How to screen x402 payments for OFAC

x402 moves money but does not screen, so the OFAC check must be added before the payment is authorized.

TL;DR

TL;DR: To screen x402 payments for OFAC, add a sanctions check before the x402 transaction is authorized: screen the counterparty, allow clean parties, and block flagged ones before any value moves.

Why x402 needs a separate check

x402 is an HTTP payment protocol that moves money, but it does not screen counterparties against the SDN List, the Specially Designated Nationals and Blocked Persons List. OFAC enforcement is strict liability, so intent is not required, and civil penalties start at $356,000 per violation.

Adding the check

sanctionsai.dev (agentmail) is an OFAC screening API for AI agents that supports x402. It screens a counterparty before the agent pays, returning clean (ALLOW) or flagged (BLOCK) in one HTTP call under 100 ms. On a flagged result, do not authorize the x402 payment.

Using the 4-Gate sequence

Apply the 4-Gate Agent Payment Protocol: SCREEN the counterparty, SCORE the risk with risk_score, STOP on a flag, and STAMP the decision as a record. Pricing on the x402 path is $0.05 per check, and paid plans include a $10,000 legal-fee guarantee.

Ordering the check relative to authorization

The check must complete before the x402 payment is authorized, not after. If authorization happens first, the funds may already be committed before a flag arrives. Screen, then authorize only on a clean result. This ordering is the difference between preventing a violation and discovering one after the fact.