What the New OFAC-OFSI Comparative Overview Means for Maritime Sanctions Compliance

At a Glance

• On June 23, 2026, the U.S. Office of Foreign Assets Control (OFAC) and the UK Office of Financial Sanctions Implementation (OFSI) published a joint comparative overview of their respective sanctions regimes, the most substantive product to date from the OFAC-OFSI Enhanced Partnership established in October 2022.
• The publication signals continued operational coordination between the two leading Western sanctions enforcers at a moment when the EU’s 21st sanctions package is also working through adoption, creating a multi-jurisdictional enforcement environment that maritime compliance teams need to navigate carefully.
• The guidance maps key differences across terminology, sanctions types, jurisdictional reach, recordkeeping requirements, reporting obligations, enforcement frameworks, and the calculation of ownership thresholds for non-listed entities, with each carrying practical implications for how maritime compliance screening should be structured.
• OFAC’s 50% Rule applies to property interests owned in the aggregate by one or more blocked persons, while OFSI’s 50% requirement generally does not aggregate across different designated persons, creating different ownership-based exposure outcomes for the same vessel ownership structure.
• Both regimes apply strict liability standards for civil sanctions penalties, meaning maritime operators can be held liable for sanctions exposure even without knowledge that a transaction was prohibited, raising the operational stakes for screening accuracy.
• The compliance environment shaped by these regimes is operating against a maritime data backdrop where GPS jamming has compromised AIS-based vessel positioning across four major seas, making sensor-verified intelligence increasingly necessary to support defensible screening decisions under either framework.

The OFAC-OFSI Publication in Context

The U.S. Department of the Treasury’s Office of Foreign Assets Control (OFAC) and His Majesty’s Treasury’s Office of Financial Sanctions Implementation (OFSI) are the offices responsible for enforcing economic sanctions implemented by the United States and the United Kingdom, respectively. The two offices established the OFAC-OFSI Enhanced Partnership in October 2022, committing to closer operational coordination through joint products that help the private sector understand its obligations under both regimes.

The comparative overview published on June 23, 2026, is the most substantive output of that partnership to date. It maps the practical mechanics of both sanctions frameworks side by side, covering terminology, sanctions types, jurisdictional reach, recordkeeping requirements, reporting obligations, enforcement processes, ownership rules, and the licensing frameworks for activities that would otherwise be prohibited.

The publication arrives in a particularly active period for maritime sanctions. The EU’s 21st sanctions package was proposed on June 9, 2026, with bunkering-specific provisions targeting vessels that assist the Russian shadow fleet. The UK followed on June 16, 2026, with its own package designating 27 additional tankers and several shipping companies. The OFAC-OFSI publication on June 23 closes a three-week regulatory window during which all three of the major Western sanctions jurisdictions tightened their measures, with the OFAC-OFSI guide making the operational mechanics of two of them more legible to maritime compliance teams.

For maritime operators, the practical question the publication raises is not whether to comply with OFAC or OFSI sanctions. Maritime trade involving U.S. dollars, U.S.-incorporated entities, UK companies, or UK-flagged vessels routinely brings operators within the scope of both regimes simultaneously. The question is how to structure compliance screening, documentation, and decision-making in ways that satisfy both frameworks without falling into the practical gaps between them.

What Maritime Compliance Teams Need to Know

The comparative overview surfaces several substantive differences between OFAC and OFSI that have direct operational implications for maritime sanctions screening.

Terminology Differences That Affect Compliance Documentation

OFAC and OFSI use different vocabulary for substantively similar concepts. OFAC refers to “sanctions programs,” “violations,” “blocking” property, and “Specially Designated Nationals” (SDNs). OFSI refers to “sanctions regimes,” “breaches,” “freezing” assets, and “designated persons” (DPs). The obligations overlap significantly, but the documentary language differs.

For maritime compliance teams, the implication is that compliance files, internal procedures, and external communications need to use the right terminology for the right regime. A compliance file referring to “blocking” a vessel under UK sanctions misuses the term, even if the operational action is correct. Cross-regime compliance documentation should reflect both vocabularies precisely.

Different Sanction Types Create Different Operational Constraints

OFAC employs six distinct sanctions categories: 

• List-based blocking sanctions.
• List-based non-blocking sanctions.
• Sector-based sanctions.
• Government blocking.
• Jurisdiction-based sanctions.
• Secondary sanctions. 

OFSI employs three: 

• List-based financial sanctions.
• Sectoral sanctions.
• Directions. 

The OFAC-OFSI guide notes specifically that OFSI does not have broad jurisdiction-based sanctions where most activity involving a specific jurisdiction is prohibited.

