By ShipCalculators.com · Published 25 April 2026 · last updated 6 June 2026

CII Corrective Action Plan: SEEMP Part III

Contents

The CII corrective action plan is the document that a ship of 5,000 GT or above engaged on international voyages must produce when it has been rated D for three consecutive calendar years or E for a single calendar year under MARPOL Annex VI Regulation 28. The CII attained vs required calculator sizes the gap to the C/D boundary the plan must close. The plan is incorporated into the ship’s SEEMP Part III and must show, with year-by-year targets, how the ship will return to at least a C rating. The CII 3-year corrective action plan trigger calculator determines whether the trigger has been met; the CII corrective trajectory calculator then projects the attained CII forward under user-set improvement assumptions to identify the year of expected recovery.

Regulatory foundation

MARPOL Annex VI Chapter 4 and the CII framework

The Carbon Intensity Indicator regime entered MARPOL Annex VI as Chapter 4, inserted by Resolution MEPC.328(76) adopted on 17 June 2021, with effect from 1 November 2022 and operational application beginning 1 January 2023. Regulation 26 of Chapter 4 requires ships to hold a Ship Energy Efficiency Management Plan (SEEMP). Regulation 28 defines the CII rating system and the corrective action obligation.

Regulation 28.1 requires every ship of 5,000 GT or above engaged on international voyages to calculate its attained annual operational CII against a required CII derived from the ship-type reference line and the applicable annual reduction factor. Regulation 28.5 specifies that each ship receives a rating of A, B, C, D, or E based on the ratio of its attained CII to the required CII for that year. Regulation 28.10 then states:

Ships rated D for three consecutive years, or rated E, shall develop a plan of corrective actions to achieve the required CII (rated C, B or A) and incorporate it as part of the SEEMP. The revised SEEMP shall be subject to verification according to paragraph 11 of regulation 26 of this Annex.

The corrective action plan is therefore not a separate compliance certificate. It is an additional section within the SEEMP Part III that exists only when the Regulation 28.10 trigger has been met. MEPC.7/Circ.16, issued on the same date as the entry-into-force of the framework, sets out the structure and content requirements for the plan.

The required CII and the rating boundary mathematics

The attained CII for a ship using fuel oil is calculated as:

\text{CII}_\text{attained} = \frac{\sum_j (FC_j \times CF_j)}{W \times D}

where $FC_j$ is the mass of fuel type $j$ consumed (tonnes) over the calendar year, $CF_j$ is the CO $_2$ conversion factor for that fuel type (g CO $_2$ /g fuel), $W$ is the ship capacity (DWT for bulk carriers, tankers, gas carriers, and combination carriers; lane-metres or number of cars for ro-ro; TEU for container ships), and $D$ is the total distance sailed (nautical miles). The formula and conversion factors are in MEPC.336(76). The CII attained calculator implements this.

The required CII for a given year $Y$ is derived from the ship-type reference line and an annual reduction factor:

\text{CII}_\text{required}(Y) = \text{CII}_\text{ref} \times (1 - Z(Y)/100)

where $\text{CII}_\text{ref}$ is the reference-line CII (from MEPC.337(76), based on the ship’s capacity and type) and $Z(Y)$ is the cumulative reduction factor for year $Y$ relative to 2008. Under MEPC.338(76) and the current framework, the reduction factors run from 5% in 2023 to 11% in 2026. The CII required calculator computes the required CII for any ship type and year.

The A-to-E rating boundary vectors

The five rating bands are defined by four boundary vectors $d_1$ through $d_4$ , which are ship-type-specific and are set out in MEPC.339(76) (superseded by MEPC.348(78) for the post-MEPC 78 framework). The boundaries scale with the required CII for the year:

Boundary	Rating separation	Multiplier
$d_1$	A / B boundary	$\text{CII}_\text{required} \times (1 - \text{sup}_1)$
$d_2$	B / C boundary	$\text{CII}_\text{required} \times (1 - \text{sup}_2)$
$d_3$	C / D boundary	$\text{CII}_\text{required} \times (1 + \text{inf}_1)$
$d_4$	D / E boundary	$\text{CII}_\text{required} \times (1 + \text{inf}_2)$

The superior and inferior multipliers ( $\text{sup}_1, \text{sup}_2, \text{inf}_1, \text{inf}_2$ ) are ship-type-specific constants. For a bulk carrier, the MEPC.348(78) values place the C/D boundary at approximately 1.06 times the required CII and the D/E boundary at approximately 1.18 times, meaning a ship attaining 1.18× or more of the required CII receives an E. A ship between 1.06× and 1.18× receives a D. The CII rating calculator maps any attained/required CII pair to the A-to-E band.

