A clean automated scan showing zero errors does not mean your website is WCAG conformant or ADA compliant. Scans only flag approximately 25% of accessibility issues. A scan returning zero issues means the tool did not detect anything within its narrow detection range.
This is one of the most common misunderstandings in web accessibility. Organizations receive a clean scan report, assume they are in good shape, and move on. However, their website isn’t WCAG 2.1 AA or WCAG 2.2 AA conformant and risk for web accessibility litigation is still resent.
| Assumption | Reality |
|---|---|
| No issues exist | The scan did not detect issues within the approximately 25% of criteria it can evaluate |
| Site conforms to WCAG | Scans cannot determine WCAG conformance at any level |
| Legal risk is addressed | A clean scan carries no legal weight as evidence of conformance |
| No further action needed | A (manual) accessibility audit is the only way to determine WCAG conformance |
What Does a Clean Scan Actually Mean?
Automated scans check code against a set of programmatic rules. They can identify things like missing alt attributes on images, empty form labels, or low color contrast ratios. These are real issues worth catching.
But scans cannot evaluate whether an alt attribute accurately describes the image it is attached to. They cannot determine whether a custom dropdown menu is operable with a keyboard. They cannot assess whether a modal dialog traps focus correctly or whether a screen reader announces dynamic content updates in a logical order.
A clean scan means the tool’s rules did not trigger. It says nothing about the 75% of WCAG criteria that require human judgment to evaluate.
What Should You Do After a Clean Scan?
A clean scan is a starting point, not a finish line. The next step is a (manual) accessibility audit conducted by a qualified evaluator. This is the only way to determine whether your site actually conforms to WCAG 2.1 AA or WCAG 2.2 AA.
An accessibility audit evaluates every applicable WCAG criterion across a representative sample of pages and components. It identifies issues that scans cannot detect: interaction patterns, content relationships, assistive technology compatibility, and cognitive accessibility considerations.
Accessible.org audits are fully (manual) and evaluate against the full scope of WCAG criteria. The audit report identifies each issue, maps it to the relevant success criterion, and provides remediation guidance developers can act on.
Does a Scan Showing Zero Issues Reduce Legal Risk?
Yes, having zero errors on a scan is always a great start and does reduce your risk, but there is more work to be done.
Is a clean automated scan enough for ADA compliance?
No. ADA compliance requires WCAG conformance, and scans only flag approximately 25% of issues. A (manual) accessibility audit is the only way to determine conformance. A clean scan does not serve as evidence of accessibility in legal proceedings.
How soon after a clean scan should we get an audit?
As soon as practical. A clean scan does not change your risk profile or conformance status. The sooner an audit identifies the issues scans cannot detect, the sooner your team can begin remediation and move toward actual WCAG conformance.
What percentage of accessibility issues can scans detect?
Scans flag approximately 25% of accessibility issues. The remaining 75% require human evaluation against WCAG criteria, including keyboard operability, screen reader compatibility, content structure, and interaction design.
A clean scan report feels reassuring, but it reflects a narrow view of accessibility. The issues it cannot detect are often the ones that matter most to real users navigating your site with assistive technology. The path from a clean scan to actual conformance runs through a (manual) audit.
Contact Accessible.org to schedule an accessibility audit and determine where your site actually stands.
