According to the W3C Web Accessibility Initiative (WAI) accessibility policies need to consider procured or syndicated third-party content. This is particularly relevant for third-party content that provides essential parts of a website. For example, this could include credit card payment services, video streaming channels, or online mapping services.
Site owners are responsible for ensuring accessibility or for providing accessible alternatives. This is true even if site owners don’t have full control over such content and services.
For example, social media feeds may need to be monitored or moderated to ensure accessibility. See the WCAG 2.1 conformance requirement for complete processes
and the concept of conforming alternate version for more background.
Source: W3C Web Accessibility Initiative
According to United States Department of Justice, Civil Rights Division, Title II of the ADA law prohibits discrimination in the provision of any aid, benefit or service provided by public entities directly or through contractual, licensing, or other
arrangements (28 CFR 35.130(b)(1)) – Section 504 has similar provisions. If a district or agency uses a third-party website for services (such as food services account to allow payments
or credit(s) – the district or agency could be liable to ensure accessibility to the third-party’s website and web components. If the link is for informational or resources purposes only,
the District or agency may not be required to ensure accessibility, though the Office of Civil Rights (OCR) has not recognized this argument in recent Resolution Agreements. Best practice
is to ensure that any third-party vendor you use should have an accessible website.
Source: United States Department of Justice, Civil Rights Division