WCAG 3.3.6 Error Prevention (All): Protect Users From All Submission Errors

What This Criterion Requires

WCAG 3.3.6 extends the Level AA criterion 3.3.4 (Error Prevention for legal, financial, and data submissions) to cover all form submissions where the user enters data. This means that for every form on your website, at least one of the following must be true: submissions are reversible (the user can undo or cancel after submitting), data is checked for errors and the user is given the opportunity to correct them before final submission, or a confirmation mechanism is provided that allows the user to review and confirm the information before completing the submission. This criterion recognizes that input errors affect everyone, not just in high-stakes financial contexts. A user with a cognitive disability filling out a simple contact form deserves the same error-prevention safeguards as someone completing a bank transfer. Common implementations include a review step before submission, inline validation that catches errors before the user submits, confirmation dialogs, and undo or edit capabilities after submission. Meeting this criterion significantly reduces user frustration, support requests, and abandoned form completions.

Why It Matters

Everyone makes mistakes when filling out forms, but people with cognitive disabilities, motor impairments, and vision loss are disproportionately affected. A user with dyslexia may transpose characters in an email address. A user with a motor impairment may accidentally trigger a submit button while navigating the form. A screen reader user may not realize they selected the wrong option from a dropdown because the visual feedback was not communicated. Without error prevention mechanisms, these users may submit incorrect data without knowing it, leading to failed communications, incorrect orders, or the need to start over entirely. Even for users without disabilities, the frustration of losing form data due to an error or accidental submission is a common source of complaint. Error prevention is fundamentally about respecting users' time and reducing unnecessary friction in digital interactions. It also reduces support costs for organizations by catching problems before they generate support tickets.

Common Failures and How to Fix Them

<form action="/submit" method="POST">
  <label for="msg">Message</label>
  <textarea id="msg" name="message"></textarea>
  <button type="submit">Send</button>
</form>

<form action="/submit" method="POST">
  <label for="msg">Message</label>
  <textarea id="msg" name="message"></textarea>
  <button type="button" onclick="showReviewStep()">Review before sending</button>
</form>
<!-- Review step shows a summary of all entered data -->
<!-- with Edit and Confirm buttons -->

<input type="email" name="email" required>
<!-- No validation until form submit -->

<input type="email" name="email" required
  aria-describedby="email-error"
  aria-invalid="false">
<span id="email-error" role="alert"></span>
<script>
  // Validate on blur and show inline error
  input.addEventListener('blur', validateEmail);
</script>

<!-- After submit: -->
<p>Thank you! Your response has been recorded.</p>
<!-- No edit or undo option -->

<!-- After submit: -->
<p>Your response has been recorded.</p>
<p><a href="/submissions/123/edit">Edit your response</a>
  or <button onclick="undoSubmission(123)">Undo</button>
  (available for 30 minutes)</p>

How to Test

1. Identify all forms on the site and submit each one. Verify that at least one error prevention mechanism is in place: review step, inline validation, confirmation dialog, or undo capability.
2. Test whether the form provides inline validation feedback as you fill out fields, catching errors before final submission.
3. After submitting a form, check whether you can edit or undo the submission within a reasonable timeframe.
4. Deliberately enter incorrect data and verify the form alerts you to errors before processing the submission.

CMS-Specific Guidance

This criterion commonly causes issues on these platforms:

• Wordpress Accessibility Checklist
• Shopify Accessibility Checklist
• Squarespace Accessibility Checklist
• Wix Accessibility Checklist
• Webflow Accessibility Checklist

Further Reading

• Accessible Forms Guide
• Wcag Explained Plain English
• Eaa Compliance Checklist 2026

Related WCAG Criteria

• WCAG 3.3.4
• WCAG 3.3.1
• WCAG 3.3.3