Level AAAWCAG 2.0

3.3.6 Error Prevention (All)

For pages requiring the user to submit information, submissions are reversible, checked for errors, or confirmed before finalizing.

Last reviewed: September 9, 2026

Understanding 3.3.6

This is the AAA-level generalization of 3.3.4, extending the same reversibility, review, or confirmation safeguards to any form submission requiring user information, not just legal, financial, or data-modifying ones. It exists to minimize the impact of mistakes for all users on every form, not only high-stakes transactions.

How to Meet It

Apply the same techniques used for 3.3.4 (a reversible action, a review step, or explicit confirmation) to every form on the site that collects user-submitted information, even low-stakes ones such as a newsletter signup or a comment form.

Code Examples

INCORRECT

<form onsubmit="postComment()">
  <textarea name="comment"></textarea>
  <button type="submit">Post</button>
</form>
<!-- No opportunity to review or edit the comment before it's published -->

CORRECT

<form onsubmit="showPreview(); return false;">
  <textarea name="comment"></textarea>
  <button type="submit">Preview</button>
</form>
<div id="preview" hidden>
  <p>Review your comment:</p>
  <blockquote id="preview-text"></blockquote>
  <button onclick="postComment()">Confirm & Post</button>
  <button onclick="editComment()">Edit</button>
</div>

Frequently Asked Questions

How is this different from 3.3.4?

3.3.4 (AA) only applies to pages involving legal commitments, financial transactions, data modification/deletion, or test submissions. 3.3.6 (AAA) applies the same protection to every form submission on the site, regardless of the stakes involved.

Related Success Criteria

3.3.1 Error Identification 3.3.2 Labels or Instructions 3.3.3 Error Suggestion 3.3.4 Error Prevention (Legal, Financial, Data)

Quick Facts

Criterion3.3.6
LevelAAA
IntroducedWCAG 2.0

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