Category: Standards and Guidelines

ISO/IEC 40500

Also known as: ISO/IEC 40500:2012, ISO/IEC 40500:2025, WCAG as ISO standard

Simply put

ISO/IEC 40500 is the international standard version of the Web Content Accessibility Guidelines (WCAG), published jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It contains the same technical content as the corresponding WCAG document from the W3C's Web Accessibility Initiative, allowing organizations to reference WCAG through the formal ISO standards framework. The standard has been updated over time: the original 2012 edition adopted WCAG 2.0, and a second edition published in 2025 adopts WCAG 2.2.

Formal definition

ISO/IEC 40500 is an International Standard that adopts the W3C's Web Content Accessibility Guidelines verbatim, providing an ISO/IEC-branded equivalent to WCAG. The first edition, ISO/IEC 40500:2012, was identical to WCAG 2.0. In 2025 a second edition, ISO/IEC 40500:2025, was approved and published; per W3C, it is identical to the October 2023 version of WCAG 2.2, and the second edition cancels and replaces the 2012 first edition, which was technically revised. As with WCAG, the standard defines success criteria organized under conformance levels A, AA, and AAA, with Level AA most commonly cited as a target. The underlying WCAG documents remain freely available from the W3C. Adoption as an ISO/IEC standard reflects formal international standardization and does not by itself establish legal requirements in any jurisdiction; applicable obligations arise from the relevant laws, regulations, agency guidance, or contractual terms in a given context. Consult qualified legal counsel and current rulemaking for compliance determinations.

Why it matters

ISO/IEC 40500 gives organizations a way to reference the Web Content Accessibility Guidelines (WCAG) through the formal international standards framework maintained by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). For enterprises, government bodies, and procurement teams that already work within ISO-based quality and standards processes, this matters because it lets them cite web accessibility requirements using the same standardization language they use for other technical obligations. The content is not a separate or competing set of rules: ISO/IEC 40500 adopts WCAG verbatim, so conforming to it means meeting the corresponding WCAG success criteria.

The standard has evolved to track WCAG itself. The first edition, ISO/IEC 40500:2012, was identical to WCAG 2.0. A second edition, ISO/IEC 40500:2025, was approved and published in 2025 and, per the W3C, is identical to the October 2023 version of WCAG 2.2; this second edition cancels and replaces the technically revised 2012 first edition. Because of this update, treating ISO/IEC 40500 as though it still reflects only WCAG 2.0 is no longer accurate for the current edition. Organizations referencing the standard should be explicit about which edition and which WCAG version they mean.

Importantly, adoption as an ISO/IEC standard reflects formal international standardization; it does not by itself create legal requirements in any jurisdiction. Whether ISO/IEC 40500, WCAG, or a specific version and conformance level applies to a given organization depends on the relevant laws, regulations, agency guidance, or contractual terms in that context. Conformance with the technical criteria also does not by itself guarantee an accessible experience for all users or immunity from legal claims, and it is not legal advice. Organizations should consult qualified legal counsel and current rulemaking when making compliance determinations.

Who it's relevant to

Procurement and vendor management teams

Teams that specify requirements in contracts and tenders may prefer to reference ISO/IEC 40500 because it fits existing ISO-based procurement language. When doing so, they should state the specific edition (2012 for WCAG 2.0, or 2025 for WCAG 2.2) and the target conformance level, since the standard has been updated over time.

Compliance officers and legal counsel

Those assessing obligations should understand that ISO/IEC 40500 is technically identical to the corresponding WCAG version but does not itself establish legal requirements. Applicable duties arise from the relevant laws, regulations, agency guidance, or contracts in a given jurisdiction, and determinations should involve qualified legal counsel and review of current rulemaking.

Accessibility engineers and QA testers

Practitioners can apply the same WCAG success criteria, techniques, and conformance levels (A, AA, AAA) when evaluating against ISO/IEC 40500. Because the current second edition corresponds to WCAG 2.2, teams should confirm which edition applies and should combine automated checks with manual and assistive technology testing.

International and multi-jurisdiction organizations

Organizations operating across borders may value ISO/IEC 40500 as an internationally recognized reference point equivalent to WCAG. It can support consistent internal standards, though specific obligations still depend on local law and contractual terms in each market.

Inside ISO/IEC 40500

ISO/IEC 40500 (overview)

An International Standard, published jointly by ISO and IEC, that adopts the W3C Web Content Accessibility Guidelines (WCAG) verbatim as an ISO/IEC standard. It gives WCAG the status of a formal international standard, which can be useful in jurisdictions and procurement processes that reference ISO/IEC standards. It is a technical standard, not a law.

First edition (ISO/IEC 40500:2012)

The original edition, which adopted WCAG 2.0 as published by the W3C. It reproduced WCAG 2.0's success criteria and conformance model without technical modification.

Second edition (ISO/IEC 40500:2025)

A revised edition, published in 2025, that corresponds to WCAG 2.2 as published by the W3C. Practitioners should confirm which edition a given requirement, contract, or regulation references, since the applicable success criteria differ between editions.

Success criteria and conformance levels

Because the standard adopts WCAG, it carries WCAG's testable success criteria organized under three conformance levels: A, AA, and AAA. AA is the level most commonly cited as a target in policies and settlements. The specific set of success criteria depends on which WCAG version the applicable edition adopts (WCAG 2.0 for the 2012 edition, WCAG 2.2 for the 2025 edition).