For maritime operators, this means that the same vessel or transaction may carry different sanctions exposure under each regime. A vessel operating in a jurisdiction subject to broad U.S. sanctions may face OFAC exposure even where no specific designation applies, while the same vessel may face UK exposure only if specific designations are in place. Screening logic that does not account for these structural differences may produce inconsistent results across regimes.

Jurisdiction Reaches Beyond National Borders

Both OFAC and OFSI sanctions apply beyond their respective national borders. OFAC sanctions apply to all U.S. citizens and permanent residents regardless of location, U.S.-incorporated entities and their foreign branches, transactions within or transiting the United States, and certain non-U.S. persons through programs covering causation, evasion, and reexports. OFSI sanctions apply to all UK persons regardless of location, UK-incorporated entities and their foreign branches, activity within UK territorial waters, and activity by non-UK persons with a “UK nexus.”

For maritime operators, the practical consequence is that a single voyage may trigger compliance obligations under both regimes simultaneously. A cargo loaded in the U.S. and discharged in a UK port, transported on a vessel chartered by a U.S. entity and insured by a UK underwriter, sits within both jurisdictions’ reach. Compliance screening that addresses only one regime leaves the other exposure unmanaged.

The 50% Ownership Rules Differ in Material Ways

Both OFAC and OFSI apply ownership thresholds to extend sanctions to non-listed entities, but the calculations diverge in important ways.

Under OFAC’s 50% Rule, an entity is itself considered blocked when 50% or more of it is owned by blocked persons, directly or indirectly. The 50% threshold can be reached by a single blocked person or by multiple blocked persons whose ownership stakes combine to reach the threshold. OFAC’s rule applies to ownership but not to control.

Under OFSI’s 50% requirement, an entity is subject to UK sanctions where a designated person holds more than 50% of that entity’s shares or voting rights, directly or indirectly. OFSI’s requirement does not generally apply when the ownership stakes of multiple different designated persons combine to reach the 50% threshold. However, OFSI also considers entities controlled, directly or indirectly, by designated persons to be sanctioned, where control means the right to appoint or remove a majority of the entity’s board, or where it is reasonable to expect the designated person can ensure the entity’s affairs are conducted in accordance with their wishes.

For maritime ownership screening, this difference matters. A vessel-owning entity in which two different designated persons hold 30% each may be subject to OFAC blocking sanctions (because the aggregate 60% exceeds the 50% threshold) but not subject to UK sanctions on that basis (because no single designated person holds more than 50%). The same vessel may carry different exposure outcomes under each regime, requiring screening logic that accounts for both calculations.

Recordkeeping and Reporting Requirements Carry Different Timelines

OFAC requires persons engaging in transactions subject to its sanctions to keep records for at least 10 years. UK financial sanctions legislation does not specify a retention period but requires records to be retained in accordance with other UK financial recordkeeping requirements. OFAC requires reporting of blocked property actions within 10 business days, with annual reporting on the Annual Report of Blocked Property due September 30. OFSI requires reporting “without delay” for certain transactions, with annual frozen asset reporting due November 30.

For maritime operators, financial institutions, marine insurers, and other parties handling vessels, cargoes, or transactions that may touch either regime, this means compliance recordkeeping and reporting calendars need to satisfy both frameworks. A single vessel detention or blocked transaction may trigger reporting obligations under both regimes on different timelines, with different documentation requirements. For banks and insurers that may discover sanctions exposure partway through a transaction or claim lifecycle, the requirement to report under multiple regimes simultaneously can create operational complexity that AIS-only screening could not have anticipated.

Enforcement Frameworks Apply Strict Liability

Both regimes apply strict liability standards for civil sanctions penalties. OFAC may impose civil penalties for apparent sanctions violations regardless of whether the person had knowledge that the transaction was prohibited. OFSI applies the same strict liability standard for sanctions breaches occurring after June 15, 2022, with a knowledge or reasonable-cause-to-suspect test applying to breaches before that date.

For maritime operators, strict liability means that adequate screening is not just a best practice. It is an operational baseline for managing exposure. A compliance failure that produces a sanctions violation can carry penalties even where the operator did not know the counterparty vessel was sanctioned or the activity was prohibited. The defensibility of the screening methodology behind compliance decisions is what supports mitigation arguments in enforcement proceedings.

Voluntary Disclosure Policies Create Mitigation Pathways

Both regimes encourage voluntary disclosure of sanctions violations or breaches, with the disclosure treated as a mitigating factor in determining enforcement responses. OFAC may apply a 50% reduction to the base civil penalty for qualifying voluntary self-disclosures. OFSI may apply up to a 30% reduction in the final monetary penalty amount.

