The following steps use Adobe Acrobat Pro DC software for checking and applying accessibility standards (see Create and verify PDF accessibility for more detail explanation).
Key Document Properties (Title, Language, View option)
Open Document Properties (Ctrl + D) or go to File menu > select Properties
Perform optical character recognition (OCR) to ensure text is searchable. If PDF was converted from authoring software (such as Microsoft Word) you can skip this step.
Go to Tools menu > Select Enhance > Recognize text in this file.
Document Structured and Reading Order
Logical structure helps assistive technology users navigate content. Tags identify elements such as headings, paragraphs, images, tables and other page elements necessary for screen readers to make sense of a PDF’s text. If you are unsure if the PDF is already tagged, go to Document Properties (Ctrl +D) and check lower left-hand corner of the Description tab for indicator set to Yes.
To automate tagging of PDF document, use Acrobat’s Autotag Document feature. Go to Tools > Accessibility > select Autotag Document option.
For help with fixing tags, see Edit document structure with the Content and Tags panels (Acrobat Pro).
For detail steps for confirming reading order, see Reading Order tool for PDFs (Acrobat Pro)
It is recommended for larger documents to add bookmarks to aid navigation of content.
Alternate Text for Images
WebAIM provides guidelines for creating appropriate alternate text which include:
To set alt text for graphics in a PDF file, go to Tools > Accessibility > Set Alternate Text.
Note: It is not necessary to provide alternate text if the image is identified and described by surrounding text, either in a caption or nearby paragraphs or if the image is purely decorative. In such cases, use a null (empty) tag (i.e. enter double quotes ””).
Do not use Security that interferes with assistive technology
Remove any password protection and do not use PDF/A sub format as these settings prevent extracting text which is necessary for screen readers to navigate the underlining text of the document.
Run Acrobat’s Accessibility Full Check tool and address any issues that may arise. Proceeding through the above steps should minimize possible issues that may appear but each PDF is unique and may need additional remediation.
Go to Tools menu > Accessibility > select Full Check option