Category: WCAG Principles and Conformance

Error Suggestion

Also known as: WCAG Success Criterion 3.3.3, SC 3.3.3

Simply put

Error Suggestion is a web accessibility requirement that when a form or input field detects a mistake, and the system knows how to fix it, the website should tell the user what to do to correct it. For example, if someone enters an invalid date, the form might suggest the correct format rather than just saying the entry is wrong. This helps people, especially those using assistive technology, understand and fix their errors more easily.

Formal definition

Error Suggestion is WCAG Success Criterion 3.3.3, a Level AA criterion first introduced in WCAG 2.0 and carried forward through WCAG 2.1 and 2.2. It states that if an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless doing so would jeopardize the security or purpose of the content. The criterion applies only when an error is programmatically detected and a correction is known; it does not require the detection of all possible errors, and it is distinct from SC 3.3.1 (Error Identification), which addresses identifying and describing that an error occurred. As a WCAG conformance criterion, meeting it is one component of accessibility and does not by itself guarantee an accessible experience or legal compliance; manual and assistive technology testing are generally required.

Why it matters

Forms are among the most common points of interaction on the web, and they are also frequent sources of frustration when errors occur. When a system detects that a user has entered invalid data but only communicates that something is wrong, users are left to guess what the correct input should be. For people using assistive technologies, those with cognitive disabilities, or anyone under time pressure, this ambiguity can turn a simple task into an insurmountable barrier. Error Suggestion (WCAG Success Criterion 3.3.3) addresses this gap by requiring that, when an input error is automatically detected and a correction is known, the system provides that suggested correction to the user.

The value of this criterion lies in reducing the guesswork involved in recovering from mistakes. A message that says an entry is invalid does far less to help a user than one that explains the expected format or offers a concrete correction. This matters especially in high-stakes contexts such as account registration, payment, appointment scheduling, or government service applications, where an unresolved form error may mean a user cannot complete an essential task at all.

As a Level AA criterion, Error Suggestion is commonly included among conformance targets, but meeting it is only one component of an accessible form experience. Satisfying this success criterion does not by itself guarantee that a form is usable for all people, nor does it ensure legal compliance. Manual testing and testing with assistive technologies are generally required to confirm that suggestions are actually perceivable and helpful in practice, and organizations should treat this criterion as part of a broader accessibility effort rather than a standalone fix.

Who it's relevant to

UX and Interface Designers

Designers shape how form errors are communicated. Applying Error Suggestion means designing error messages that explain expected formats or offer concrete corrections rather than simply flagging an entry as invalid, while accounting for the security exception where revealing correction details would be inappropriate.

Front-End and Accessibility Engineers

Developers implement the validation logic and the mechanisms that surface suggested corrections to users, including through assistive technologies. Because automated checks detect only a portion of issues, engineers should verify with manual and assistive technology testing that suggestions are programmatically available and perceivable when an error is detected.

Compliance Officers and Accessibility Leads

Those tracking WCAG conformance should recognize Error Suggestion as a Level AA criterion carried forward from WCAG 2.0 through 2.1 and 2.2, and commonly included in AA conformance targets. Meeting it is one component of accessibility and does not by itself guarantee an accessible experience or legal compliance.

Legal Counsel and Business Leaders

WCAG success criteria such as Error Suggestion are often cited as benchmarks in accessibility contexts, but conformance with a single criterion does not ensure legal safety. This entry is not legal advice; requirements evolve through regulation and case law, and organizations should consult qualified legal counsel and monitor current agency guidance for their specific jurisdiction.

Content and Form Authors

People who write field labels, help text, and error messages contribute directly to whether users can recover from mistakes. Clear, actionable correction guidance for detected errors supports the intent of this criterion and improves the experience for users with cognitive and other disabilities.

Inside Error Suggestion

Success Criterion 3.3.3 (Error Suggestion)

A WCAG success criterion at Level AA, introduced in WCAG 2.0, which provides that when an input error is automatically detected and suggestions for correction are known, those suggestions are provided to the user, unless doing so would jeopardize the security or purpose of the content.

Automatically detected input error

An error that the system can identify programmatically, such as a required field left blank, data entered in an unexpected format, or a value outside an accepted range. The criterion applies when such detection occurs.

Known correction suggestions

Guidance offered to the user on how to fix the detected error, for example indicating the expected date format, listing acceptable values, or suggesting a corrected entry. The criterion applies when a suggestion is known to the system.

Security and purpose exception

The criterion does not require suggestions where providing them would jeopardize the security or defeat the purpose of the content, such as revealing part of a password or the correct answer to a security question.

