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Understandable WCAG 3.3.4

3.3.4 Error Prevention (Legal, Financial, Data)

For web pages that cause legal commitments or financial transactions, submissions are reversible, checked, or confirmed.

Level AA Moderate WCAG 2.0 (new) WCAG 2.1 WCAG 2.2

What this rule means

WCAG 3.3.4 requires that for forms involving legal commitments (contracts, agreements), financial transactions (purchases, transfers), or user-controllable data (deleting an account), at least one of three safeguards is in place: submissions are reversible, data is checked for errors before final submission, or the user can review and confirm before submission.

This protects users from costly mistakes that would be difficult or impossible to undo.

Why it matters

Users with motor impairments may accidentally click submit. Users with cognitive disabilities may not realize they are committing to a purchase. Screen reader users may miss important details. Error prevention safeguards protect all users from irreversible mistakes.

For legal and financial transactions, the consequences of errors can be severe — financial loss, unwanted contracts, or permanent data deletion.

Related axe-core rules

There are no automated axe-core rules for this criterion. Manual review of critical forms is required.

How to test

  • Identify all forms that involve legal, financial, or data-deletion actions.
  • Verify at least öne safeguard: reversibility, error checking, or confirmation step.
  • Test the confirmation step with a screen reader to ensure all details are accessible.
  • Verify that the undo/cancel mechanism actually works.

How to fix

<!-- Confirmation page before final submission -->
<h2>Review Your Order</h2>
<table>
  <tr><td>Product</td><td>Widget Pro</td></tr>
  <tr><td>Price</td><td>$49.99</td></tr>
  <tr><td>Shipping</td><td>123 Main St, City</td></tr>
</table>
<form action="/submit-order" method="post">
  <a href="/cart">Go back and edit</a>
  <button type="submit">Confirm and Pay</button>
</form>

<!-- Undo mechanism -->
<div role="alert">
  <p>Your account has been scheduled for deletion.</p>
  <button onclick="cancelDeletion()">Undo — Cancel deletion</button>
  <p>You have 30 days to reverse this action.</p>
</div>

Common mistakes

  • One-click purchases without any confirmation.
  • Permanent data deletion without an undo option or confirmation.
  • Confirmation dialogs that don't include all relevant details for review.
  • No way to go back and edit submitted information.

Resources