WCAG reference

What Each Version of WCAG Added

Standards move. Laws mostly do not. That gap is why the version a rule arrived in still decides whether it applies to you.

WCAG 2.2 holds 86 success criteria, and 55 of them sit at Level A or AA, which is the set an audit tests. They did not arrive together. WCAG 2.0 published 61 criteria in 2008. WCAG 2.1 added 17 to that in 2018. WCAG 2.2 added 9 more in 2023 and withdrew one, which is the only time the standard has ever taken a rule away, and it is why 60 of the 2008 criteria are still in force rather than 61.

That history would be trivia if legislation kept pace with it. It does not. Of the 38 laws we cover, 9 still name WCAG 2.0 and 23 name 2.1, so a rule written in 2022 can sit outside what your regulator asks for and still be the thing stopping somebody paying you. Our guide to versions and levels covers how to choose which one to target. And if you already hold a report written against an older version, moving a 2.1 audit to 2.2 covers what testing only the new rules leaves unanswered, including the four definitions that changed underneath ten of the criteria you already had results for.

From 2.0: 60
From 2.1: 17
From 2.2: 9
Removed: 1

WCAG 2.0 (2008)

The foundation, published on 11 December 2008 and never updated since. Sixty of the criteria still in force were written here, and they carry most of the weight in an audit today.

60 criteria, still in force today

WCAG 2.1 (2018)

Ten years later, for a web that had moved to phones. W3C wrote it to address three groups, which were mobile users, people with low vision, and people with cognitive and learning disabilities.

17 criteria added

WCAG 2.2 (2023)

More of the same three groups, and a hard look at what goes wrong at sign-in. It also withdrew a criterion, which had never happened before and has not happened since.

9 criteria added

The One Criterion WCAG 2.2 Removed

4.1.1 Parsing asked that markup carry complete tags, correct nesting, no duplicate attributes and unique IDs. It was written when assistive technology read your HTML for itself, and back then a stray tag could genuinely break a page.

Assistive technology does not read your HTML anymore. A screen reader takes the tree the browser has already built, so the browser’s own recovery is the only parsing that happens and the rule had nothing left to protect. W3C has since gone further than removing it. WCAG 2.1 now carries a Note saying the criterion should be considered always satisfied for any content using HTML or XML, and the same wording sits on the WCAG 2.0 errata page. Against the current text of either version, there is nothing left to prove.

That is not quite the end of it, because some regulations name a dated version rather than the current one. The DOJ’s Title II rule incorporates WCAG 2.1 as published on 5 June 2018, and that text predates the Note. Our guide to what happened to 4.1.1 Parsing works through all four positions W3C holds at once, and where a duplicate ID finding belongs now.

The short version is that duplicate IDs are still worth fixing. One can send a label to the wrong control, and that breaks 4.1.2 Name, Role, Value, which is a live rule at Level A.

Each Version Gets Republished Too

A version number is not a fixed document, and this is the part that catches people out. WCAG 2.0 came out on 11 December 2008 and has never been republished, so its corrections live on a separate errata page. WCAG 2.1 came out on 5 June 2018 and has been republished three times since, on 21 September 2023, 12 December 2024 and 6 May 2025. WCAG 2.2 came out on 5 October 2023 and was republished on 12 December 2024, which changed four defined terms and no criteria.

A standard at a dated address never changes. So a law that names one has frozen that text on the day it named it, and every correction W3C has published since then sits outside the regulation. That is the whole mechanism behind the 4.1.1 answer above, and it is why two people can both be right about the same criterion while working to different documents.

WCAG 2.2 Is Also ISO/IEC 40500:2025

WCAG 2.2 was approved as an international standard on 21 October 2025 and published as ISO/IEC 40500:2025, free to download from ISO. That matters for anyone reading a national law, because a country adopting an international standard cites the ISO number rather than a W3C address. So ISO/IEC 40500 is the name WCAG 2.2 is most likely to appear under in the next wave of legislation. WCAG 2.0 went the same route and is ISO/IEC 40500:2012.

One detail is worth taking into a procurement conversation. The ISO edition is the October 2023 text of WCAG 2.2 rather than the December 2024 republication, so it sits one correction behind the W3C edition. W3C expects that December 2024 version to appear as ISO/IEC 40500:2026 by late 2026.

The 2025 edition also cancels and replaces ISO/IEC 40500:2012, which is the part that changes what an old document means. Before October 2025 the bare number pointed at WCAG 2.0 and there was nothing else it could point at. It now points at WCAG 2.2, so the same four digits name two different standards, and a different number of criteria, depending on when the document quoting them was written.

If a tender asks for ISO/IEC 40500 and gives no year

Do not read an edition into it, because the two editions ask for different work and the ISO update did not amend anybody’s contract on its own. Ask which one the requirement means, and set out what each answers.

ISO/IEC 40500:2012. WCAG 2.0. That is 38 criteria at Levels A and AA, and its list still carries 4.1.1 Parsing.
ISO/IEC 40500:2025. WCAG 2.2, in its October 2023 text. That is 55 criteria at A and AA, without the December 2024 corrections.
A citation with no year. Unresolved until the buyer says. A contract signed while the bare number meant WCAG 2.0 keeps meaning WCAG 2.0 until the parties change it.

Where the buyer has no view, testing against WCAG 2.2 answers both editions on the standard’s own backwards-compatibility statement, with the 4.1.1 question above as the one thing to check separately. Say in writing which edition you tested against, since that is the sentence the next reader of the file will need.

Which Version Your Audit Should Target

We test against WCAG 2.2 at Levels A and AA, which is 55 success criteria. W3C states that content conforming to WCAG 2.2 also conforms to WCAG 2.1 and to WCAG 2.0, so testing the newest version covers the older ones on the standard's own terms. What that sentence cannot settle is your regulator. A law names a version, and a regulator is free to keep a criterion the newer version dropped, which is why the answer to “does a 2.2 audit discharge my 2.0 duty” is a question about the instrument that binds you rather than about WCAG.

If your regulator names an older version and you need the conformance claim written against that one, say so when you order and the report will be framed that way. Which law applies to you is covered on the laws index.

Not sure which version applies to you?

We test against WCAG 2.2 at A and AA, and the report says which of your findings would also fail an older version. That is usually the fastest way to answer a regulator, and it is the fastest way to stop arguing about which document you are working to.

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