For maritime operators that discover a potential sanctions exposure event after the fact, the operational question is whether to disclose voluntarily and to which regime first if both are implicated. The defensibility of the original screening methodology, the speed of detection after the event, and the quality of the documentation supporting both are what determine the mitigation outcome.

How GPS Jamming Complicates Compliance Under Both Regimes

A challenge sits beneath all of the regime-specific mechanics outlined above. The AIS-derived vessel data that maritime compliance screening typically depends on has been structurally compromised in jamming-affected regions across 2025 and 2026.

Approximately 978,000 GPS jamming events were recorded globally in Q1 2026, with 98% concentrated in the Middle East Gulf and more than 1,100 vessels directly affected. 

GPS jamming has injected false coordinates into AIS broadcasts across the Middle East Gulf, the Black Sea, the Mediterranean, the Red Sea, the Arctic, and Venezuelan waters. Vessels operating in jamming-affected areas may broadcast positioning data that places them at sanctioned ports they never visited, or may conceal sanctioned activity behind injected coordinates that show clean voyage histories.

For compliance teams operating under both OFAC and OFSI strict liability standards, this is a structural problem. A screening decision documented as “vessel was not at sanctioned port” based on AIS positioning data carries embedded uncertainty in jamming-affected regions, complicating the defensibility of the methodology that supported the decision. Whether the compliance file is reviewed by OFAC, OFSI, or both, the underlying data integrity question is the same: was the AIS evidence base reliable in the operating environment where the activity occurred?

The operational answer is multi-source intelligence that does not depend on cooperative signaling from the vessel. Sensor-verified vessel activity through satellite imagery (SAR and EO), radio frequency detection, and behavioral context provides a defensible evidence base that holds up across both regimes, even when AIS data is unreliable.

How Windward Helps

Windward’s Maritime AI™ Platform provides the vessel verification, behavioral risk profiling, and multi-source intelligence that maritime compliance teams need to operate defensibly across U.S., UK, and EU sanctions regimes.

Know Your Vessel (KYV™) consolidates the vessel-specific risk picture, including ownership chains, flag history, behavioral patterns across multiple voyages, and identity changes that map to shadow fleet activity. Multi-Source Intelligence fuses AIS, SAR, EO, and RF into one operational picture that verifies what a vessel actually did, independent of what its AIS broadcasts show. Document Validation supports verification of vessel filings, registry status, and other documentation that compliance screening relies on.

For maritime compliance teams operating across multiple regimes, the operational fit is direct. Sensor-verified vessel activity supports screening decisions that hold up under either OFAC or OFSI strict liability standards. Behavioral context across multiple voyages surfaces patterns that single-event screening would miss, including ownership patterns that may carry different exposure outcomes under different jurisdictions’ 50% calculations. The cumulative effect is a compliance posture that operates defensibly across the multi-jurisdictional environment.

The presence of a vessel in a GPS jamming-affected area is not, by itself, a behavioral risk indicator. GPS jamming is something happening to a geographic area, not something a vessel is doing. The vessel’s risk profile is assessed independently based on its own behavioral patterns and operating history, separate from the jamming environment in which it may be operating.

What to Watch Next

Several developments in the coming weeks are worth tracking.

The EU is targeting Council adoption of the 21st sanctions package by July 15, 2026. The final text adopted may differ from the proposal in ways that affect the practical scope of the bunkering-targeted measures and the broader shadow fleet provisions. Maritime operators with EU touchpoints should track the final adopted text closely.

OFAC enforcement priorities through the remainder of 2026 will signal which categories of maritime activity face the most concentrated U.S. enforcement attention. The temporary U.S. waivers on Russian oil-related activity during the Hormuz conflict and the issuance of OFAC General License X on June 22, 2026, authorizing certain transactions involving Iranian-origin crude oil and petroleum products through August 21, 2026, indicate that OFAC enforcement may diverge from EU and UK positions in specific market-condition windows, complicating multi-regime alignment in practice.

OFSI’s enforcement posture and any further joint OFAC-OFSI products will signal how the Enhanced Partnership continues to develop operationally. The June 23 publication is structured to be a foundational document rather than a final product, with additional guidance likely to follow on specific compliance issues.

Maritime compliance teams that build their screening, documentation, and decision-making to satisfy the more demanding standards across all relevant regimes are positioned to operate through the current environment. Teams that calibrate to only one regime, or to a single point in time within any given regime, face exposure that may not surface until enforcement action reveals what was missed.