The 2022 Guidelines and MEPC.346(78)

Resolution MEPC.346(78), adopted 10 June 2022, consolidates the SEEMP development guidelines. It specifies that SEEMP Part III must include the target CII for each year, the planned operational measures, the performance self-evaluation methodology, and, where the Regulation 28.10 trigger has been met, the corrective action plan as an additional section. Resolution MEPC.347(78) sets out how Administrations verify CII reporting. Resolution MEPC.348(78) sets out the rating scheme.

The corrective action plan trigger

Three consecutive D ratings

The first time the D-D-D trigger can be met under the current framework is at the end of calendar year 2025, when a ship rated D in 2023, 2024, and 2025 pulls the trigger. The plan must then be incorporated into the SEEMP Part III and submitted for approval during 2026.

The “consecutive” condition resets on any year in which the ship achieves a C, B, or A rating. A ship rated D in 2023, D in 2024, C in 2025, D in 2026, D in 2027, and D in 2028 would not trigger until the end of 2028 (three consecutive D ratings after the 2025 reset). This reset mechanism is intentional: a single year of operational improvement breaks the trigger sequence and removes the obligation, which is why some operators treat a marginal D rating as worth a targeted operational push to avoid formally entering the corrective action process.

A single E rating

The E trigger is more direct. Any ship receiving an E in any calendar year must immediately incorporate a corrective action plan into its SEEMP Part III for the following year. The first possible E trigger was 2023. A ship rated E in 2023 was required to submit a corrective action plan for approval during 2024, with implementation no later than 2025.

The distinction between the triggers matters for the timeline. An E in year $Y$ means the corrective action plan must be in the SEEMP Part III reviewed at the annual SEEMP verification in year $Y+1$ . The D-D-D trigger means the plan must be in the SEEMP Part III reviewed at the annual verification in the year after the third consecutive D.

Scope: which ships are subject

The obligation applies to ships of 5,000 GT and above engaged on international voyages. Regulation 28.6 sets out voyage and ship-type exclusions that reduce the attained CII (the CII voyage adjustment calculator implements these), but the 5,000 GT and international voyage conditions still determine whether a ship is in scope at all. A ship that dips below 5,000 GT (rare for trading vessels) or operates exclusively on domestic voyages is outside the CII framework entirely and cannot be rated or triggered.

Content of the corrective action plan

MEPC.7/Circ.16 defines a six-section structure. Plans that do not follow this structure are typically returned for revision by the reviewing Recognised Organisation.

Section 1: Ship particulars and rating history

The opening section records the IMO number, vessel name, ship type, capacity (DWT or equivalent), year built, flag, and the rating history for the most recent years sufficient to establish the trigger (a minimum of three years for a D-D-D trigger, one year for an E trigger). The trigger condition and trigger year are stated explicitly.

Section 2: Root cause analysis

The root cause analysis is the most technically demanding part of the plan. MEPC.7/Circ.16 requires the analysis to quantify each contributing factor as a percentage of the attained CII or in gCO $_2$ per DWT per nautical mile, to identify the data sources used, and to classify each factor as within the operator’s control, within the charterer’s control, or arising from external factors.

Common structural root causes in D- and E-rated ships include excessive operating speed driven by charter instructions, extended ballast voyages that raise the intensity per tonne-mile (the CII voyage adjustment allows some of these to be excluded under MEPC.333(76)), hull biofouling beyond normal cleaning intervals (a 5% to 12% CII penalty in typical cases), suboptimal trim at prevailing draft conditions, and cargo utilisation shortfalls where the ship operates well below its DWT capacity. Transient factors include ECA compliance fuel switching from HFO to VLSFO or MGO without compensating operational adjustments, and engine performance degradation between scheduled maintenance intervals.

