Tokyo MOU Revises Flag State and RO Performance Calculation Methodology

Overview of the Tokyo MOU Changes

On 9 October 2026, the Tokyo Memorandum of Understanding on Port State Control in the Asia-Pacific Region (Tokyo MOU) announced changes to the calculation of flag State and Recognized Organization performance. These performance results are published in the Tokyo MOU Annual Report and used in determining ship risk profiles under the New Inspection Regime (NIR).

The revised method compares each flag State's or RO's detention rate with the regional average detention rate. It also changes the RO attribution terminology and method: the “related RO” will be used for performance calculation instead of the “responsible RO”.

The announcement concerns the methodology for calculating performance and its use in ship selection. It should not be interpreted as a new standalone shipboard convention requirement or as an automatic finding of legal responsibility against an RO.

New Flag State and RO Performance Categories

Under the revised method, performance is determined by comparing the detention rate of an individual flag State or RO with the regional average detention rate.

Illustrative example

If the regional average detention rate were 2%, a rate below 2% would fall into the High category; a rate from 2% up to but not including 4% would be Medium; and a rate of 4% or above would be Low. This example is illustrative only and does not represent the actual Tokyo MOU regional detention rate.

The regional average used for the calculation is therefore important. A performance category should be read against the applicable published regional benchmark and the relevant assessment period.

Assessment Period and Counting of Detentions

As a general rule, the calculation uses data from the latest three calendar years. The Tokyo MOU has specified transitional assessment periods for the initial RO performance calculations.

For operational planning, owners, managers and ROs should distinguish the collection of data from the later publication and application of the resulting performance ratings.

Special Method for Smaller Fleets

The Tokyo MOU has provided a special method for a flag State or RO whose number of inspections during the assessment period is below the critical inspection threshold. The threshold is defined as “100/the regional average detention rate”.

This provision addresses the effect that a small inspection population can have on rate-based comparisons. For a smaller fleet, even one detention can affect the resulting performance category.

“Related RO” Replaces “Responsible RO” for Performance Calculation

A key change is the use of the term “related RO” for RO performance calculation in place of “responsible RO”. The Tokyo MOU states that where a detainable deficiency is related to a statutory certificate, the RO that most recently issued or endorsed that certificate will be identified as the related RO.

The statutory certificate associated with the detainable deficiency is identified using the Tokyo MOU's published Background Table for RO Relation. The Tokyo MOU will continue collecting data on the “responsible RO” for its internal use.

The revised approach makes the traceability of statutory certification records relevant to the performance calculation. Shipowners and technical managers should ensure that certificate records and deficiency documentation are accurate and readily available.

Implementation Timeline

The Tokyo MOU has specified two principal milestones: commencement of collection under the new RO attribution method and later application of the revised performance results to NIR ship selection.

Practical Implications for Shipowners and Technical Managers

The revised method is primarily a flag State and RO performance calculation framework, but it matters to shipowners and technical managers because these performance results contribute to vessel risk profiling under the NIR.

These are prudent compliance practices and are not additional mandatory requirements created by this particular press release. Effective preparation can reduce avoidable deficiencies, but cannot guarantee a particular performance rating or prevent every detention.

Implications for Recognized Organizations

The related-RO methodology places emphasis on identifying the statutory certificate associated with a detainable deficiency and the RO that most recently issued or endorsed it. The Background Table will be used to select the related statutory certificate.

ROs may wish to review their internal processes for statutory certification traceability, survey documentation and analysis of detention trends. They should also ensure that their personnel understand the revised attribution process and its effective dates.

• Maintain accurate statutory certificate issue and endorsement records.
• Review the Tokyo MOU Background Table for RO Relation and applicable instructions.
• Ensure deficiency and certificate information is recorded consistently.
• Monitor published performance results and the applicable assessment periods.

The resulting performance category should be interpreted within the prescribed calculation methodology. It is not, by itself, a complete assessment of an RO's overall technical capability or a determination of causation for an individual deficiency.

Recommended Preparatory Actions Before 2027

Before the revised RO data collection begins, shipowners and technical managers can review their existing PSC compliance arrangements and identify areas requiring attention.

• Review fleet PSC history and detention trends.
• Identify recurring deficiencies and determine their underlying causes.
• Verify the accuracy and status of statutory certificates and endorsements.
• Check maintenance and inspection arrangements for safety-critical equipment.
• Ensure deficiencies are closed out with suitable evidence and verification.
• Review PSC preparation procedures and internal compliance checks.
• Monitor the Tokyo MOU website for the official Background Table and further implementation guidance.

These steps support sound compliance management and inspection readiness. The Tokyo MOU announcement does not prescribe this checklist as a separate mandatory programme.

Conclusion

The Tokyo MOU's revised flag State and RO performance methodology introduces a benchmark based on the regional average detention rate, a specific approach for smaller inspection populations and a new related-RO attribution method for performance calculations.

RO relation data collection begins on 1 January 2027. The first revised results are expected around 1 May 2028 and are scheduled to be applied to NIR ship selection from 1 July 2028.

For shipowners and technical managers, the practical priorities remain effective PSC preparation, reliable statutory certification, robust maintenance, traceable technical records and timely corrective action. These measures help support vessel compliance and reduce avoidable detention risks.