Success Criteria

WCAG 3.3.3 Error Suggestion

Success Criterion 3.3.3 requires that if an input error is automatically detected and suggestions for correction are known, those suggestions are provided to the user, unless doing so would jeopardize security or the content's purpose. It's a Level AA criterion under Guideline 3.3 (Input Assistance) — a step beyond 3.3.1 Error Identification, which only requires identifying that there's a problem.

The distinction from Error Identification

3.3.1 requires saying what is wrong and where. This criterion requires going further, when practical: saying how to fix it. "Invalid date" identifies an error; "Please enter the date as MM/DD/YYYY" suggests the fix.

Where suggestions are genuinely knowable

• Format errors — a date, phone number, or postal code in the wrong format: state the expected format explicitly
• Required fields left blank — "This field is required" is itself the suggestion
• Value out of range — "Enter a number between 1 and 100" tells the user exactly what's expected
• Spelling-adjacent mismatches — some systems can suggest "did you mean...?" for likely typos in structured fields

The security exception

Suggestions aren't required where providing them would compromise security or the content's purpose — the standard example is a login form's "incorrect password" message. Specifying exactly why a password was rejected (too short, wrong character, etc.) could help an attacker narrow down valid credentials through trial and error, which is why login and similarly sensitive forms are explicitly exempted from needing detailed correction suggestions.

Practical guidance

Wherever a validation rule is specific and known in advance (a required format, a range, a required field), surface that exact expectation in the error message rather than a generic "invalid input" — this is usually a wording change to existing validation logic, not new functionality, making it one of the more cheaply satisfiable AA-level criteria once basic error identification (3.3.1) is already in place.

Common questions

What is WCAG 3.3.3?

A Level AA criterion: when an input error is detected and you know how to fix it, tell the user the suggested correction in text.

What is an example?

Instead of just 'Invalid date,' say 'Enter the date as MM/DD/YYYY.' For a missing required field, name it and say it is required.

When is a suggestion not required?

When suggesting a correction would compromise security or the purpose of the content, or when the correct value genuinely isn't known.