WCAG

WCAG is the Web Content Accessibility Guidelines, published by the W3C. It matters because almost every accessibility law and procurement requirement in the world points at it rather than writing its own rules.

The structure, which the vocabulary obscures

Four principles — perceivable, operable, understandable, robust. POUR.

Thirteen guidelines sit under those principles in WCAG 2.2.

Testable success criteria sit under the guidelines, and these are the only things conformance is measured against. A claim to "follow the principles" is not a conformance claim.

Each success criterion carries a level: A, AA or AAA.

Level AA is the answer

Laws and contracts almost always specify AA. It is the level to plan against, budget for, and claim.

AAA is not meant to be applied to a whole product, and the W3C says as much. A contract committing to AAA across a product is usually a sign that nobody involved read the standard, and it is worth flagging before signing rather than after.

Versions, and the trap in them

Each version adds to the previous one. Anything conforming to 2.2 also conforms to 2.1, so the versions are not alternatives.

⚠️ The trap is which version your obligation names. EN 301 549, the European standard used for the European Accessibility Act, currently references WCAG 2.1. A European contract may therefore not be asking for 2.2 at all, and building to 2.2 is a choice rather than a requirement. WCAG 2.2 is also ISO/IEC 40500:2025, which is the form some procurement documents ask for.

Check which version the obligation names before scoping the work. The difference is real money.

What it actually asks for

The criteria most B2B products fail are unglamorous and cheap to fix early.

Contrast. 4.5:1 for body text, 3:1 for large text, and 3:1 for interface components and their states. See color system, and note that the ratio is measured against the background the element actually sits on rather than against white.

Keyboard access. Everything operable by mouse must be operable by keyboard, with a visible focus indicator. This is where a div with a click handler fails, and where most custom dropdowns and modals fail.

Names, roles and values. Assistive technology has to be able to announce what a control is and what state it is in. A styled div acting as a checkbox announces nothing.

Not colour alone. A state signalled only by colour fails, which is why an error needs an icon or text beside the red.

Target size. WCAG 2.2 added a 24 by 24 CSS pixel minimum at AA, with exemptions including links inline in text.

Where teams get it wrong

• Treating it as a launch checklist. Retrofitting conformance costs several times what building to it does.
• Claiming AAA. A commitment nobody can hold across a product.
• Testing with a scanner only. Automated tools catch a minority of criteria. The rest need a person.
• Building to 2.2 when the contract names 2.1, or the reverse, without checking.
• Contrast checked against white rather than the real background.
• Principles quoted in place of criteria. Conformance is measured one way only.