The classification between operator-driven and charterer-driven root causes has direct commercial consequences. Under the BIMCO CII Clause for Time Charters, costs flow to the party responsible for the root cause. A poorly classified root cause analysis can produce a cost-allocation dispute that complicates the implementation of the plan itself.

Section 3: Corrective measures

The corrective measures section lists each planned action with its expected CII improvement and responsible party. MEPC.7/Circ.16 does not mandate any particular measure category; operators choose from operational, technical, and fuel-switching options based on the root cause diagnosis.

Operational measures are available immediately without capital investment. Slow steaming delivers the largest single operational improvement: a 10% speed reduction typically yields an 8% to 15% CII improvement because propulsive power demand scales roughly with the cube of speed (the engine cube-law fuel calculator models this). Just-in-time arrival, coordinated with port operators to eliminate unnecessary steaming at high speed toward a berth that is not available, delivers 2% to 7% on trades with predictable port call windows. Hull cleaning brought to a tighter interval (say 9-monthly instead of 14-monthly) removes the biofouling resistance accumulation that builds after the first 6 to 9 months. Trim optimisation software, now standard on most VLCC and bulk carrier management systems, delivers 1% to 4% through real-time adjustment of ballast distribution.

Technical measures require capital expenditure but produce durable CII improvement that persists regardless of charter party pressure. Energy-saving devices including pre-swirl stators, propeller boss cap fins, Mewis ducts, and kappa fins each deliver 2% to 5% individually and can be stacked. Air lubrication systems on flat-bottomed hulls (bulk carriers, tankers) deliver 5% to 10% under good operating conditions. Engine derating via an Engine Power Limitation or ShaPoLi retrofit, already mandated on many ships for EEXI compliance, reduces the peak power ceiling and often produces a measurable CII improvement when the ship had been operating near its full MCR. Wind-assisted propulsion devices (Flettner rotors, rigid sails) deliver 5% to 15% on routes with favourable wind profiles, though the capital cost and the route-dependency limit their applicability.

Fuel switching is the highest-cost and highest-impact lever. A B30 biofuel blend (30% FAME or HVO by mass, 70% conventional fuel) reduces the carbon intensity of that portion of fuel by approximately 30% for the blended fraction, yielding roughly an 8% to 9% improvement in attained CII if applied continuously across main engine consumption. Full biodiesel (B100) on the main engine reduces the CII contribution of that fuel by 90% to 95%, depending on the lifecycle GHG intensity of the feedstock (computed under the GFI attained calculator framework). Bio-LNG or bio-methanol on dual-fuel ships offer similar order-of-magnitude improvements. The challenge with fuel switching as a corrective measure is cost: biofuel premiums of USD 200 to 600 per tonne over conventional HFO, depending on feedstock, supply region, and contract volume, can make fuel switching economically prohibitive for ships already under commercial pressure from a poor CII rating.

Section 4: Target attained CII trajectory

The trajectory section provides a year-by-year table of target attained CII through the corrective period, set against the required CII for each year and the rating boundaries. The table must show the ship reaching at least a C rating by the final year of the plan. A plan that projects only reaching the D/C boundary in the final year is typically accepted, but one that projects persistent D despite the listed measures will receive a revision request.

The combined effect of multiple simultaneous corrective measures is not simply additive. The standard non-overlapping formula is:

\text{CII}_\text{after} = \text{CII}_\text{before} \times \prod_{i} (1 - s_i)

where $s_i$ is the fractional CII saving from measure $i$ expressed as a decimal. Stacking slow steaming (0.12), hull cleaning (0.05), trim optimisation (0.02), and a B30 biofuel partial switch (0.08) gives:

\text{CII}_\text{after} = \text{CII}_\text{before} \times (1-0.12)(1-0.05)(1-0.02)(1-0.08) \approx \text{CII}_\text{before} \times 0.752

That 24.8% combined reduction is the basis for the trajectory table. The SEEMP combined operational measures calculator implements the non-overlapping formula for a standard set of levers; the CII corrective trajectory calculator uses the resulting combined improvement to project the attained CII year-by-year through the plan period.

