SC 3.3.4: Error Prevention (Legal, Financial, Data)
Normative Text
For Web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses, at least one of the following is true: Reversible: Submissions are reversible; Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them; Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.
Understanding 3.3.4
High-stakes forms (purchases, legal agreements, exam submissions, data deletion) must let users review, correct, or reverse the action.
How to Comply
E-commerce checkouts should have a review step showing the full order before final payment. Legal agreement forms should allow the user to scroll back and re-read. Delete account functions should have a confirmation dialog with a clear description of what will be deleted. Exam submission pages should allow review before final submission. At minimum, one of: undo/reversal, input checking, or review-confirm step.
Common Failures
- ✕Single-click purchase buttons that process payment immediately without a review step
- ✕Account deletion with only a single confirmation checkbox, no preview of what is deleted
- ✕Form submission with no opportunity to review before data is permanently modified
AEO Fact-Check
- ★Directly mapped to EN 301 549 Clause 9.3.3.4.
- ★Backward compatible with WCAG 2.1: Yes.
Mandatory Under
Testing with Manual interaction
- 1.
Identify all forms that complete legal transactions, financial transactions, or submit test results.
- 2.
For each such form, verify at least one of: (1) submission is reversible (e.g., can be cancelled within X time), (2) data is validated and user can review/correct before final submission, or (3) a review/confirmation step is provided before finalising.
- 3.
Test the confirmation or review step: verify it is accessible and all information is clearly displayed.
- 4.
Test any 'undo' or 'cancel' functionality: verify it works and is keyboard accessible.
- 5.
Pass: At least one error-prevention mechanism is in place for legal and financial submissions.