PDF accessibility guidelines

The web-based accessibility guidelines are curated for applying accessibility principles on creating accessible PDF. The guidelines below are categorized by type of content present in your PDF. Based on type of content in PDF you can cut to the point in making your PDF accessible. The guidelines that do not apply to PDF documents are not present below.

Please feel free to provide any feedback via comments.

Curated accessibility guidelines for PDF

PDF layout or foundational guidelines

What to check?Respective WCAG rule
Use native/system provided tags to create elements within the PDF. Mocking an element to show something else (such as paragraph copy enlarged for “showing as” heading) will violate WCAG 1.3.1.1.3.1 Info and Relationships
The content should display in portrait or landscape orientation unless where it is essential. 1.3.4 Orientation
Ensure that content is written in a proper sequence.
E.g, a horizontal layout PDF featuring main content in the center column and secondary content in left and right columns. Sequence would be broken because screen readers would read content from left-to-right starting with first column for left-to-right languages.
1.3.2 Meaningful Sequence
Content should adjust itself (reflow) in one direction (horizontal or vertical) when content is zoomed up to 400%. Typically but not always, you would have vertical scrolling only when content is being zoomed so that users do not have to move in two directions to consume content. See width and height restrictions in the guideline.1.4.10 Reflow
The interface components or information conveying graphical objects should have at least 3:1 contrast ratio against adjacent colors.1.4.11: Non-text Contrast
All interactive elements should be accessible via keyboard alone.2.1.1: Keyboard
Ensure keyboard access is not stuck on one element or within one section. If an element can be focused via a keyboard-alone, it can also be exited using keyboard alone.2.1.2: No Keyboard Trap
Allow users to bypass blocks of content that are repeated on multiple pages of the PDF. E.g., if you have header on every page, you would need to provide a mechanism to jump directly in the content otherwise it will be a laborious task for those with limited mobility users such as keyboard-only or those using a mouth stick. 2.4.1 Bypass Blocks
Give PDF a meaningful title. Doesn’t have to be on all pages but the first page so that users know what the document is about. It’s a usability practice too so it is basically document writing 101.2.4.2: Page Titled
Elements that can be interacted with keyboard should show a visible focus when focus is on that element.2.4.7 Focus Visible
Interactive PDFs that uses multipoint or path-based gestures (e.g., select and drag), then the same operations should also be possible using single point. E.g., if you have a slider implemented that can be scrolled using touch and move to navigate through slides, you would also need to provide buttons such as previous/next for single point gestures.2.5.1: Pointer Gestures
Any clickable or tappable elements should perform its operation when click or tap is released instead of when the element is pressed or that a mechanism is available to cancel the operation “before” completion. 2.5.2: Pointer Cancellation
Set the human language of page to the language of content in the PDF. See how you can set the language of page in PDF.3.1.1: Language of Page
Ensure that any navigational items or components that have the same functionality are consistent across the PDF. E.g., the order, look and feel, etc. stays consistent across pages so that users can predict the operation when they see it repetitively.3.2.3: Consistent Navigation
3.2.4: Consistent Identification
All user interface components such as form elements, links, etc. must have programmatically determinable name and role and any values that user can set can also be programmatically set by screen readers.4.1.2: Name, Role, Value

PDF contains only text

What to check?Respective WCAG rule
Ensure that content provided doesn’t rely on shape, color, size, location on page, etc. because screen readers will not see color, know a shape, or the location of specific content. 1.3.3 Sensory Characteristics
Color is not used as sole means of conveying information. E.g., “click on red link”, “sales numbers are shown in blue”, etc. are violations of accessibility laws.1.4.1 Use of Color
Ensure minimum contrast ratio of 4.5:1 or 3:1 based on font size. Logos or decorative content are exceptions.1.4.3: Contrast (Minimum)
True text should be resizable up to 200% within the browser or PDF reader without assistive technology such as Magnifier or Zoom.1.4.4 Resize text
Always use true text unless it is essential to use a particular presentation of text via images of text. E.g., logos can have text as images of text since they are identities.1.4.5 Images of Text
Content or functionality should not change if user changes a) line height or line spacing to at least 1.5 times the font size; b) space between paras to at least 2 times font size; c) letter spacing (tracking) to at least 0.12 times the font size; d) word spacing to at least 0.16 times the font size.1.4.12 Text Spacing
Content that toggles upon focus should be dismissible, hoverable, and persistent.1.4.13 Content on Hover or Focus
Preserve the focus order in which elements can be navigated. Ideally, if you don’t change the focus order then the elements should all be in order by default.2.4.3 Focus Order
The purpose of the link should be determinable from link text alone or the surrounding context. 2.4.4 Link Purpose (In Context)
Use clear and descriptive headings that convey the purpose of the section or component clearly.2.4.6 Headings and Labels
If you have copy or parts of copy that is in different language than the document’s language, then specify that language for that portion so the screen readers can read the content in correct language to its users.3.1.2: Language of Parts