Section 5: Self-monitoring procedure

The self-monitoring section specifies how the ship’s management will track implementation. Minimum content per MEPC.7/Circ.16 includes the frequency of internal CII performance reviews (typically quarterly based on the IMO DCS data), the trigger conditions for plan revision (typically a deviation of more than 5% from the target trajectory for two consecutive quarters), and the record-keeping format that the verifying surveyor will inspect at the annual IAPP survey.

Section 6: Approval block

The plan is signed by the master and the operator’s designated person ashore (DPA) and submitted to the flag Administration or its authorised Recognised Organisation. The approval block records the approved status, the approving authority, and the approval date.

Verification and the SEEMP Part III audit

Annual IAPP survey

The corrective action plan is verified annually through the SEEMP Part III verification that forms part of the annual survey under MARPOL Annex VI Regulation 5. The surveyor confirms that the plan is present in the SEEMP Part III, that the corrective measures listed are demonstrably being implemented (fuel purchase records for biofuel, propulsion log data for slow steaming, hull cleaning records, trim management logs), and that the actual attained CII for the completed year is within the tolerance band of the target trajectory.

A deviation that falls outside the tolerance results in a plan revision requirement noted in the survey report. The revised plan must be submitted within the agreed period (typically 3 months) and approved before the next annual survey.

IEE Certificate annotation

The International Energy Efficiency (IEE) Certificate, issued under MARPOL Annex VI Regulation 6 and maintained by the SEEMP Part III under Regulation 26, carries the CII rating for each year and the corrective action plan approval status. Port state control inspectors check this certificate. A ship for which the corrective action plan approval box is blank or showing a deficiency will face a PSC deficiency notice; a ship that continues operating without an approved plan after the annual survey deadline risks detention.

Port state control

Port state control officers in Paris MOU, Tokyo MOU, and United States Coast Guard (USCG) ports have included CII plan status checks in their expanded inspection protocols since 2024. The verification step is documentary at present: the inspector confirms that the SEEMP Part III incorporates an approved corrective action plan with a valid approval stamp and that the IEE Certificate annotation matches. Expanded PSC guidance is expected as the regime matures and the 2026 review makes any rule changes final.

Integration with SEEMP Part III

The SEEMP Part III is the primary CII operational planning document required of every in-scope ship under MARPOL Annex VI Regulation 26. It sets the annual target CII, the planned operational measures, and the self-evaluation procedure for every calendar year. Where the ship is not in corrective action, Part III is the only CII planning document.

When the Regulation 28.10 trigger fires, the corrective action plan is added as a supplementary section within Part III. It does not replace the standard Part III planning content; it supplements it with the additional burden of root cause analysis, the specific corrective measure catalogue, the trajectory table, and the plan approval status.

The corrective action plan remains in force until the ship achieves a C rating (or better) for at least one full calendar year. At that point the plan is administratively closed in the SEEMP Part III, and the ship reverts to the standard Part III planning cycle. The SEEMP Part III / Regulation 26 calculator covers the standard planning cycle structure.

Revision during the plan period

If the ship falls below its trajectory target in a plan year (attained CII exceeds the target by more than the accepted tolerance), the operator must revise the plan with additional measures. The revision triggers a fresh approval cycle with the Recognised Organisation. In practice, most revision requests arise from one of three causes: the claimed savings for a measure were overstated at plan inception (optimistic biofuel availability, hull cleaning schedule not maintained, slow steaming instructions overridden by charterer), the required CII moved more steeply than anticipated (because the annual reduction factor schedule continues tightening), or an unplanned operational event (extended off-hire, dry-docking displaced to a different year) disrupted the trajectory.

Charter-party considerations and the BIMCO CII Clause

The principal-agent problem in CII compliance

The CII rating is calculated on the ship’s total annual fuel consumption divided by total cargo capacity and total distance sailed. The ship owner holds the MARPOL compliance obligation and faces the corrective action plan requirement. But the variables that drive attained CII on a time-chartered ship (operating speed, cargo loading, voyage routing, port stay durations) are largely within the charterer’s control.

This creates a direct tension. A charterer who instructs higher speeds to meet commercial commitments, or who books the ship on ballast-heavy routes, can push the attained CII above the D/E boundaries while the owner bears the regulatory consequence.

