Understandable · Level AAA · Introduced in WCAG 2.0
WCAG 3.3.6: Error Prevention (All)
Published by whatisADA / Grow Wild Agency · Updated
What this criterion means
At Level AAA, all pages requiring information submission provide reversal, checking with correction, or review/confirmation with correction. This extends error-prevention protection beyond the consequential categories in 3.3.4.
A practical example
A feedback form lets someone review the selected category and message before sending, with an Edit action that returns to the completed fields. The final step does not silently change the submitted values.
How to check it
- Inventory every information-submission flow, including simple feedback and preferences.
- Verify a permitted prevention route for each flow.
- Make and correct an intentional mistake, then confirm the final submitted values reflect the correction.
What can be missed
Do not assume that a protection added to checkout also covers unrelated forms. This AAA criterion has broader scope than the AA requirement.
Record your test
Use this worksheet to record what you actually checked. Notes stay on this device when you choose Save; they are not sent to us. Avoid personal or confidential information on shared devices.
These are your observations, not automated results or a conformance certificate. A complete evaluation needs appropriate scope, supported technologies, all applicable criteria and relevant page states.
Primary sources and scope
This is independent implementation guidance with original examples. The linked standard contains the full definitions, exceptions and conformance requirements. A criterion or checklist alone does not establish legal applicability or whole-site conformance.