What is an OFAC sanctions check?

A sanctions check queries the SDN list to see whether a counterparty is blocked before a transaction proceeds.

TL;DR

TL;DR: An OFAC sanctions check compares a name or wallet against the SDN list and returns a decision: ALLOW for clean, BLOCK for flagged.

Manual vs automated

A sanctions check answers one question: is this counterparty blocked? The manual version is a search of the SDN list, the Specially Designated Nationals and Blocked Persons list maintained by OFAC. The automated version makes the same comparison via an API, submitting a name or wallet and receiving a decision in under 100 ms.

What gets checked

The check covers names on the SDN list, currently 19,218 entries, and crypto wallets, of which OFAC has listed 947. A good check also applies the 50 Percent Rule, so an entity owned 50% or more by a blocked person is treated as blocked. Name-only searches miss wallets, which is why a wallet-aware check matters for crypto payments.

When to run it

Run the check right before the money moves. For an AI agent that means screening the counterparty before the agent pays, then branching on the result. Because strict liability applies, the check is not a nice-to-have; it is the control that separates an ordinary payment from a potential enforcement action.

What a check does not do

A screening check reports whether a counterparty is on the list; it does not move money or make policy. Money-moving tools such as x402, AP2, ACP, and Coinbase AgentKit handle the transfer, but they do not screen. The check is the control you place in front of them, and it must be added deliberately.