3.3.3 Error Suggestion

1. What is the goal of this criterion?

Forms are like door locks – sometimes they open on the first try, sometimes they don’t. But what if the lock just says “Wrong!” instead of telling you what the right key looks like? People with cognitive disabilities, visual impairments or simply anyone under stress are left standing in front of a locked door.

The goal of WCAG Success Criterion 3.3.3 is clear: if a system detects an input error and knows how to fix it, it has to help. Not just “That’s wrong” – but “Here’s how to get it right”.

2. What exactly does it require?

Specifically, this criterion builds on Error Identification and takes it one decisive step further:

As soon as an input error is detected automatically and suggestions for correction are known, those suggestions must be shown.

That covers several scenarios:

Missing required information: instead of just “This field is required”, say “Please enter your email address, e.g. name@example.com”

Wrong formats: instead of “Invalid date”, say “Please use the format DD.MM.YYYY, e.g. 15.03.2026”

Disallowed values: instead of “Invalid input”, say “Please choose a month: January, February, March …”

Exception: the rule doesn’t apply if suggestions would jeopardise the security or purpose of the content – for example with passwords or security questions, or in a test where you’re supposed to find the right answer yourself.

3. Why does it matter for accessibility?

Imagine filling in an important form and getting nothing but cryptic messages like “Input invalid” for every mistake. Without concrete guidance, this can turn into an endless loop – or make you give up altogether.

Correction suggestions support accessibility because they:

• help people with learning difficulties complete forms successfully
• give blind and visually impaired people clearer guidance when fixing errors
• reduce the number of attempts for people with motor impairments
• support people with cognitive disabilities in understanding the expected input
• save everyone time and frustration by leading them straight to the goal

And last but not least: they make the web more human – nobody should have to guess what a system wants from them.

4. How to meet the criterion

The art lies not just in detecting errors but in offering helpful solutions. Here are the key tips:

Concrete suggestions instead of vague hints:

• Bad: “Invalid email format”
• Good: “The email address needs an @ sign, e.g. name@example.com”

Show examples of correct input:

• For date fields: “Please use the format DD.MM.YYYY, e.g. 24.12.2026”
• For phone numbers: “Please include the area code, e.g. 0951 123456”

Choices for limited values:

• Instead of just “Wrong month” → “Please choose: January, February, March, April …”
• Or concrete suggestions for typos: “Did you mean gmail.com instead of gmial.com?”

Technical implementation:

• Connect error messages and suggestions to the input with aria-describedby
• Place guidance directly next to the affected input field
• Validate in the browser for instant feedback – and validate on the server as well
• Show the same concrete suggestions for server-side errors too

Tools and techniques:

• Use pattern checks to spot common mistakes (e.g. mistyped domains) and suggest corrections
• Offer context-sensitive help right in the form
• Use autocomplete for common inputs (see Identify Input Purpose)
• Rely on proven form validation libraries

For orders, contracts or deleting data, Error Prevention (Legal, Financial, Data) also comes into play.

5. Why this criterion matters for businesses

Correction suggestions aren’t just a nice touch – they have a direct impact on your business success.

1. Fewer drop-offs

Every abandoned form is a lost order, sign-up or enquiry. Helpful error messages get more people to their goal because they don’t get stuck on a puzzle.

2. Lower support costs

Fewer confused people means fewer calls to customer support. When forms explain themselves, many problems solve themselves – saving time and money.

3. Better user experience

Frustrated customers don’t come back. Helpful suggestions build trust and say: “We’ll help you get where you want to go.” That strengthens customer loyalty and your brand image.

And then there’s the legal side: since 28 June 2025, the European Accessibility Act (Directive (EU) 2019/882) has applied to many consumer-facing digital services, such as online shops and banking services. Germany implements it through the Barrierefreiheitsstärkungsgesetz (BFSG). The technical benchmark is the harmonised standard EN 301 549, which refers to WCAG 2.1 Level AA for web content – and 3.3.3 is part of that. Public sector bodies are covered separately by the Web Accessibility Directive (EU) 2016/2102. This section is general information, not legal advice.

6. The success criterion in the W3C’s words

Success Criterion 3.3.3 Error Suggestion (Level AA)

If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content.

In short: if an input error is detected automatically and a fix is known, suggest it – unless that would compromise the security or purpose of the content.