WCAG

The WCAG are organized into three levels. At the top are four principles: content must be perceivable, operable, understandable and robust. Thirteen guidelines are assigned to these principles, describing the goals. According to the W3C, the guidelines themselves are not testable.

The bottom level consists of the success criteria. They are the testable part of the standard, and conformance is decided by them alone. WCAG 2.2 contains 86 success criteria, of which 31 are at level A, 24 at level AA and 31 at level AAA. WCAG 2.1 contains 78 success criteria, of which 30 are at level A, 20 at level AA and 28 at level AAA.

Alongside the standard itself, the W3C publishes supporting documents, including "Understanding WCAG 2" and "Techniques for WCAG 2". They explain the success criteria and show ways to implement them, but they are not the standard.

WCAG 2.0 was published on 11 December 2008. WCAG 2.1 was published on 5 June 2018, with updated editions released on 21 September 2023, 12 December 2024 and 6 May 2025. WCAG 2.2 was published on 5 October 2023, with an updated edition on 12 December 2024. This 12 December 2024 edition is the current W3C Recommendation.

All three versions remain in effect side by side. WCAG 2.2 does not supersede WCAG 2.1, and WCAG 2.1 does not supersede WCAG 2.0. Later versions add success criteria and do not change existing ones. The one exception is success criterion 4.1.1 Parsing, which is considered obsolete in WCAG 2.2 and has been removed.

The versions are backward compatible. Content that meets WCAG 2.2 also meets WCAG 2.1 and WCAG 2.0. WCAG 2.2 is also published as the international standard ISO/IEC 40500:2025.

Neither the BFSG (German accessibility law) nor the BITV 2.0 names the WCAG. Both work with a presumption of conformity: anyone who complies with harmonized standards whose references have been published in the Official Journal of the European Union is presumed to meet the legal requirements. For the private sector this is set out in § 4 BFSG, and for federal public bodies in § 3 paragraph 2 BITV 2.0.

The standard named in the Official Journal for public bodies is EN 301 549. Its version V3.2.1 (2021-03) was named as a harmonized standard for websites and mobile applications in the Official Journal by Commission Implementing Decision (EU) 2021/1339 of 11 August 2021, there with reference to Directive (EU) 2016/2102. This edition adopts the success criteria of WCAG 2.1 at levels A and AA; it lists the level AAA criteria only for information.

The Bundesfachstelle für Barrierefreiheit (Federal Accessibility Office) describes EN 301 549 as "currently the central technical reference for implementing accessibility requirements in the digital domain" and names WCAG 2.1 as the edition referenced within it, noting that an updated edition of the standard will reference WCAG 2.2. The W3C describes the same state of affairs: EN 301 549 currently uses WCAG 2.1, and the next edition is expected to use WCAG 2.2.

How the WCAG can be implemented in practice is described on the topic page about the WCAG. Related fact pages: the fact page about the BFSG and the fact page about sitebrunch GmbH. All fact pages are listed on the facts overview.

The WCAG are not a law. Their criteria only become legally binding through national rules and the EN 301 549 standard.

The conformance level applied in law is AA, not AAA. EN 301 549 V3.2.1 adopts the success criteria of levels A and AA as requirements. The WCAG 2.2 themselves state in section 5.2.1 that AAA conformance should not be required as a general policy for entire websites, because it is not possible to satisfy all level AAA success criteria for some content.

A higher version number does not mean the previous version becomes invalid. WCAG 2.0, 2.1 and 2.2 are simultaneously valid standards.