Mariners Digest
CII rating in 2026: reduction factor, A–E boundaries and corrective action plans
Every ship of 5,000 GT and above gets a yearly IMO carbon intensity rating from A to E. For 2026 the required CII is 11% below the 2019 reference line, rising to 21.5% by 2030. A ship rated D three years in a row, or E once, needs a plan of corrective actions in its SEEMP. The CII rules are under review until 2028.
Reduction factors, 2023 to 2030
The required CII of a ship is its 2019 reference line cut by the factor (Z) for the year. The 2027–2030 values were added by resolution MEPC.400(83), adopted on 11 April 2025.
| Year | Reduction vs 2019 reference line |
|---|---|
| 2023 | 5% |
| 2024 | 7% |
| 2025 | 9% |
| 2026 | 11% |
| 2027 | 13.625% |
| 2028 | 16.25% |
| 2029 | 18.875% |
| 2030 | 21.5% |
Source: IMO, resolution MEPC.400(83), amendments to the CII reduction factor guidelines (G3), Table 1; read on 13 November 2026.
How the A–E boundaries work
- Four boundaries: superior, lower, upper and inferior. Each is the ship’s required CII for the year multiplied by a ship-type factor, exp(d1) to exp(d4) (G4).
- The rating: below the superior boundary is A; between superior and lower is B; between lower and upper is C; between upper and inferior is D; above the inferior boundary is E (G4).
- Where the factors come from: the 2019 fleet data, set so that the middle 30% of ships rated C, the next 20% either side B or D, and the outer 15% A or E (G4).
- They tighten each year with the required CII; the relative distance between the boundaries stays the same (G4).
- Worked example from the guidelines: a bulk carrier with a required CII of 10 gCO2/(dwt·nmile) has boundaries of 8.6, 9.4, 10.6 and 11.8; an attained CII of 9 is rated B.
Boundary factors by ship type
Multiply the ship’s required CII by these factors to get its four boundaries.
| Ship type | A | B exp(d1) | B | C exp(d2) | C | D exp(d3) | D | E exp(d4) |
|---|---|---|---|---|
| Bulk carrier | 0.86 | 0.94 | 1.06 | 1.18 |
| Gas carrier, 65,000 DWT and above | 0.81 | 0.91 | 1.12 | 1.44 |
| Gas carrier, under 65,000 DWT | 0.85 | 0.95 | 1.06 | 1.25 |
| Tanker | 0.82 | 0.93 | 1.08 | 1.28 |
| Container ship | 0.83 | 0.94 | 1.07 | 1.19 |
| General cargo ship | 0.83 | 0.94 | 1.06 | 1.19 |
| Refrigerated cargo carrier | 0.78 | 0.91 | 1.07 | 1.20 |
| Combination carrier | 0.87 | 0.96 | 1.06 | 1.14 |
| LNG carrier, 100,000 DWT and above | 0.89 | 0.98 | 1.06 | 1.13 |
| LNG carrier, under 100,000 DWT | 0.78 | 0.92 | 1.10 | 1.37 |
| Ro-ro cargo ship (vehicle carrier) | 0.86 | 0.94 | 1.06 | 1.16 |
| Ro-ro cargo ship | 0.76 | 0.89 | 1.08 | 1.27 |
| Ro-ro passenger ship | 0.76 | 0.92 | 1.14 | 1.30 |
| Cruise passenger ship | 0.87 | 0.95 | 1.06 | 1.16 |
Source: IMO, resolution MEPC.354(78), 2022 CII rating guidelines (G4), Table 1 and section 3; read on 13 November 2026. Capacity in the CII is DWT for the cargo ship types and GT for ro-ro and cruise ships (G4, Table 1).
Corrective action plans
- Trigger: a ship rated D for three consecutive years, or rated E in any year, must develop a “plan of corrective actions” (IMO).
- Where it goes: the SEEMP is reviewed to include the plan, and the revised SEEMP goes to the Administration (or the organization it authorizes) for verification, preferably with the CII report and no later than one month after it (MARPOL Annex VI regulation 28.8).
- Then: the ship must carry out the planned corrective actions (regulation 28.9).
- The other end: Administrations, port authorities and others are encouraged to give incentives to ships rated A or B (regulation 28.10).
- Data: the attained CII comes from the fuel consumption data reported to the IMO Data Collection System (IMO).
Sources: IMO, “Improving the energy efficiency of ships”, and regulation 28.7–28.10 of MARPOL Annex VI as reproduced in IMO Circular Letter No.5005; read on 13 November 2026.
Status of the IMO review
- Required by the rules: MARPOL Annex VI regulation 28.11 asked IMO to complete a review of the CII regulations by 1 January 2026 (MEPC.400(83)).
- Phase 1 done: MEPC 83 (April 2025) finalized phase 1 of the review and set the 2027–2030 factors (IMO).
- Phase 2 now: planned from spring 2026 to spring 2028, covering the SEEMP framework, further CII metrics and alignment with the IMO Net-Zero Framework (IMO).
- What it means today: no change to the rating method has been adopted; the factors and boundaries above apply to 2026. IMO’s environment committee meets again at MEPC 85, 30 November to 3 December 2026.
Sources: IMO, MEPC 83 meeting summary and “Cutting GHG emissions from ships”; read on 13 November 2026. The longer-term fuel rules are explained in IMO Net-Zero Framework: where it stands.
Questions
What is the CII reduction factor for 2026?
11% below the 2019 reference line. It follows 5% (2023), 7% (2024) and 9% (2025). The factors for 2027 to 2030 were set by IMO resolution MEPC.400(83) in April 2025: 13.625%, 16.25%, 18.875% and 21.5%.
Which ships need a CII rating?
IMO says the CII is mandatory for ships of 5,000 gross tonnage and above. The rules entered into force on 1 January 2023, and each ship gets a rating every year from its attained CII, worked out from the fuel consumption data it reports to the IMO Data Collection System.
How are the A to E rating boundaries set?
Under IMO's CII rating guidelines (G4), four boundaries are found by multiplying the ship's required CII by four ship-type factors, exp(d1) to exp(d4). For a bulk carrier these are 0.86, 0.94, 1.06 and 1.18, so a required CII of 10 gives boundaries of 8.6, 9.4, 10.6 and 11.8; an attained CII of 9 is a B.
When does a ship need a corrective action plan?
IMO says a ship rated D for three consecutive years, or rated E, must develop a plan of corrective actions. Under MARPOL Annex VI regulation 28.8 the ship's SEEMP (Ship Energy Efficiency Management Plan) is revised to include it and submitted for verification no later than one month after the CII is reported.
Do the rating bands get harder each year?
The boundaries move with the required CII. Because the reduction factor rises each year, the required CII falls, and the four boundaries fall with it; the relative distance between them does not change (G4 guidelines).
Is the CII being changed?
It is under review. IMO finished phase 1 of the review of the short-term measure at MEPC 83 in April 2025. Phase 2 is planned from spring 2026 to spring 2028 and covers the SEEMP framework, further CII metrics and alignment with the Net-Zero Framework. Until IMO adopts changes, the current rules apply.
Mariners Digest is made by CryoSim. It is not affiliated with or endorsed by IMO. This page summarises IMO’s published documents in CryoSim’s own words and is not legal advice; MARPOL Annex VI and the IMO guidelines always take precedence. Published 2026-11-13, updated 2026-11-13. See also IMO MEPC 85: what to watch, FuelEU Maritime in 2026, EU ETS for shipping in 2026 and Mariners Digest.