BIMCO CII Clause for Time Charters (November 2022)

The BIMCO CII Clause for Time Charters, published in November 2022, addresses this allocation. Key provisions include:

The charterer must issue voyage instructions consistent with achieving a CII rating of C or better, where it is reasonably practicable to do so.
The owner may modify voyage instructions (including reducing speed) to the extent necessary to maintain compliance with the CII target.
Where corrective measures are required, costs are allocated between owner and charterer based on whether the measure responds to an owner-controlled root cause (hull, propulsion, engine) or a charterer-controlled root cause (speed, routing, cargo loading).
The clause includes a specific procedure for the case where the ship enters the corrective action plan period: the charterer must cooperate with the owner’s corrective action obligations and may not instruct operations that would demonstrably prevent the ship from meeting the plan trajectory.

The BIMCO clause is the industry standard template, but it is not mandatory. Ships on legacy charters that predate the CII regime, or on short-term voyages charters without the BIMCO CII language, may have no contractual mechanism to pass compliance costs or to enforce speed restrictions against a charterer’s commercial instructions.

Cost allocation in the corrective action plan

The root cause classification in Section 2 of the plan directly feeds the cost allocation under the BIMCO clause. Costs associated with charterer-driven root causes (slow steaming implementation, JIT arrival coordination, biofuel premium for fuel switched on charterer-directed voyages) are typically charterer’s account under the clause. Costs for owner-driven measures (hull cleaning, ESD retrofit, engine derating) fall to the owner. Weather routing services are typically split based on the benefit attribution.

Disputes about cost allocation are the most common commercial complication in corrective action plan implementation. The allocation table in the BIMCO clause provides a starting framework but is not self-executing; owners and charterers typically negotiate cost-sharing on a plan-specific basis against the clause’s underlying principles.

Rating bands and corrective action thresholds

The following table shows the rating band thresholds for a generic bulk carrier using illustrative MEPC.348(78) boundary multipliers and a Required CII of 5.00 gCO $_2$ /DWT·nm. The multipliers are ship-type-specific; the CII rating calculator applies the correct ship-type multipliers from MEPC.348(78).

Rating	Attained CII range (illustrative bulk carrier)	Boundary description
A	Below $d_1$ : below 0.86 × Required	Superior efficiency; no CII obligation beyond standard reporting
B	$d_1$ to $d_2$ : 0.86× to 0.94× Required	Above average; no corrective obligation
C	$d_2$ to $d_3$ : 0.94× to 1.06× Required	Acceptable; required rating to exit corrective action
D	$d_3$ to $d_4$ : 1.06× to 1.18× Required	Below target; three consecutive D years trigger the plan
E	Above $d_4$ : above 1.18× Required	Significantly below target; one E year immediately triggers the plan

For the illustrative ship with Required CII = 5.00 gCO $_2$ /DWT·nm, the A/B boundary is at 4.30, B/C at 4.70, C/D at 5.30, and D/E at 5.90. A ship attaining 6.10 is firmly in E territory. The actual multipliers vary by ship type and are published in the annex to MEPC.348(78).

Worked example: a Handymax bulk carrier

A 45,000 DWT Handymax bulk carrier has the following CII rating history:

Year	Attained CII (g CO $_2$ /DWT·nm)	Required CII	Ratio	Rating
2023	5.85	5.25	1.114×	D
2024	5.92	5.14	1.152×	D
2025	6.08	5.03	1.209×	E

The E rating in 2025 immediately triggers the Regulation 28.10 obligation (the D-D trigger is redundant once E is reached). The corrective action plan must be incorporated into the SEEMP Part III and submitted for approval by mid-2026.

Root cause analysis identifies three contributing factors: average operating speed 0.5 knots above the fuel-optimum speed profile (quantified at +9% CII penalty); hull cleaning deferred 5 months beyond the 12-month schedule (quantified at +6% CII penalty); and cargo utilisation averaging 87% of DWT on laden legs (quantified at +4% CII penalty, because the CII denominator uses full DWT regardless of actual load).

