Web accessibility is the quality that keeps a website or digital service usable by people who browse with assistive technology or without a mouse and screen: screen readers, keyboard only, text magnification, voice control, braille displays.
The first thing to settle is not the conformance level to aim for. It is which of the legal duties applies to you, because in the UK there are three, with different audiences and different requirements, and they are often mixed together into a single discussion.
Three different obligations, not one
The first is the Equality Act 2010 (the Disability Discrimination Act 1995 in Northern Ireland). It is not a website law and sets no technical standard, but it applies to every service provider regardless of size: as the government guidance puts it, "all UK service providers have a legal obligation to make reasonable adjustments". For a business that sells or takes bookings online, the website is part of the service.
The second is the Public Sector Bodies (Websites and Mobile Applications) (No. 2) Accessibility Regulations 2018, in force since 23 September 2018. It covers public sector bodies only and is specific: meet WCAG 2.2 at level AA and publish an accessibility statement on the site, explaining what is not yet accessible and why, and review it regularly. The Government Digital Service monitors a sample of sites every year; enforcement is by the Equality and Human Rights Commission in Great Britain and the Equality Commission for Northern Ireland.
The third is the European Accessibility Act, Directive (EU) 2019/882. It is not UK law, but it applies to services offered to consumers in the EU, so it concerns UK businesses that sell into the EU. Here the test is not turnover but sector: it applies to consumer services placed on the market from 28 June 2025, PDF documents included. Microenterprises providing services are exempt, but the definition has two parts: fewer than 10 employees and annual turnover or balance sheet total not above 2 million euros. A company with 6 employees and a turnover and balance sheet of 3 million euros each is in scope.
The technical reference for the EAA is the harmonised standard EN 301 549, which in turn points to WCAG. So the three obligations end up measured against the same guidelines, even though they apply to different organisations.
| Reference | Who it covers | Since | Requirement | Enforcement |
|---|---|---|---|---|
| Equality Act 2010 (DDA 1995 in Northern Ireland) | All service providers, any size | In force | Reasonable adjustments, anticipating the needs of disabled users; no set technical standard | EHRC, ECNI and individual claims |
| Public Sector Bodies Accessibility Regulations 2018 | Public sector websites and apps | 23 September 2018 | WCAG 2.2 AA and an accessibility statement, reviewed regularly | Monitoring by GDS, enforcement by EHRC and ECNI |
| European Accessibility Act (Directive 2019/882) | Consumer e-commerce, banking services, passenger transport, electronic communications, access to audiovisual media, e-books and related software, when offered in the EU | 28 June 2025 | Accessibility information as set out in Annex V, plus conformity with the requirements | National authorities in each EU country where the service is offered |
| Microenterprises | Fewer than 10 employees and turnover or balance sheet not above 2 million euros | n/a | Exempt from the EAA service obligations, not from the Equality Act | n/a |
On penalties, the Equality Act has no fixed fine for an inaccessible website: the risk is enforcement action by the commissions and claims by users. Under the EAA, penalties are set by each member state, so the figure depends on where the service is sold. Fixed amounts that circulate in blog posts vary from source to source and we don't repeat them here.
Perceivable, operable, understandable, robust
The technical standard is the W3C's Web Content Accessibility Guidelines. The current version is WCAG 2.2, a W3C Recommendation since 5 October 2023 and updated on 12 December 2024: 13 guidelines, 9 success criteria new compared with 2.1, and three conformance levels, A, AA and AAA. The level the UK public sector regulations and the European rules use as the working threshold is AA.
The four principles translate into things that live in the markup. Perceivable: alternative text on images, captions on videos, sufficient contrast. Operable: everything reachable by keyboard, no focus traps, no imposed time limits. Understandable: declared language, clear labels on forms, predictable behaviour. Robust: semantic HTML and ARIA attributes used correctly, so that assistive technology can interpret the page without guessing.
Three of the four principles run through elements anyone working on the site already knows: alt text, the hierarchy of heading tags, breadcrumbs.
