A PDF Accessibility check before publishing catches barriers that prevent people using screen readers, keyboard navigation, or high-contrast modes from accessing your content. An inaccessible PDF may look fine visually while being completely unusable for a significant portion of the audience. Running an automated accessibility check is the first step toward compliance with standards like WCAG 2.1 and PDF/UA.
Automated checkers cannot guarantee full accessibility. They scan for machine-detectable issues: missing alt text, untagged content, insufficient color contrast, and illogical reading order. Human review is still needed for issues that require judgment, such as whether alt text accurately describes an image or whether the reading order matches the intended reading sequence. The automated check catches the low-hanging problems so the human reviewer can focus on the judgment-intensive ones.
WukongPDF's PDF Compliance tools include accessibility validation for documents before publication.
Running Acrobat Pro's Accessibility Checker
Open the PDF in Acrobat Pro and go to Tools, then Accessibility. Select Full Check. In the accessibility checker options dialog, choose the checking standard: WCAG 2.1 Level AA is the most widely adopted standard for web and document accessibility. Check all categories: Document, Page Content, Forms, Tables and Lists, Alternate Text, and Headings. Click Start Checking.
Acrobat scans the PDF and displays results in the Accessibility Checker panel. Issues are categorized by severity. Failures indicate clear accessibility violations that must be fixed. Warnings indicate potential issues that need manual review. Passes confirm that a specific check was satisfied. The report is interactive. Click any failure or warning to see which page elements triggered it and access the tools to fix it.
Understanding and Fixing Common Accessibility Failures
Missing alternate text for images is the most common failure. Every image in the PDF needs alt text that describes its content for screen reader users. In Acrobat Pro, right-click an image flagged in the accessibility report, choose Edit Alternate Text, and type a concise description. For decorative images that convey no information, mark them as decorative artifacts so screen readers skip them.
Untagged content is the second most common failure. PDF tags define the document structure: headings, paragraphs, lists, tables. Without tags, a screen reader cannot navigate the document logically and reads content in whatever order it appears in the PDF's internal data stream, which may not match the visual reading order. Tag the document using Acrobat Pro's Autotag Document feature under the Accessibility tool. Autotagging uses content analysis to identify headings, paragraphs, and lists, then adds the corresponding tags.
Fixing Reading Order and Heading Hierarchy
After autotagging, verify the reading order. Open the Tags panel under View, Show/Hide, Navigation Panes, Tags. The tag tree shows the document structure. Expand the tree and confirm that headings appear in the correct hierarchical order: H1 first, then H2, H3, and so on. A document that jumps from H1 to H3 without an intervening H2 confuses screen reader navigation.
Drag tags in the tree to reorder them if the reading order is incorrect. The tag order defines the sequence in which screen reader software presents the content. The visual order on the page and the tag order in the tree should match. When they do not, screen reader users hear content in an order that differs from what visual readers see, which is disorienting and can make the document impossible to understand.
Checking Color Contrast and Accessibility
The accessibility checker reports text that may have insufficient contrast against its background. The WCAG 2.1 Level AA standard requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text. Acrobat's checker estimates contrast based on the text color and the detected background color, but the estimate can be inaccurate for text over gradients or images.
For accurate contrast verification, use a dedicated contrast checker tool. Take a screenshot of the questionable text area and upload it to a contrast analyzer. If the contrast fails, change the text color or background color in the source document and re-export the PDF. Fixing contrast issues in the source document is easier and more reliable than attempting to adjust colors in the PDF directly.
| Check Category | What It Validates | Common Failures |
|---|---|---|
| Document structure | Tagged content, reading order, heading hierarchy | Missing tags, wrong reading order |
| Content accessibility | Alt text on images, table headers, link descriptions | Missing alt text, empty table headers |
| Color and contrast | Text-background contrast ratio, color-only information | Low contrast text, color-coded only content |
Re-Checking After Fixes
After fixing all reported issues, run the accessibility checker again. Some fixes may introduce new issues. Adding tags can change the reading order. Adding alt text to one image may reveal that another image on the same page was also untagged. The re-check confirms that all fixes were applied correctly and that no new problems were introduced.
Save the accessibility report alongside the final PDF as documentation of compliance. For documents subject to regulatory accessibility requirements, the report serves as evidence that an accessibility evaluation was performed and all identified issues were addressed. The report does not guarantee accessibility, but it demonstrates due diligence in the accessibility review process.
An automated accessibility check is the fastest way to identify the most common PDF accessibility barriers. The check takes under a minute, and the results guide the fixes needed to make the document usable by the widest possible audience.
Documenting Accessibility Compliance for Audiences
When a PDF is published publicly, accessibility compliance may be required by regulation. The accessibility report generated by Acrobat Pro serves as a compliance record. Save the report alongside the published PDF and include a brief accessibility statement in the document metadata.
When it comes to document workflows, for documents subject to Section 508 or the European Accessibility Act, the report demonstrates that an evaluation was performed and issues addressed. The report does not guarantee compliance but shows due diligence in the review process.
Accessibility checking should be performed on the final exported PDF, not the source document. The export process can introduce issues not present in the source, such as missing tags, incorrect reading order, or font embedding problems affecting screen reader compatibility.
During typical workflows, when it comes to document workflows, for organizations producing multilingual documents, accessibility checks should be performed on each language version separately. Translation can introduce reading order changes, and the checker must evaluate each version independently against the appropriate language settings.
In practice, the accessibility report is a living document updated each time the PDF is revised. An auditor reviewing the document accessibility trail should see a sequence of reports showing progressive improvement as issues are identified and resolved.
Accessible PDFs benefit all users. Properly tagged documents support better text reflow on mobile devices, more accurate text extraction, and improved search engine indexing. The investment in accessibility pays dividends across the entire user base.
In practice, the accessibility checker in Acrobat Pro covers over thirty specific checks spanning document structure, content, and formatting. Understanding what each check validates helps prioritize fixes when the report contains multiple failures.
Document language specification is a commonly overlooked accessibility requirement. The PDF metadata must declare the document primary language so screen readers can select the correct pronunciation rules.
Tables present particular accessibility challenges. Each table needs header rows identified, summary text describing the table purpose, and correct cell-to-header associations for screen reader navigation.
The accessibility report should be reviewed by someone who uses assistive technology at least once during the document development cycle. Automated checks catch machine-detectable issues. User testing catches the rest.
For forms, every field needs a tooltip that screen readers announce when the field receives focus. Required fields should be marked as required in both the visual label and the field properties.
PDF/UA compliance goes beyond basic accessibility to ensure the document meets the ISO standard for universally accessible PDF. The PDF/UA standard is stricter than WCAG in some areas, particularly regarding tagged content structure.
Accessibility fixes made in Acrobat Pro persist only in that copy of the PDF. If the document is regenerated from the source, the fixes must be reapplied. Fixing accessibility issues in the source document prevents this rework.
Across most tools, the time required to make a PDF accessible varies with document complexity. A simple text document may need only autotagging and alt text review. A complex document with forms, tables, and multimedia may require hours of remediation.
Accessibility is not a checkbox to tick at the end of document creation. It is a design principle that, when integrated into the document workflow from the start, produces better documents for all readers. A properly tagged PDF with a logical heading structure, descriptive alt text, and correct reading order is easier to navigate for everyone, regardless of ability.
An automated accessibility check transforms PDF compliance from a guessing game into a systematic process. The report identifies every machine-detectable issue, and the human reviewer addresses the judgment-intensive ones. Together they produce a document accessible to the widest possible audience.