The corrective measures for the plan period 2026 to 2028:

Measure	Fractional improvement $s_i$	Implementation
Speed reduction to fuel-optimum + EPL retrofit	0.10	1 January 2027
Hull cleaning every 10 months (vs. 17-month actual)	0.06	Next port call after approval
Trim optimisation software upgrade	0.02	1 March 2027
B20 biofuel blend on main engine	0.06	From 1 July 2027

Combined saving for year 2027 and beyond:

1 - (1-0.10)(1-0.06)(1-0.02)(1-0.06) = 1 - (0.90)(0.94)(0.98)(0.94) \approx 1 - 0.778 = 0.222

That is a 22.2% reduction in attained CII from the 2025 base.

Target trajectory:

Year	Attained CII target	Required CII	Ratio	Projected rating
2026	6.08 (no full-year measures yet)	4.92	1.235×	E (plan year 0)
2027	$6.08 \times 0.778 = 4.73$	4.82	0.981×	C
2028	4.73 (steady-state, measures mature)	4.72	1.002×	C

The plan returns the ship to C by 2027. The 2028 result is marginal (just inside C); the plan notes that biofuel supply volume will be reviewed in late 2027 to confirm continued B20 availability. The CII corrective trajectory calculator and the SEEMP Part III plan calculator implement this calculation structure for arbitrary inputs.

The 2026 review

Resolution MEPC.328(76) included a mandatory commitment (paragraph 5 of the Resolution) for the IMO to review the effectiveness of the CII measures before 1 January 2026. That review was formally initiated at MEPC 80 in 2023. The review scope, as set out in the MEPC 80 outcome document, covers: the appropriateness of the annual reduction factors (whether the 5% to 11% schedule through 2026 should be extended or steepened for 2027 onwards), the DWT capacity metric (whether capacity should be based on actual cargo carried rather than rated DWT, which would remove the perverse incentive to sail partly laden), the set of voyage exclusions and adjustments available to operators, and the potential for tighter verification requirements or financial consequences for ships that persistently fail to meet their corrective action plan trajectories.

As of MEPC 83 (April 2025), the review remained open on the key contested points. The reduction factors for 2027 onward have not been finalised. IMO member states have filed positions ranging from extending the existing taper to accelerating to 20% cumulative reduction by 2030. The DWT vs. cargo-carried metric question is the most structurally significant: switching to actual cargo carried would fundamentally change the CII calculation for vessels in variable-capacity trades, but it would also require real-time cargo-weight reporting that is not currently part of the IMO DCS system. The 2026 review outcome is expected to be implemented via a new MEPC resolution replacing or amending MEPC.338(76).

Limitations of the CII corrective action mechanism

The corrective action plan mechanism has drawn documented criticism from regulators, class societies, and independent researchers. These are not theoretical objections; they reflect structural features of the regulation that produce measurable anomalies.

No direct financial penalty. A ship rated D or E faces no immediate financial consequence under MARPOL Annex VI. The only obligation is to produce a document and have it approved. This is in contrast to the EU ETS for shipping, which imposes a direct allowance surrender cost for every tonne of CO $_2$ emitted above the allowance threshold, and FuelEU Maritime, which imposes a per-GJ penalty for fuel intensity above the GHG target. The ICCT’s analysis of the 2023 corrective action plan cohort found that a material fraction of plans projected trajectories that, at the claimed measure savings, would not in fact reach C by the plan end date. Without a financial backstop, the incentive to submit a realistic plan is limited.

The DWT denominator perverse incentive. The CII denominator uses rated DWT (or equivalent capacity) regardless of actual cargo loaded. A ship that carries 70% of its DWT on laden legs has the same denominator as one carrying 95%. This means a ship can improve its attained CII by refusing lighter cargo loads, concentrating on full-load voyages, or even by increasing its rated DWT through structural modifications that add deadweight without adding propulsive power. The correction runs in the opposite direction to the intended environmental outcome: if a ship declines lower-utilisation voyages to protect its CII rating, the same cargo may be moved on an additional (or larger) ship, increasing total fleet emissions. The 2026 review is examining whether actual transport work (tonnes of cargo times nautical miles) should replace rated capacity in the denominator.

