Screen counterparties against the OFAC Specially Designated Nationals list
domain: home.treasury.gov · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Download the current SDN list in machine-readable format from https://www.treasury.gov/ofac/downloads/sdn.xml (XML) or sdn.csv (CSV) — OFAC publishes updates whenever the list changes
Parse the SDN file to build a local index of names, aliases ('aka' entries), addresses, and identifying information (passport numbers, national IDs, vessel IMO numbers)
Implement fuzzy name matching against the index using a combination of exact match, normalized Unicode comparison, and phonetic or edit-distance algorithms to catch name variations and transliterations
For each counterparty screening hit, retrieve the full SDN entry details including 'programs' (the sanctions program such as SDGT or CUBA) and 'remarks' to assess whether the match is a true positive
Log every screening run with the date, the SDN list version used (check the file header date), the counterparty name queried, and the result — retain logs for at least 5 years per OFAC guidance
Known gotchas
OFAC does not provide a real-time REST API for SDN lookups; integrations that rely only on a one-time database load will miss new designations — you must re-download and re-index the SDN file every time it is updated, typically multiple times per week
The 50-percent rule means entities owned 50% or more by an SDN are themselves blocked even if not on the list; name-screening the SDN file alone is insufficient for thorough compliance — beneficial ownership data is also required
False positives from common names (especially transliterated Arabic, Persian, or Korean names) are frequent; a compliance workflow must include human review before blocking transactions, and OFAC provides a license process for disputed matches
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