Goal
Prevent serious consequences from user mistakes.
Success Criterion · WCAG 3.3.4
Error Prevention (Legal, Financial, Data)
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: submissions are reversible, data is checked for input errors and the user is provided an opportunity to correct them, or a mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.
Level AAWCAG 2.0Understandable3.3 · Input Assistance
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What to do
For legal/financial transactions or data changes, provide reversible, confirmable, or reviewable submissions.
Why it matters
Users can make errors; without safeguards, mistakes can cause significant harm or irreversible changes.
Success criterion
What WCAG 3.3.4 requires
Summarized directly from the official Understanding document so teams can quote the requirement accurately.
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: (1) Reversible. (2) Checked. (3) Confirmed.
Intent
Why WCAG created this requirement
- High-impact actions require additional protection against mistakes.
- Users should have a chance to review and correct before committing.
- Safeguards reduce harm and increase trust.
Benefits
Who gains when you pass
- Users with cognitive disabilities can avoid costly mistakes through review steps.
- Users using assistive tech reduce risk from navigation/focus errors.
- All users benefit from confirmation and undo patterns.
Why it matters
User impact when this criterion fails
Summaries drawn from the Understanding document help you socialize impact statements with product stakeholders.
Users may commit unintended purchases or delete data without recourse.
Users may submit incorrect information that cannot be corrected.
Overview
For high-stakes actions (financial, legal, data modification/deletion, test submission), provide at least one safeguard: allow reversing, validate/check for errors, or provide a confirmation/review step.
- Common patterns: review page, confirm dialog, undo toast, “Are you sure?” for destructive actions.
- Validation must be clear and actionable (see 3.3.1–3.3.3).
- At least one safeguard is required; multiple are better.
Reference: All summaries and highlights originate from Understanding WCAG 3.3.4 and the W3C quick reference.
Fast facts
- Conformance level
- Level AA
- WCAG version introduced
- WCAG 2.0
- Principle
- Understandable
- Guideline
- 3.3 · Input Assistance
Examples
Make success tangible for teams
Share pass/fail snapshots to coach designers, engineers, QA, and content authors.
Delete account
Pass
Requires confirmation and offers a final review of consequences.
Fail
Deletes immediately on click with no confirmation or undo.
Payment
Pass
Review page shows total and billing details before “Confirm purchase”.
Fail
Selecting a plan auto-charges immediately with no review.
Evidence to keep
Document conformance decisions
Capture artifacts for VPATs, procurement reviews, and regression testing.
- Document which flows are “high-stakes” and what safeguards are implemented.
- Capture evidence screenshots of review/confirm/undo UI.
Official resources
Deep dives and supporting material
Keep these links handy when writing acceptance criteria or responding to audits.
Implementation checklist
Capture progress and blockers
- Identify high-stakes actions (payments, account changes, deletions, test submissions).
- Add at least one safeguard: undo, review step, or confirmation.
- Ensure safeguards are accessible (keyboard, screen reader, focus management).
- Preserve user input through review and correction flows.
Testing ideas
Prove conformance with evidence
- Attempt high-stakes actions and verify undo/review/confirm exists.
- Trigger validation errors and confirm user can correct before commit.
- Test focus behavior in confirmation dialogs and review pages.
Related success criteria
More from Input Assistance (3.3)
WCAG 3.3.1Error IdentificationLevel AWCAG 3.3.2Labels or InstructionsLevel AWCAG 3.3.3Error SuggestionLevel AAWCAG 3.3.5HelpLevel AAAWCAG 3.3.6Error Prevention (All)Level AAAWCAG 3.3.7Redundant EntryLevel AWCAG 3.3.8Accessible Authentication (Minimum)Level AAWCAG 3.3.9Accessible Authentication (Enhanced)Level AAA