What the EAA actually requires of publishers
and the June 2025 deadline that already passed
The European Accessibility Act (Directive (EU) 2019/882) applies to ebooks sold to consumers in the EU. Since 28 June 2025 an ebook placed on the market has to be accessible, and the accessibility information has to travel with it to the shop, so a reader can tell before buying whether the book will work for them.
What that means for a file
In practice the standard everyone converges on is EPUB Accessibility 1.1 with WCAG 2.1 Level AA. The concrete requirements are unglamorous: every image carries a text alternative or is properly marked decorative, the language is declared, the reading order is real, headings describe the structure honestly, navigation exists, and nothing depends on colour alone.
What it means for your metadata
The file's own package document should carry schema.org accessibility metadata (accessibilityFeature, accessibilityHazard, accessibilitySummary, accessMode). Your distribution feed should carry the matching ONIX Code List 196 values, because several channels read only the feed and never look inside the file.
The deadline already passed
That is not a reason to panic, and it is not a reason to claim something untrue. Enforcement is national and complaint-driven, and a publisher who is visibly working through a backlist with a documented process is in a very different position from one who claims conformance it cannot show. Fix in order of harm, record what you did, and never sign a claim you cannot evidence.