Regulation · 7 min read

CII in 2026–2027: the tightening, the correction factors and what a C, D or E rating costs you

The CII reduction factor jumps to 13.625% in 2027 and 21.5% by 2030. How the bands move, which corrections apply and what a D really costs.

The Naavra regulatory desk · 2026-09-24 · 1,632 words · 7 min read

The Carbon Intensity Indicator has been part of every large ship's year since 2023. Until now the required line fell by two points a year, and most fleets absorbed that with normal operational care. From 2027 the pace changes. The IMO's Marine Environment Protection Committee adopted the 2027–2030 reduction factors in resolution MEPC.400(83) in April 2025: 13.625% for 2027, 16.25% for 2028, 18.875% for 2029 and 21.5% for 2030, all against each ship type's 2019 reference line. The step is now 2.625 points a year.

That sounds small. For a ship sitting near a rating boundary it is the difference between a C and a D, with nothing changed on board. This article explains how the rating is built, why the boundaries move, which correction factors you may apply, what a poor rating costs in practice, and how to plan a rating a year ahead rather than read it in the spring.

How the rating is built

A ship's attained CII is its annual CO2 divided by its capacity multiplied by the distance sailed. For most cargo ships the unit is grams of CO2 per deadweight tonne-mile; for cruise ships and ro-ro passenger ships capacity is gross tonnage. Fuel becomes CO2 through fixed conversion factors: about 3.114 tonnes of CO2 per tonne of heavy fuel oil, 3.206 for marine diesel and gas oil, and 2.750 for LNG.

The required CII is the 2019 reference line for the ship's type and size (guidelines G2, MEPC.353(78)), reduced by that year's factor. The rating comes from where the attained figure sits against four boundaries drawn around the required line.

Why the bands move with the line

The four boundaries are not fixed numbers. They are ratios of the required line, called dd-vectors in the rating guidelines (G4, MEPC.354(78)). For a bulk carrier they are 0.86, 0.94, 1.06 and 1.18. For a tanker they are 0.82, 0.93, 1.08 and 1.28. For a container ship, 0.83, 0.94, 1.07 and 1.19. A bulk carrier whose attained CII is more than 1.06 times its required figure is a D; above 1.18 it is an E.

Because the boundaries are ratios, every boundary falls when the required line falls. A ship that operates exactly as before drifts upwards through the bands.

A worked illustration

Illustration: a synthetic bulk carrier whose attained CII stays flat at 90% of its 2019 reference line every year.

Nothing changes on board, yet the ship is a D from 2028. Three consecutive Ds (2028, 2029, 2030) trigger a corrective action plan. To stay a C in 2028 the ship needs to cut its attained figure by about 1.4%; to stay a C in 2030, by about 7.5%. That is the real shape of the tightening: small in any one year, large over four.

The correction factors, and what they are for

Some ships burn fuel for reasons that have little to do with carrying cargo efficiently. The interim guidelines on correction factors and voyage adjustments (G5, MEPC.355(78)) allow defined deductions so that a ship is not marked down for that fuel. They include:

• Ice class and distance sailed in ice, where the ship's design and the route make it unavoidable.
• Ship-to-ship transfer and shuttle tanker operations, including shuttle tankers on dynamic positioning, which may apply a specific correction instead of the individual deductions.
• Fuel used for cargo cooling on gas carriers, and certain electrical and boiler consumption, such as power for discharge pumps on tankers.

Three practical points follow. First, a correction must be evidenced: separate metering or a documented method, recorded when the fuel is burned. Second, the corrections apply to the attained figure reported in the Data Collection System, so the verifier sees them. Third, corrections are not a strategy. They remove fuel that should never have counted; they do not buy margin.

From 1 January 2027 a further clarification applies. The IMO's revised interim guidance on biofuels (MEPC.1/Circ.905/Rev.1), approved at MEPC 84 in 2026, says the carbon factor of a biofuel blend is weighted by mass rather than by energy. If you plan to use blends to protect a rating, run the numbers on the 2027 method.

What a C, D or E rating costs you

No public figure puts a price on a D, and anyone quoting one is guessing. What can be counted is where the cost lands.

The time charter clause

Most of the levers sit with whoever directs the ship. That is why BIMCO published its CII Operations Clause for Time Charter Parties in 2022: it sets out how owners and time charterers share data and cooperate on the ship's carbon intensity during the charter. If your time charters do not deal with CII, the owner carries the rating while the charterer controls the speed and the waiting time.

The cost of the fix

The fix for a D is usually operational, and it usually costs days. As a rule of thumb, fuel per mile rises roughly with the square of speed, so the 7.5% cut in the 2030 illustration above needs something like a 4% slower average speed on the same trade, or the equivalent in less waiting, cleaner hulls or better fuel. Slower speed means more days per voyage. That is the cost to price, voyage by voyage, before the fixture is made.

What moves a rating, and by how much

A rating moves when either side of the ratio moves. Emissions fall when a ship burns less fuel, or lower-carbon fuel, for the same work. Transport work rises when she sails further with the same capacity.

Waiting is often the largest single lever. A ship drifting at anchor for three days burns fuel for zero distance, which is the worst possible trade for the indicator. Agreeing arrival times with ports and charterers is a CII measure as much as a courtesy.

The data behind the number

The attained CII is only as good as the fuel and distance behind it. Fuel data goes to the administration or recognised organisation within three months of the year's end, and the Statement of Compliance, with the rating, follows by the end of May. Mistakes found by the ship in March are easy to fix. Mistakes found by a verifier become the official figure.

• Reconcile consumption against bunker delivery notes and remaining-on-board figures at every voyage end.
• Check that distance is the distance actually sailed, not the planned route.
• Record periods that the correction guidelines treat separately, with evidence, when they happen.

What is still under review

MEPC 84 in 2026 began the second phase of the review of the CII and SEEMP frameworks, to be completed in 2028. It did not adopt amendments to the metric; proposals such as a different metric for cruise ships were discussed but not agreed. Work on a strengthened SEEMP, with internal reviews and implementation logs, is due at MEPC 86 in October 2027. The 2027–2030 factors are adopted and stand. Plan on them.

What to do Monday

• Pull each ship's 2026 year-to-date attained CII and project the full year from fixed voyages, not only sailed ones.
• Re-run each projection with the 2027 factor (13.625%) and flag every ship within 5% of a boundary.
• For each flagged ship, name the lever (speed, waiting, hull, fuel) and the person who owns it.
• Check every time charter for a CII clause; list those without one before the next renewal.
• Confirm that correction-factor fuel (cargo cooling, discharge pumps, ice) is metered and recorded now, not reconstructed in January.
• If you plan biofuel blends for 2027, recalculate their effect with the mass-weighted carbon factor.
• Put the carbon cost, CII and EU ETS, into every voyage estimate from this week.

Questions and answers

Topics

This article explains; it is not legal or regulatory advice. Check the instrument in force for your ship.