Should an agency guarantee WCAG conformance in a client contract?
Promising WCAG conformance in a client contract sounds like a selling point, until a demand letter tests it. Guarantee the process instead: continuous monitoring, documented remediation, and an evidence trail that proves diligence.
A guarantee is a liability, not a feature
Every few months an agency principal asks whether putting a WCAG conformance guarantee in client contracts would help close deals. It feels like a strong move. The client is worried about demand letters, the agency is confident in its work, and a guarantee seems like the shortest path to a signature. The problem is that a conformance guarantee promises something the agency cannot fully control.
WCAG conformance is a property of a living website, not a deliverable you hand over once. The day the agency ships an accessible theme, the client can install an app, publish a blog post with an unlabeled image, or paste a third-party embed that breaks three success criteria before lunch. A guarantee written against the launch state becomes a liability the moment anyone else touches the site. And someone always touches the site.
Demand letter firms know this. When a letter arrives citing barriers on a site the agency guaranteed, the first question the client's attorney asks is what the guarantee actually covered. If the contract promised conformance and the site is not conformant, the agency is not just embarrassed. It is potentially on the hook for the settlement the guarantee was supposed to prevent.
What conformance actually means
Part of the confusion is that WCAG conformance sounds binary and permanent, like a certification. It is neither. A site conforms at a level, for a defined set of pages, at a point in time, under specific testing conditions. Change any of those variables and the claim has to be re-evaluated. Agencies that talk about conformance as a permanent badge are setting expectations no website can meet.
This matters for contracts because vague guarantees get interpreted against whoever wrote them. "The site will be WCAG 2.2 AA conformant" reads to a client as a promise that lasts. It reads to a judge as a warranty. Neither reading helps the agency when the client's marketing intern uploads a carousel with no alt text in February.
The honest framing is narrower: the agency delivered work that met WCAG 2.2 AA at launch, verified by defined testing, across an agreed page set. That is a factual claim about work performed. It is defensible, it is provable, and it does not extend into the future where the agency has no control.
Guarantee the process, not the outcome
The strongest thing an agency can actually promise is a process. Continuous monitoring catches regressions the week they appear instead of the quarter they get cited. Documented remediation turns each fix into evidence. An evidence trail of scans, tickets, and resolutions is what attorneys actually want to see when a demand letter arrives, because it proves diligence rather than perfection.
Diligence is the real defense. Demand letter cases rarely turn on whether a site was perfectly conformant on the day the plaintiff visited. They turn on whether the brand can show it took accessibility seriously: regular testing, prompt fixes, a public feedback channel, an accessibility statement that matches reality. An agency that guarantees and delivers that process gives the client something more valuable than a conformance promise. It gives them a story that holds up.
This also aligns incentives correctly. A conformance guarantee makes every client-side content change the agency's problem. A process guarantee makes the agency the client's partner in catching problems early, which is work the agency can price as a retainer instead of absorbing as liability.
Contract language that protects both sides
Replace the guarantee with three specific commitments. First, the agency warrants that its deliverables met WCAG 2.2 AA at the time of delivery, verified by the testing method named in the statement of work. Second, the agency will run scheduled monitoring and report findings on a defined cadence. Third, the agency will remediate issues it introduced within a defined SLA, and will flag issues introduced by the client, apps, or third parties with recommended fixes.
Then add the boundary that makes it all work: the client acknowledges that content, apps, and third-party changes made outside the agency's work can affect conformance, and that the monitoring reports are the mechanism for catching them. This is not fine print to hide behind. It is the shared understanding that lets the retainer relationship function.
Clients rarely push back on this framing once it is explained. They did not want a legal warranty; they wanted to stop worrying about demand letters. A monitoring and remediation process with named SLAs stops the worry better than a guarantee, because it keeps working after launch day. Sell the process, document the process, and let the guarantee idea die in the proposal stage where it belongs.