When an AI agent buys the wrong product—or makes a purchase no one explicitly approved—the fallout isn’t just a customer service issue. It’s a liability problem the payments ecosystem isn’t fully prepared to handle.

In a PaymentsJournal Podcast, Jill Willard, CTO at IXOPAY, Rory Herriman, CTO and COO at Zip Co, and Christopher Miller, Lead Analyst of Emerging Payments at Javelin Strategy & Research, explored how liability may evolve as AI agents take on more responsibility in transactions.

A Multidimensional Problem

That question of liability quickly becomes a technical one: how do you even evaluate trust in an agent that isn’t human?

The first challenge is determining how to calculate a trust score for an AI agent that lacks a traditional human behavioral footprint. Any viable framework must extend beyond identity to include intent—and how that intent translates into behavior.

This isn’t just an engineering challenge; it’s also a cognitive one. Professionals in this space must rethink how they evaluate risk, developing new instincts that help them focus on the right signals.

“We have certain models, frameworks, and even language that professionals use to describe the vectors of risk,” Miller said. “As we think about the replacement of human actors with agentic actors, we lack instinct. The mere notion blocking bot traffic as a way of defending against fraudulent behavior stops being useful. It becomes anticommercial.”

Herriman added: “We have to approach it as a multidimensional problem. “It’s not just ‘Is this actor good?’ Even if the actor is good, there are other dimensions on top of the binary switches, a complexity that never disappears.”

Assigning Liability in a New Context

In the world of AI, merchants are steadily losing control over the checkout experience. Decision-making has shifted upstream. A consumer can now instruct agent not only to buy “blue shoes,” but to purchase them from a specific merchant.

This shift brings a corresponding liability. If an agent buys light blue shoes instead of dark blue, who is at fault? Today, that burden often falls on the merchant.

“We’ve seen some card brands, such as Amex, say that they’re going to accept liability for agentic transactions, which is an awesome development,” said Herriman. “But even if the liability fully shifts and the card brands take on more of that liability, there’s still a cost to shipping the wrong goods out. That can be the hard cost of the shipping fees or the operational cost to get the goods out the door, but it can also be at the cost of customer relationships.”

Liability will become a central issue for issuers, providers, and merchants in the coming years. Existing frameworks address stolen cards or unauthorized use of payment credentials. But when a consumer is dissatisfied with what an agent selected on their behalf, responsibility becomes far less clear.

A similar cycle emerged in early e-commerce. Merchants drove growth by offering generous return policies and absorbing the associated risk. Over time, return rates skyrocketed, leaving businesses with inventory that couldn’t be resold at full value.

Eventually, that broad assumption of liability narrowed. Companies began analyzing customer behavior and limiting privileges for high return users—an early example of risk-based personalization.

Responding to Complexity

Payments have never had a single, unified approach, and agentic commerce is no exception. Agents will operate across multiple protocols and may express preferences for how transactions are executed—for example, specifying which rewards card to use.

Orchestrators are working to simplify this complexity for merchants, who are primarily focused on selling products—not managing payments infrastructure. Meanwhile, agent developers are not necessarily optimizing for merchant interests.

“Merchants have to figure out how to participate in an ecosystem where they aren’t necessarily the reason why the products have been developed in the first place,” said Miller. “It’s a common position for merchants to be in. It was the same thing with adding features like Apple Pay.”

Enter the Unified Trust Layer

Merchants will need partners to help them adapt to this shifting landscape. IXOPAY is working to involve merchants early in the Unified Trust Layer initiative, fostering a mindset that balances both merchant and consumer priorities. This approach helped drive Zip’s partnership with IXOPAY.

“When we began talking about how agentic commerce and agentic payments were going to affect both of our businesses, it was fairly clear that those intersections were common,” said Herriman. “Throughout our network of 25,000-plus merchant partners, our focus is ensuring that in this new era of consumer payments, we’re able to show up with them with the same intentionality of protecting them and protecting fraud against them in the way that we do in the traditional shopping channels.”

At its core is the concept of a pre-transaction authorization query, allowing merchants to evaluate the trust score of an agent before completing a sale. This moves decision-making beyond a simple binary of approve or decline.

“With the trust score, you’ll be able to kind of get some insight into that agent within that particular transaction, and decide maybe to accept agentic transactions from this protocol, but not for this particular transaction,” said Willard. “It’s adding to that multidimensional layering that agentic commerce brings.”

Ongoing Evolution

The criteria for evaluating agents will evolve over time as new behavioral patterns—and new forms of fraud—emerge. Merchants and their technology partners will need to collaborate closely to build capabilities tailored to agentic commerce.

With improved risk models, new technological tools, and the integration of agent trust scores into existing workflows, merchants can shift from a default “no” to more nuanced, conditional approvals.

“It’s going to be a rocky road as the innovation continues to unfold and as a lot of these protocols come to life,” said Herriman. “But when we’re past those challenges, what does it really look for the merchant? A channel that opens up greater access to more customers through things like orchestrated shopping, which most merchants can’t participate in today.”

These opportunities will require new safeguards, including frameworks like the Unified Trust Layer. One thing is clear: merchants that want to remain competitive won’t be able to ignore what’s coming.

“They will end up needing to participate because it’s going to be such a big channel,” said Willard. “Regardless of if you open up to full agent bot shopping, you’re going to have to rethink your consumer experience on how they interact with you and your brand. It’s not a question of if they’re going to participate in agentic commerce. It’s by how much and when.”