Relationship to other error-handling criteria

Error Suggestion works alongside related criteria such as Error Identification (3.3.1) and, at Level AA, Error Prevention for legal, financial, and data contexts (3.3.4), each addressing distinct aspects of how errors are surfaced and handled.

Common questions

Answers to the questions practitioners most commonly ask about Error Suggestion.

Does meeting the Error Suggestion criterion mean my form is fully accessible?

No. Error Suggestion (WCAG 2.0 Success Criterion 3.3.3, Level AA) addresses only one aspect of error handling, providing suggestions for correcting detected input errors when suggestions are known and doing so would not jeopardize security or purpose. It works alongside related criteria such as Error Identification (3.3.1) and Labels or Instructions (3.3.2). Satisfying it does not guarantee an accessible form overall, nor does it guarantee an accessible experience for all users. Automated testing detects only a portion of potential issues, so manual review and testing with assistive technology are generally needed.

Is Error Suggestion legally required under the ADA?

The ADA is a US civil rights law and does not itself contain detailed web technical specifications, so it does not name individual WCAG success criteria such as Error Suggestion. WCAG is a set of technical guidelines published by the W3C through the Web Accessibility Initiative, and its criteria are often cited as a benchmark in settlements, regulations, and agency guidance rather than codified directly into the ADA. Whether conformance with this criterion is expected in a given context depends on the applicable authority and current rulemaking or case law. This is not legal advice; consult qualified legal counsel for your situation.

When does the Error Suggestion criterion actually apply?

It applies when an input error is automatically detected and suggestions for correction are known. In those cases, the suggestions should generally be provided to the user, unless doing so would jeopardize the security or purpose of the content. If no suggestion can be reasonably determined, the criterion does not require inventing one; providing a clear description of the error may still be appropriate under related criteria.

How should error suggestions be presented so assistive technology users can access them?

Suggestions should be conveyed in text so they are programmatically available, not communicated by color or visual position alone. Associating error messages with the relevant field and ensuring they are announced to screen reader users are common approaches. Because presentation techniques vary by platform and framework, manual testing with assistive technology is generally recommended to confirm the suggestion is perceivable and understandable in context.

What is the difference between Error Identification and Error Suggestion?

Error Identification (Success Criterion 3.3.1, Level A) concerns detecting an input error and describing it to the user in text. Error Suggestion (Success Criterion 3.3.3, Level AA) goes further by providing guidance on how to correct the error when a suggestion is known and providing it would not compromise security or purpose. They are distinct criteria at different conformance levels and are often addressed together in form design.

How can teams test whether error suggestions meet this criterion?

Testing commonly involves submitting forms with a range of invalid inputs to confirm that, where the correct value can be reasonably suggested, a helpful suggestion is presented in text. Reviewers may verify the suggestion is associated with the correct field and available to assistive technology. Because automated tools detect only a portion of issues, this criterion generally benefits from manual evaluation and testing with assistive technology rather than automated checks alone.

Common misconceptions

Error Suggestion requires that every error include a correction suggestion.

The criterion applies only when an input error is automatically detected and a correction suggestion is known. It also includes an exception where providing suggestions would jeopardize security or the purpose of the content, so a suggestion is not always mandated.

Simply marking a field as invalid satisfies Error Suggestion.

Indicating that an error exists relates more to Error Identification (3.3.1). Error Suggestion generally goes further by providing guidance on how to correct the error when such guidance is known.

Meeting Error Suggestion means a form is fully accessible and legally compliant.

Conformance with a single success criterion does not guarantee an accessible experience or legal compliance. WCAG conformance is one component; manual and assistive technology testing are needed, and legal obligations depend on the applicable authority and evolving case law and regulation. This is not legal advice.

Best practices

When an input error is automatically detected and a correction is known, present a specific, actionable suggestion in text rather than relying solely on color or a generic message.

Programmatically associate error messages and suggestions with their corresponding fields so that assistive technologies convey them to users, and verify this with screen reader testing.

Communicate expected formats and constraints proactively (for example, date format or acceptable value ranges) to reduce errors before submission.

Apply the security and purpose exception judiciously, withholding suggestions only where providing them would compromise security or defeat the content's purpose, such as with passwords or security answers.

Coordinate Error Suggestion with related criteria such as Error Identification (3.3.1) and, where applicable, Error Prevention (3.3.4), rather than treating error handling as a single control.

Validate error-handling behavior through manual and assistive technology testing, since automated tools detect only a portion of issues and cannot confirm the usefulness of suggestions.