The Paris Memorandum on Port State Control (Paris MoU) will revise its calculation methodologies for Recognized Organization (RO) performance, in a manner consistent with flag State performance. The effective date of implementation, 6 July 2027, synchronizes with the entry into effect of the amended EU Port State Control Directive.

Decisions made to revise the approach to RO performance include:

Revised calculation methodology
The current RO Performance calculations are probabilistic, utilizing a binomial approach, while the new system will be deterministic.

Under the new methodology, an RO’s average detention rate over a given period (typically three years) will be assessed against the overall average detention rate. Their categorisation will be determined as follows:
 

• High Performance: The detention rate is better than the overall average.
• Medium Performance: The detention rate is equal to or worse than the overall average.
• Low Performance: The detention rate is at least twice the overall detention average.

To underscore that the performance list's sole purpose is to feed into the Ship Risk Profile for targeting ships, and not to rank ROs within categories, ROs will be listed alphabetically per list.

From RO responsibility to RO relation
Instead of manually assigning 'RO responsibility’ by a PSCO for each detainable deficiency the new methodology will connect a detainable deficiency to the RO that issued or endorsed the relevant statutory certificate.

The process will change: PSCOs will, under the new methodology, select the statutory certificate to which the detainable deficiency pertains, guided by the Information System.

Multiple detainable deficiencies from a single detention related to the same RO will be counted as one detention.

Procedural steps and transitional period
In order to be able to implement the new approach on 6 July 2027, the linking of detainable deficiencies to statutory certificates issued or endorsed by ROs will commence on 1 January 2026. The new methodology will then be implemented on 6 July 2027, using one calendar year (2026) of data, increasing to two calendar years of data (2026 and 2027) on 1 July 2028, and finally incorporating three full calendar years of data from 1 July 2029.

The background table, clarifying the relationship between detainable deficiencies and statutory certificates, will be made available on the Paris MoU website well before the new system's implementation on 6 July 2027.​​​​​​​

​​​​​​​Limited number of inspections
All ROs will be included in the performance list, regardless of their inspection volume, to ensure their categorisation can be utilized in the Paris MoU Ship Risk Profile. For ROs with a limited number of inspections, their performance will be calculated using distinct criteria ensuring that a single detention will not immediately place them on the low perfomance list.