Spending Limits and Policy Controls

Question 1

How do you set spending limits for an AI agent?

Accepted Answer

Put the limit where the agent cannot change it: in the wallet, account or payment credential, not in the prompt. Our post walks through building an enforced spending mandate step by step.

Question 2

How do you stop an AI agent from overspending?

Accepted Answer

Enforce the budget outside the agent: a hard limit in the account or credential, checked before each payment, plus limits on what it can find and buy. Our post covers each layer.

Question 3

What is a policy engine for AI agents?

Accepted Answer

A policy engine evaluates each action an agent proposes against a set of rules and returns allow or deny, separately from the agent itself. Rules cover spending limits, allowed recipients, merchant categories and approval thresholds. Because it runs outside the model, a manipulated agent cannot talk its way past it.

Question 4

How do you restrict an AI agent to specific merchants or categories?

Accepted Answer

Control the credential the agent pays with. Card programs can limit agent spending by merchant category, as Visa describes for its OpenAI collaboration, and virtual card numbers carry issuer-set controls such as amount limits. For delegated tokens, ACP ties each token to a single merchant through its allowance.

Question 5

How do you allowlist destinations an AI agent can pay?

Accepted Answer

Keep a list of addresses, accounts or merchants the agent may pay, and reject anything else before signing. Onchain, a smart account can enforce the list itself, using a validator or hook module under ERC-7579 to check each transaction. Add new destinations only through the owner, never through the agent.

Question 6

Should agent spending limits be enforced onchain or offchain?

Accepted Answer

Both, for different reasons. Onchain limits, enforced by a smart account or granted permissions such as ERC-7715 token allowances, hold even if the agent's software is compromised. Offchain checks are easier to change and can use context the chain cannot see, such as merchant category or user history. Put hard caps onchain and nuanced rules offchain.

Question 7

How do you require human approval above a threshold for agent payments?

Accepted Answer

Set a value above which the payment is held for a person: the agent prepares it, the policy pauses it, and an approver confirms or rejects it before it executes. Card programs support this; Visa lists required approvals among the controls for agent transactions. Require approval for first payments to new payees as well.

Question 8

How do you give an AI agent a corporate card safely?

Accepted Answer

Do not hand over the card number. Give the agent a virtual card or a network agent token with its own amount limits and, where possible, merchant limits, or a single-use number per purchase. Keep the controls with the issuer, where the agent cannot change them, and review its spending regularly.

Question 9

What controls do finance teams need before letting AI agents pay vendors?

Accepted Answer

Rules for who can authorize an agent and what it may pay, hard limits per payment and per period, a list of approved payees, separation between whoever sets limits and the agent, and records linking every payment to its approval. Visa's B2B agent pilot, for example, pays only invoices the buyer has already approved.

Question 10

What is a per-period budget for an AI agent and how does it reset?

Accepted Answer

A per-period budget caps an agent's total spending within a window, such as a day or a month, and resets to the full amount when the next window starts. Define the window precisely, including its time zone or UTC reference, and count every payment by its timestamp so the reset cannot be gamed.

Question 11

What is a business ceiling for AI agent spending?

Accepted Answer

A business ceiling is the most that all of an organization's agents together may spend in a period, above any single agent's budget. It stops many agents, each within its own limit, from adding up to more than the business intended, so it has to be enforced centrally across all of them.

Question 12

How fast must an agent payment policy check be?

Accepted Answer

Fast enough to sit inside the payment flow without being noticed, because it runs on every payment and card payments already expect real-time authorization and fraud monitoring. A check that is slow enough to be skipped, or moved after the payment, has lost its point; keep it simple enough to run synchronously.

Question 13

What should an agent see when a payment is denied by policy?

Accepted Answer

A clear, machine-readable denial: that the payment was refused, which rule it broke and whether it can be retried, for example after approval. A standard error format such as Problem Details for HTTP APIs helps the agent handle it correctly. Do not reveal more of the policy than the agent needs to act.

Question 14

How do you test AI agent spending policies before production?

Accepted Answer

Run them against simulated and testnet payments before production. Replay a set of payments that should pass and fail, including edge cases at the limits and around reset times, and check every decision. Ethereum's Sepolia testnet and x402's test facilitator let agents run real payment flows with tokens of no value.

Question 15

Can an AI agent change its own spending limits?

Accepted Answer

It should not be able to. Limits must sit where the agent has no write access, such as the account's onchain rules, the card issuer's controls or a policy service it can only query. Changing a limit should take the owner, through a separate channel, and every change should be logged.