Could a small website end up paying for an ADA accessibility claim?

There is a real possibility of legal costs, but nobody can give you a reliable probability from the size of the site alone. A claim might be resolved by fixing barriers, or it might involve legal fees or a settlement. Don't assume that fixing a problem automatically makes a claim or its costs disappear.

What rules apply and who could be responsible depend on the situation and jurisdiction. If you receive a demand or legal notice, get advice from a qualified lawyer rather than relying on a blanket deadline or a promise that small sites won't be sued.

I'd focus first on building accessibility in from the start. Retrofitting a large site can be a lot more work than choosing sensible patterns early, and this is about people being able to use the site, not just avoiding a claim.

Use semantic HTML, make controls usable with a keyboard, and use ARIA correctly where it's needed. Learn the Web Content Accessibility Guidelines and test with real assistive technology as well as automated tools.

If you're building for clients, spell out what accessibility work is included, who supplies the content, and what testing will be done. That gives both sides a clearer idea of the scope instead of treating compliance as an invisible extra.

A contract can also address responsibility and indemnification, but a clause between you and a client doesn't necessarily eliminate liability to someone else. Have a lawyer review the wording rather than assuming a hold harmless clause solves everything.

There are different views about how common these claims are and whether some are driven mainly by settlement pressure. The sources don't establish a rate for small sites, so I'd be wary of both panic and assurances that the risk is nearly zero.