Relationship to the W3C WCAG

The content of ISO/IEC 40500 is the WCAG text itself; the W3C remains the originating authority for WCAG and publishes supporting materials such as Understanding documents and techniques. Which WCAG version is reflected depends on the ISO/IEC 40500 edition in force.

Relationship to law and regulation

ISO/IEC 40500 is a voluntary technical standard. It is not itself the ADA, Section 508, or any other law. Some regulations, procurement frameworks, or agency guidance may reference WCAG or ISO/IEC 40500 as a benchmark, but that reference and its legal effect depend on the specific jurisdiction and instrument.

Common questions

Answers to the questions practitioners most commonly ask about ISO/IEC 40500.

Does ISO/IEC 40500 only reflect WCAG 2.0?

Not anymore. The original edition, ISO/IEC 40500:2012, was identical to WCAG 2.0. However, a second edition, ISO/IEC 40500:2025, was published and corresponds to WCAG 2.2 as of October 2023. When referencing ISO/IEC 40500, it is important to specify which edition you mean, because the technical content differs between the 2012 and 2025 versions. Confirm the current edition and its scope directly with ISO before relying on it.

If I conform to ISO/IEC 40500, does that also mean I meet WCAG 2.1 and WCAG 2.2?

It depends on the edition. Conforming to ISO/IEC 40500:2012 aligns with WCAG 2.0 and does not by itself cover the success criteria added in WCAG 2.1 or 2.2. Conforming to the second edition, ISO/IEC 40500:2025, corresponds to WCAG 2.2, which incorporates the criteria introduced across 2.1 and 2.2. Because the two editions map to different WCAG versions, you should verify which edition you are targeting and cite the corresponding WCAG version explicitly.

Which edition of ISO/IEC 40500 should we cite in a procurement or compliance document?

State the specific edition and its year, since ISO/IEC 40500:2012 corresponds to WCAG 2.0 and ISO/IEC 40500:2025 corresponds to WCAG 2.2. Referencing the standard without an edition can create ambiguity about which set of success criteria applies. Where a project or contract requires a particular WCAG version, name that version alongside the ISO edition, and consult qualified counsel or your procurement authority for jurisdiction-specific requirements.

Does adopting ISO/IEC 40500 satisfy legal accessibility requirements such as those associated with the ADA or Section 508?

Conforming to ISO/IEC 40500 is a technical benchmark, not a legal safe harbor. In the US, the ADA is a civil rights law that does not itself codify detailed web technical specifications, while Section 508 applies to federal agencies and covered federal contexts. Whether ISO/IEC 40500 conformance helps meet a given obligation depends on the applicable authority, regulation, and current guidance. This is not legal advice; consult qualified legal counsel for your specific situation.

Can we verify ISO/IEC 40500 conformance through automated testing alone?

No. Automated tools detect only a portion of accessibility issues, and conforming to the standard's success criteria generally requires manual evaluation and testing with assistive technologies. Automated checks should be treated as one part of a broader testing process rather than a complete measure of conformance.

Does meeting ISO/IEC 40500 guarantee that our content is usable by all people with disabilities?

Meeting the success criteria referenced by ISO/IEC 40500 does not guarantee an accessible experience for every user. Conformance and real-world usability are distinct; a page can satisfy the criteria and still present barriers in practice. Usability testing with people who have disabilities is commonly recommended alongside conformance testing to identify issues the criteria may not surface.

Common misconceptions

ISO/IEC 40500 only reflects WCAG 2.0.

That was true only of the first edition (2012). A second edition, ISO/IEC 40500:2025, corresponds to WCAG 2.2. When someone cites ISO/IEC 40500, you should confirm which edition and therefore which WCAG version applies.

Conforming to ISO/IEC 40500 makes a website legally compliant with the ADA or Section 508.

ISO/IEC 40500 is a voluntary technical standard, not a law. Meeting its success criteria may help demonstrate accessibility efforts, but it does not by itself guarantee compliance with the ADA, Section 508, or any other legal framework, which are enforced through their own statutes, regulations, and case law. Consult qualified legal counsel for your jurisdiction.

Meeting ISO/IEC 40500's success criteria means the site is fully accessible and usable for everyone.

Conformance to success criteria is not the same as a good experience for all users. Automated testing detects only a portion of issues; manual review and testing with assistive technologies are generally needed to evaluate real-world usability.

Best practices

Confirm which edition of ISO/IEC 40500 is being referenced (2012, corresponding to WCAG 2.0, or 2025, corresponding to WCAG 2.2) before treating it as a requirement, since the applicable success criteria differ.

Specify a target conformance level explicitly, since AA is the level most commonly cited as a target rather than assuming a default.

Combine automated testing with manual review and assistive technology testing, because automated checks detect only a portion of accessibility issues.

Treat ISO/IEC 40500 as a technical benchmark, not as legal compliance, and consult qualified legal counsel to understand how the ADA, Section 508, or other applicable authorities apply to your context.

When citing the standard in contracts, policies, or procurement, reference the specific edition and WCAG version to avoid ambiguity about which criteria apply.

Monitor updates from the W3C and ISO/IEC, as WCAG and its adopted ISO/IEC editions evolve and requirements can change through subsequent revisions, regulation, and case law.