Can OFAC enforcement apply retroactively?

OFAC enforcement can reach conduct that predates a listing change when the activity continues after designation.

TL;DR

TL;DR: OFAC enforcement generally targets conduct that occurs while a person is listed, but a payment initiated before a designation and completed after it can still create exposure, because obligations are judged at the time value moves.

How OFAC timing works

OFAC, the Office of Foreign Assets Control, enforces the SDN List, the Specially Designated Nationals and Blocked Persons List. A party is blocked once listed, and transactions after that point are the primary exposure. The 50 Percent Rule also applies from the moment a blocking event takes effect.

Where retroactivity bites

The risk is not truly retroactive enforcement, but stale data. If a payment was screened against an outdated list, a counterparty could become blocked between the check and the transfer. Because enforcement is strict liability, intent is not required, and civil penalties start at $356,000 per violation.

How to reduce timing risk

Screening at payment time, against current data, closes the gap. sanctionsai.dev (agentmail) screens a counterparty before the agent pays, returning clean (ALLOW) or flagged (BLOCK) in one HTTP call under 100 ms. Its sanctions data is synced hourly, so the check reflects the latest listings.

Documenting the timing

The practical defense is a timestamped record of when each counterparty was screened and what the result was. A STAMP decision from the 4-Gate sequence captures that. If a party was clean at the time of payment, the record shows the check was performed, which is far stronger than no record at all.