For any maritime business, a sanctions screening programme is only as good as the lists it screens against. A counterparty, a vessel, a beneficial owner or a port operator that sits on the wrong list can freeze a payment, void cover, expose a charterer to enforcement action and put a ship off-hire while lawyers untangle the exposure. The difficulty is that there is no single global list. A shipowner, charterer, broker, bank or marine insurer must screen against several overlapping regimes at once, each maintained by a different authority, each with its own rules about who is caught. This guide explains the main lists a maritime operator should screen against, what a designation actually means, where secondary sanctions risk comes from, and how list changes need to flow into a working screening programme.
The four regimes that matter most
Most maritime sanctions exposure traces back to four authorities. You should treat all four as live inputs to screening, not as alternatives.
- United States: the Office of Foreign Assets Control (OFAC). OFAC, part of the US Department of the Treasury, maintains the Specially Designated Nationals and Blocked Persons List (the SDN List). It also runs sectoral and programme-specific lists, including the Sectoral Sanctions Identifications (SSI) List and the Non-SDN lists, which restrict particular dealings rather than blocking a party outright.
- United Kingdom: the UK Sanctions List. From 28 January 2026 the UK Sanctions List, maintained by the Foreign, Commonwealth and Development Office (FCDO), became the single source for all UK sanctions designations. It replaced the long-standing OFSI Consolidated List of Asset Freeze Targets, which closed on that date and is no longer updated. The Office of Financial Sanctions Implementation (OFSI), part of HM Treasury, remains the body that implements and enforces UK financial sanctions.
- European Union: the Consolidated list of persons, groups and entities subject to EU financial sanctions. Published by the European Commission and distributed through its Financial Sanctions Files (FSF) service, this is the reference list for EU asset freezes and related restrictions.
- United Nations: the UN Security Council Consolidated List. This brings together every individual and entity subject to measures imposed by the Security Council. UN designations are then implemented through EU regulations and national instruments, so the same name often appears across several lists at once.
If your screening covers only one jurisdiction, you have a gap. A US-touching dollar payment, a UK-flagged or UK-insured hull, and an EU port call can each pull a different regime into the same voyage.
What a designation actually means
A designation is not a warning label. When a person, company or vessel is listed on the SDN List, the UK Sanctions List, the EU consolidated list or the UN Consolidated List, the practical effect is usually an asset freeze and a prohibition on dealing. For US purposes, all property and interests in property of an SDN that are subject to US jurisdiction are blocked, and US persons are generally prohibited from transacting with that party. Under UK and EU asset freezes the effect is comparable: funds and economic resources must be frozen and may not be made available, directly or indirectly, to the designated party.
For ships, OFAC and other authorities can list a vessel itself as blocked property. Designated vessels are identified by their International Maritime Organization (IMO) number, alongside flag, vessel type and year of build, because the IMO number stays with the hull through changes of name, owner and flag. That makes the IMO number the single most reliable screening key for a ship, and the reason name-only vessel screening is unsafe.
The OFAC 50 per cent rule and hidden exposure
The hardest sanctions exposure is the exposure you cannot see on the face of a list. OFAC's 50 Percent Rule holds that any entity owned, directly or indirectly, 50 per cent or more in aggregate by one or more blocked persons is itself treated as blocked, even though it does not appear on the SDN List by name. Ownership aggregates: if two SDNs each hold 25 per cent of a company, the company is caught. It also applies through layers, so a designated owner sitting two or three corporate tiers up still contaminates the subsidiary you are actually dealing with.
OFAC does not publish a list of these majority-owned entities, so the burden falls on the screening party to map beneficial ownership. The UK and EU apply their own ownership-and-control tests with a broadly similar effect. For maritime work this is where most surprises live: the named charterer or port agent is clean, but the holding company, the technical manager or the ultimate beneficial owner is not. Effective screening therefore has to reach beyond the immediate counterparty into the ownership and control structure behind it.
Secondary sanctions and the wider chilling effect
Secondary sanctions extend exposure to non-US parties. Rather than prohibiting US persons from a transaction, they threaten foreign companies and financial institutions with loss of access to the US financial system if they deal with certain sanctioned targets. A non-US owner or charterer with no US nexus can still be exposed if a counterparty, cargo or trade is designated as carrying secondary-sanctions risk. The practical result is a chilling effect well beyond the letter of any single list: banks, insurers and flag registries routinely decline business that is technically lawful for them but carries secondary-sanctions risk. Screening that looks only for primary, name-on-list matches will miss this category of risk entirely.
How list changes flow into a screening programme
Sanctions lists are not static reference data. Authorities add, amend and remove designations continuously, and a name added this morning can change the legality of a fixture you signed last week. A screening programme has to treat list changes as a live feed, not a quarterly download. In practice that means:
- Screen against current, consolidated source data. Pull from the authoritative publications: OFAC's SDN and consolidated lists, the FCDO UK Sanctions List, the EU consolidated list and FSF service, and the UN Consolidated List. Retire dead sources promptly: any UK process still keying off the closed OFSI Consolidated List needs to move to the UK Sanctions List and its Unique ID.
- Screen on stable identifiers, not just names. Use IMO numbers for vessels and, where available, registration and entity identifiers for companies, so transliteration and alias variations do not let a match slip through.
- Re-screen, do not just screen once. Run counterparties and vessels again on each material event and periodically over the life of a relationship, because a clean party can be designated mid-voyage.
- Look through ownership and control. Apply the 50 per cent and ownership-and-control tests to beneficial owners, managers and parent entities, not only the contracting name.
- Keep an audit trail. Record what was screened, against which list version, on what date, and what the analyst concluded, so a decision can be defended later.
Where Verihelm helps
Sanctions screening fails quietly: a stale list, a name-only vessel check or an unmapped beneficial owner produces a clean result that is wrong. Verihelm is an analyst-verified maritime intelligence platform that brings the regimes above into one screening picture, matching counterparties and vessels against current OFAC, UK, EU and UN designations, working from IMO numbers and entity identifiers rather than names alone, and surfacing the ownership and control structure behind a counterparty so 50 per cent and secondary-sanctions exposure does not stay hidden. Because every flag is checked by an analyst before it reaches you, the platform cuts the false positives that slow a compliance team while making sure real exposure is not missed. See how Dryad Global approaches sanctions and compliance screening for maritime operators.