Ballast voyage treatment. Ballast voyages consume fuel and generate CO $_2$ but carry no cargo, making the CII for a ballast leg appear extremely poor (attained CII is high relative to required because the denominator is unchanged DWT while the numerator accumulates fuel). The CII voyage adjustment mechanism under MEPC.333(76) allows certain voyage types to be excluded (ice-class operations, certain port services, certain cargo-specific conditions), but it does not provide a blanket ballast-voyage adjustment. Ships on routes with structurally high ballast ratios, including certain trampers and tankers returning empty from discharge ports, carry a structural CII disadvantage not captured by the correction mechanism.

Short-horizon planning. The corrective action plan must show return to C rating within the plan period, but the plan’s trajectory projections are inherently model-dependent. Fuel price changes, charter market movements, or post-2026 reduction factor steepening can invalidate a plan’s assumptions within months of approval. The annual revision cycle helps, but the 12-month lag between the end of the reporting year and the submission of a revised plan means a ship can be one to two years behind in responding to changed conditions.

Verification depth. The annual survey verification confirms that measures are being implemented (records exist, signatures are present), but it does not independently audit the attained CII calculation. The IMO DCS data from which the attained CII is calculated has known quality issues, including fuel consumption reporting gaps, voyage distance discrepancies between noon reports and AIS data, and capacity misreporting on older vessels. Until IMO DCS data quality improves, the attained CII for a given ship in a given year carries a level of uncertainty that the corrective action plan framework does not formally address.

Interaction with the IMO Net-Zero Framework and EU measures

The IMO Net-Zero Framework (Chapter 4 ter of MARPOL Annex VI, targeted for entry into force in 2027) introduces a financial mechanism based on a Greenhouse Gas Fuel Intensity (GFI) target for ships. Ships exceeding the GFI target will be required to purchase Remediation Units at a price that reflects the cost gap between their fuel mix and the target mix. The GFI attained calculator and GFI compliance calculator implement this framework.

A ship in CII corrective action is very likely also to be in deficit under the Net-Zero Framework GFI metric, since both metrics track operational fuel efficiency per unit of transport work. The corrective measures that improve CII (fuel switching to lower-carbon fuels, speed reduction, energy-saving devices) will simultaneously reduce GFI intensity. After 2027, operators managing a corrective action plan will be doing so against two parallel regulatory clocks: the CII rating trajectory and the GFI financial mechanism.

The EU ETS for shipping (mandatory from January 2024 for large ships on EU routes) and FuelEU Maritime (from January 2025) add further parallel pressures. Ships in corrective action on the CII metric are almost certain to be incurring elevated EU ETS costs and FuelEU penalties simultaneously. The operational measures in the corrective action plan will reduce all three metric burdens in parallel, which is why operators preparing corrective action plans are increasingly framing them as integrated multi-regulatory compliance plans rather than single-regulation documents.

Frequently asked questions

What triggers a CII corrective action plan?

A ship of 5,000 GT or above on international voyages must develop a corrective action plan when it is rated D for three consecutive calendar years or rated E for any single calendar year, per MARPOL Annex VI Regulation 28.10.

Where is the corrective action plan kept?

The plan is incorporated into the ship's SEEMP Part III. It is not a standalone document; it supplements the standing operational CII plan with additional measures until the ship returns to a C rating.

Who approves the corrective action plan?

The flag Administration or its delegated Recognised Organisation (typically the ship's classification society) approves the plan. Approval must be completed before the next annual IAPP survey.

What does the plan have to show?

Per MEPC.7/Circ.16, the plan must include a root cause analysis, specific corrective measures with expected CII improvements, a year-by-year target attained CII trajectory showing return to a C rating, an implementation timeline, and a self-monitoring procedure.

What happens if a ship does not produce a corrective action plan?

Port state control inspectors check for plan approval status on the IEE Certificate. A ship subject to the requirement that lacks an approved plan faces a deficiency and can be detained until the deficiency is remedied.

What is the 2026 CII framework review?

IMO Resolution MEPC.328(76) required the IMO to complete a comprehensive review of the CII framework before 1 January 2026. That review was initiated at MEPC 80 and covers reduction factors, the DWT capacity metric, voyage adjustments, and the potential for financial consequences for non-compliance.