A clean automated scan does not mean your website conforms to WCAG. Scans only flag approximately 25% of accessibility issues. The other 75% require human evaluation. A scan returning zero issues means the tool did not detect anything within its narrow detection range. It does not mean your site is accessible or that it meets any legal standard.
This is one of the most common misunderstandings in digital accessibility. Organizations receive a clean scan report, assume they are in good shape, and move on. Months later, they receive a demand letter or a complaint from a user who cannot navigate their site with a screen reader. The scan never evaluated screen reader functionality. It was never designed to.
| 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.
Why Do So Many Sites Pass Scans but Still Have Issues?
Most accessibility issues are contextual. They depend on how content is structured, how interactive components behave, and how assistive technology interprets the experience. These are things code-level pattern matching cannot assess.
A page could have every image tagged with alt text and still be inaccessible because the alt text is meaningless. A form could have labels on every field and still be unusable because the error handling does not communicate what went wrong. A navigation menu could pass every automated check and still be impossible to operate without a mouse.
Scans and audits are completely separate activities. A scan checks code patterns. An audit evaluates the full user experience against WCAG criteria, including keyboard operability, screen reader interaction, content structure, and more.
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 Clean Scan Reduce Legal Risk?
Not meaningfully. ADA compliance obligations and state-level accessibility laws like Colorado’s HB21-1110 reference WCAG conformance as the technical standard. A scan result showing zero detected issues does not demonstrate conformance. Courts and regulators look at whether the site is actually accessible to people with disabilities, not whether a tool returned a passing score.
Organizations that rely on scan results alone often discover this when it is too late. A demand letter arrives, and the clean scan report does not provide a credible defense because it never evaluated the issues the complainant experienced.
The document that carries weight is an Accessibility Conformance Report (ACR), which maps your product or site against WCAG criteria based on a real evaluation. An ACR is produced from audit findings, not scan output.
Can You Use Scan Results Alongside an Audit?
Scans are useful as a preliminary check and as an ongoing monitoring layer after remediation. They catch regressions in code-level issues quickly. But they are a separate activity from an audit and do not contribute to conformance determination.
Think of it this way: a scan is a spell checker. An audit is an editor. The spell checker catches typos, but it cannot tell you whether your argument makes sense. Both have a role, and neither replaces the other.
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.
