Mac, and Linux via Java.

To run a basic validation: install veraPDF, select the PDF/UA-1 profile, and point it at your file or directory. The output report lists every rule violation with its severity and the relevant standard clause.

Adobe Acrobat Pro Accessibility Checker

Most faculty and staff already have access to Adobe Acrobat Pro, making its built-in accessibility checker the most convenient starting point.

Navigate to Tools, then Accessibility, then "Full Check." Select "PDF/UA-1" as the checking standard if available, or use the default WCAG-based profile. Acrobat tests for tagged structure, reading order, alt text, table headers, bookmarks, and other common requirements.

Acrobat's checker is good for individual document review and quick fixes, since you can often repair issues directly within Acrobat's Tags panel and Accessibility tools. However, it has some limitations compared to PAC and veraPDF:

• It does not cover all 89 machine-checkable Matterhorn Protocol conditions.
• It does not support batch validation across multiple files.
• Some checks produce ambiguous results that require cross-referencing with PAC or veraPDF to confirm.

For a thorough comparison of these and other tools, see our guide to the best PDF accessibility checkers.

Common Validation Failures and How to Fix Them

Across thousands of university documents, certain PDF/UA failures appear far more often than others.

Missing document title. The document's metadata must include a title, and the PDF must be set to display the title (not the filename) in the title bar. Fix this in File, then Properties, then Description in Acrobat, or set it in your authoring tool before export.

Untagged content. Every piece of visible content must be wrapped in a structure tag, or explicitly marked as an artifact (for decorative elements like page borders or watermarks). Use Acrobat's Reading Order tool or the Tags panel to tag orphaned content.

Figures without alt text. Every <Figure> tag must have an Alt attribute. Purely decorative images should be marked as artifacts instead. This is the single most common failure in academic documents.

Incorrect heading hierarchy. Headings must follow a logical nesting order — H1 followed by H2, not H1 followed by H3. Most authoring tools enforce this if you use built-in heading styles rather than manual formatting.

Tables without headers. Data tables must use <TH> tags with appropriate Scope attributes. See our detailed guide on fixing table headers for step-by-step instructions.

Missing language declaration. The document must declare its primary language, and any passages in a different language must be tagged with the appropriate Lang attribute. Set the document language in File, then Properties, then Advanced in Acrobat.

Batch Validation for Large Document Libraries

Individual file validation does not scale when a department has hundreds or thousands of PDFs across course sites, policy repositories, and public web pages. Batch validation is the practical answer.

veraPDF CLI is the most accessible option for batch work. A single command can validate every PDF in a directory tree and produce a consolidated report. This lets you triage your document library by severity — fix the most critical failures first, then work through the rest systematically.

Scripted workflows using veraPDF or PAC's command-line mode can be scheduled to run nightly or weekly, catching new documents as they are added to shared drives or LMS course sites.

Prioritization matters. Not every document needs immediate attention. Start with high-traffic materials — syllabi, assignment instructions, publicly posted policies — and work outward. A phased approach is more sustainable than attempting to remediate everything at once.

For institutions managing large volumes of PDFs, Aelira's PDF remediation tools automate both validation and repair. Documents are checked against PDF/UA requirements on upload, failures are flagged with plain-language explanations, and many common issues — missing alt text, heading structure, table headers, language declarations — are fixed automatically. This turns a months-long manual project into a workflow that keeps pace with your content production.

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