Six errors make up 96% of the problem
The largest survey available is The WebAIM Million, which in February 2026 analysed the markup of one million home pages. It is an international sample and should be read as such. 95.9% of home pages had automatically detectable WCAG errors, worse than 94.8% in 2025. The average is 56.1 errors per page, 10.1% more than the year before.
| Error detected | Home pages affected |
|---|---|
| Low contrast text | 83.9% |
| Missing alternative text on images | 53.1% |
| Missing form input labels | 51.0% |
| Empty links | 46.3% |
| Empty buttons | 30.6% |
| Missing document language | 13.5% |
96% of all errors detected fall into these six categories. None needs a redesign: they are fixes to the code and the colour palette, and on a medium-sized site they are closed in a few days of work. It is the part of the problem worth tackling before any discussion of formal conformance.
How to test it, and what the tools don't see
Lighthouse accessibility audits are based on Deque's axe-core. The Chrome documentation explains how the score works: it is a weighted average of pass/fail audits, with no partial scores, and manual audits are not included in the calculation. A 100 in Lighthouse says no automated errors were found, not that the site conforms.
What the tools don't see has to be tested by hand, and it takes less time than it seems: go through a whole page with the Tab key alone, checking that focus is always visible and the order makes sense; zoom to 200% and see whether the content reflows; open a contact form with a screen reader. In the WebAIM survey of 1,539 screen reader users (December 2023 to January 2024) the most common primary screen readers were JAWS at 40.5%, NVDA at 37.7% and VoiceOver at 9.7%. Take these proportions as a guide to which software is worth installing for testing, not as a picture of any one country's users.
Overlay widgets deserve a note, because they are sold as a way to comply. They sit on top of the page and don't touch the markup: the errors in the table above stay where they are, and so does any breach.
Where it overlaps with SEO work
Accessibility is not a ranking factor, and anyone selling it as a shortcut to rankings is selling something else. The overlap is that the work lands on the same things: heading structure, alternative text, semantic markup, navigability. They are the same elements technical SEO works on, and markup that a screen reader interprets without guessing is also markup a crawler interprets without guessing. It is worth rereading how search engines work with this overlap in mind.
One area where the two jobs almost entirely coincide is performance measured in the field: the Core Web Vitals thresholds reward the same choices that make a page usable on a slow connection or an old device. Otherwise accessibility is a component of user experience with its own legal framework, and that is where it belongs. If you are deciding where to fit it into a wider work plan, our SEO services start with a technical audit that catches many of these errors.
The obligation is on the service, not the site
One point is often passed over. The European Accessibility Act does not regulate websites, it regulates services: an accessible checkout that emails a scanned PDF invoice at the end of the order leaves the service non-compliant, because the part the consumer has to read can't be read. The same goes for e-tickets, booking confirmations and bank statements. The directive also contains a duty few people mention: when a service does not comply, the provider must take corrective action and inform the competent national authorities of the member states where the service is offered. For a UK business selling into several EU countries, a conformance claim made once and then left alone is a different risk from before.
Frequently asked questions about web accessibility
WCAG calls them perceivable, operable, understandable and robust. In practice: content must reach people who can't see or hear it, the interface must work without a mouse, language and behaviour must be predictable, and the code must be interpretable by assistive technology without ambiguity.
When it meets the WCAG success criteria at the declared level, normally level AA. Testing is not only automated: tools such as Lighthouse cover errors detectable in the markup, while tab order, focus visibility and how understandable a form is have to be tested by hand.
It depends on the service, not the size of the site. The European Accessibility Act applies to e-commerce, consumer banking, passenger transport, electronic communications, audiovisual media and e-books offered in the EU, and microenterprises with fewer than 10 employees and no more than 2 million euros in turnover or balance sheet are exempt. The Equality Act duty to make reasonable adjustments, however, applies to UK service providers of any size.
No. Overlays sit on top of the page without fixing the underlying markup, so low contrast, missing alt text and missing form labels stay where they are. Compliance comes from changes to the code and the design.