PDF contains images

What to check?Respective WCAG rule
Ensure that all images have alt text (either empty or descriptive as described in alt text guidelines for decorative vs. informative images)1.1.1: Non-text Content
Any information conveying graphical objects should have a contrast ratio of at least 3:1 against adjacent colors.1.4.11 Non-text Contrast
Ensure that any animated images within the PDF doesn’t have flashes > 3 times per second or the flash is below the general flash and red flash thresholds.2.3.1: Three Flashes or Below Threshold
If you have alt text that is in different language than the document’s language, then specify that language for that portion so the screen readers can read the content in correct language to its users.3.1.2: Language of Parts

PDF contains embedded videos

What to check?Respective WCAG rule
Video content should have captions and audio descriptions that will provide a text equivalent to those using screen readers to access content.– 1.1.1: Non-text Content
– 1.2.2: Captions (Prerecorded)
– 1.2.3: Audio Description or Media Alternative (Prerecorded)
1.2.5: Audio Description (Prerecorded)
Provide audio description and transcript for video-only content.1.2.1: Video-only (Prerecorded)
Provide captions for all live audio in synchronized media such as webinar or webcast.1.2.4: Captions (Live)
If any audio is playing automatically for more than 3 seconds, provide user controls to pause or stop the audio or provide system independent control to adjust the volume of that specific audio. i.e., reducing or increasing that specific volume would not change the system volume.1.4.2: Audio Control
Provide pause, stop, or hide option for any moving, blinking, scrolling, or auto-updating content that is lasting for more than 5 seconds.2.2.2: Pause, Stop, Hide
Ensure that any sequence within video embedded in PDF doesn’t have flashes > 3 times per second or the flash is below the general flash and red flash thresholds.2.3.1: Three Flashes or Below Threshold

PDF contains embedded forms

What to check?Respective WCAG rule
Input controls (non-text) content should have name that will provide a text equivalent to those using screen readers to understand the significance of the input elements.1.1.1: Non-text Content
Purpose of input field can be programmatically determined (e.g., by screen readers) not just visually. E.g., use proper input types (tel, email, name, password, etc.) otherwise screen readers will not be able to get correct information to users.1.3.5: Identify Input Purpose
Any user interface components should have a contrast ratio of at least 3:1 against adjacent colors.1.4.11 Non-text Contrast
Provide visible label text in programmatically accessible name. This will help screenreader users who are also seeing content avoid confusion by hearing relevant terms from screenreaders as they see on screen.2.5.3: Label in Name
Don’t change context just when an element receives focus as that can disorient users. E.g., moving focus to input B as soon as input A receives the focus; hiding the main nav and showing only sub-nav when one of the main nav item receives focus (it is acceptable to implement this functionality on click or tap.) 3.2.1: On Focus
When automatically validating the form, help user identify where the error is and help them understand how to fix it.3.3.1: Error Identification
3.3.3: Error Suggestion
Provide labels or instructions wherever user input is required.3.3.2: Labels or Instructions
Provide a mechanism to reverse submissions, validate inputs, and confirmation wherever legal commitment or financial transactions are involved that may modify or delete the data. E.g., if someone wants to make a payment to credit card, validate the inputs such as amount entered or card selected and then allow user to review, confirm, or make corrections before final submission.3.3.4: Error Prevention (Legal, Financial, Data)

PDF contains embedded audio

What to check?Respective WCAG rule
Audio (non-text) content should have transcripts that will provide a text equivalent to those using screen readers to access content.1.1.1: Non-text Content
Provide alternative text for audio-only content such as transcripts.1.2.1: Audio-only (Prerecorded)
If any audio is playing automatically for more than 3 seconds, provide user controls to pause or stop the audio or provide system independent control to adjust the volume of that specific audio. i.e., reducing or increasing that specific volume would not change the system volume.1.4.2: Audio Control

Quality assurance or testing your PDF is very important. You may use Adobe Acrobat Pro for help with some testing but it is important to note that automated QA for accessibility is not enough so a manual test pass is important to ensure a full accessibility compliance.

p.s. the audio descriptions, captions, and transcripts requirements in tables above are in review.

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