ACT-KA-000202 · Rev. 1 · IMO CII
IMO rating bands for CII
IMO CII ratings are expressed as A, B, C, D or E. A means major superior performance, B means minor superior performance, C means moderate performance, D means minor inferior performance and E means inferior performance. The rating is based on how the ship's attained annual CII compares with the required annual CII and rating boundaries.
The practical target is normally to maintain C or better. A D rating for three consecutive years or one E rating requires a corrective action plan showing how the vessel will return to C or better.
Difficulty: BeginnerReviewed: 2026-07-24
IMO CII rating bandsCII A B C D ECII corrective action planSEEMP Part III
Frequently Asked Questions
Is C rating a failure?
No. C is the moderate or compliant performance level. The vessel should still monitor margin because the required CII becomes progressively stricter over time.
Which ratings need management attention?
D and E need immediate attention. A vessel trending from B to C may also need attention because small reporting or operational changes can push the vessel into D.
Can a ship move from D to C within the year?
Yes, if remaining voyages, fuel use, speed profile, routeing and operating pattern improve enough before the annual result is finalized.
Are rating thresholds identical for all ship types?
No. Reference lines and parameters vary by ship type and size. The vessel-specific CII configuration must be correct before interpreting the rating.
Technical Explanation
The rating band is not a fixed fuel consumption number. It is a vessel-specific comparison. The required CII is calculated from reference line values and the annual reduction factor. Rating boundaries are then applied around the required value.
Lower attained CII is better. Therefore, a vessel with attained CII well below the required CII can receive A or B. A vessel close to the required value may receive C. If attained CII is above the rating boundary, D or E may result.
Step-by-Step Procedures
1. Calculate annual attained CII.
2. Calculate annual required CII for the vessel type, capacity and year.
3. Apply the IMO rating boundary factors.
4. Assign A, B, C, D or E.
5. Record the result in the annual evidence pack.
6. Trigger SEEMP action workflow if D/E risk exists.
Checklists
• Correct ship type selected
• Correct capacity basis selected
• Reporting year reduction factor applied
• Annual fuel and distance locked after verification
• Rating boundary logic reviewed
• D/E alerts reviewed by superintendent
Practical Case Studies
A vessel may have an attained CII of 4.85. Whether that is good or bad depends on its required CII. If the required CII is 5.20, the vessel is better than required. If the required CII is 4.50, the same attained value is worse than required.
KPI Monitoring
• Current rating forecast
• Margin to C rating boundary
• Number of months in D/E trend
• Vessels with action plan required
• A/B vessels eligible for incentive or chartering advantage
Formula
Rating basis = attained annual CII compared with required annual CII and IMO rating boundaries.
If attained CII is lower than required CII, performance is better.
If attained CII is higher than required CII, performance is worse.
Related Actinium-SM Modules
• A-E rating gauge
• Rating trend chart
• Fleet rating comparison
• Early D/E warning
• Corrective action workflow
- A-E rating gauge
- Rating trend chart
- Fleet rating comparison
- Early D/E warning
- Corrective action workflow
ComplianceReports & AnalyticsDaily Reports
Videos and Diagrams
• Rating band graph: attained CII plotted against A, B, C, D and E thresholds.
References
• IMO CII rating guidance and IMO EEXI/CII FAQ.
• IMO GreenVoyage2050 worked example material on deriving rating bands.
Use Actinium-SM to monitor CII rating margin before the year closes.
Turn encyclopedia knowledge into executed jobs, evidence, and audit-ready records.
Last review: 2026-07-24