Shipping Decarbonisation Rules: IMO Targets, CII, EEXI, EU ETS and FuelEU Explained

Shipping now answers to two sets of climate rules. The IMO sets global ones: the 2023 strategy aims for net-zero emissions from international shipping by or around 2050, and the EEXI and CII measures already rate every large ship. The European Union adds its own: since 2024 ships pay for their emissions under the EU Emissions Trading System, and since 2025 FuelEU Maritime limits the greenhouse-gas intensity of the energy they use.

The IMO's planned global fuel standard and carbon price, the Net-Zero Framework, was approved in 2025 but its adoption was postponed for a year. This page sets out what each rule requires, when, and what it means on board.

Rules and dates as of October 2026. Check your flag state and classification society for the latest circulars before acting on any date.

The rules at a glance

The IMO's targets

The IMO revised its greenhouse-gas strategy in July 2023. It replaced the 2018 aim of halving emissions by 2050 with a goal of net zero by or around 2050, and added two checkpoints measured against 2008: a cut of at least 20%, striving for 30%, by 2030, and at least 70%, striving for 80%, by 2040.

It also set a 2030 target for zero or near-zero emission fuels, energy sources and technologies to provide at least 5%, striving for 10%, of the energy shipping uses.

These are targets for the sector, not rules for individual ships. The rules that bite on a particular ship are the measures below.

EEXI: the design standard

The Energy Efficiency Existing Ship Index applies the efficiency standard for new ships (EEDI) to the existing fleet. It is assessed once, against the ship's design. Ships that fall short most often install an engine or shaft power limitation, which caps the power available in normal service, or improve efficiency with technical upgrades. For how the index is calculated and the options for compliance, see our EEXI guide.

CII: the yearly rating

The Carbon Intensity Indicator measures how much CO 2 a ship emits for the transport work it does in a year, and rates it from A (best) to E (worst). The required level tightens every year against a 2019 reference line. In April 2025 the IMO set the reductions for 2027 to 2030:

A ship rated E in one year, or D for three years in a row, must prepare a corrective action plan in Part III of its Ship Energy Efficiency Management Plan (SEEMP), showing how it will get back to C or better. The SEEMP is verified before the ship's Statement of Compliance is issued.

Because CII depends on how a ship is operated, it is shaped on board as much as in the office: speed, waiting time at anchor, hull and propeller condition, trim and auxiliary load all move the rating.

The Net-Zero Framework and its delay

In April 2025, at MEPC 83, the IMO approved draft amendments to MARPOL Annex VI known as the Net-Zero Framework. They combine a global fuel standard, which limits the greenhouse-gas intensity of the fuel ships use and tightens over time, with a pricing mechanism: ships that exceed the limits would pay, and ships using zero or near-zero fuels could be rewarded. It was intended to apply from 2028.

Formal adoption was due at an extraordinary session in October 2025. After strong opposition from the United States and other countries, delegates voted 57 to 49, with 21 abstentions, to adjourn for one year, moving any decision to around October 2026. Industry groups have warned that the delay leaves owners ordering ships with long lives without knowing which fuels the rules will reward, and raises the risk of regional rules filling the gap.

The EU's rules

EU Emissions Trading System

Shipping companies with ships of 5,000 GT and above must surrender EU allowances for the CO 2 their ships emit on voyages within the EU (100%), on voyages into or out of the EU (50%), and at berth in EU ports. The obligation was phased in:

• 40% of 2024 emissions
• 70% of 2025 emissions
• 100% of emissions from 2026, when methane and nitrous oxide are also covered

The European Commission has said ships will not be charged twice for the same emissions if an IMO carbon price is adopted, though how that will work in practice has not been settled.

FuelEU Maritime

Since 1 January 2025, FuelEU Maritime has limited the greenhouse-gas intensity of the energy used on board ships of 5,000 GT and above calling at EU ports, whatever their flag. It is measured well-to-wake against a 2020 baseline of 91.16 gCO 2 e/MJ, and the required cut rises in steps: 2% in 2025, 6% in 2030, 14.5% in 2035, 31% in 2040, 62% in 2045 and 80% in 2050.

Ships can comply individually or as a pool, and companies that fall short pay a penalty.

What it means on board

• Data is a compliance item. Fuel consumption, distance, time and cargo figures feed CII, the EU MRV report, ETS and FuelEU. Errors in noon reports now carry a cost.
• Speed and waiting time matter. Slow steaming and "just in time" arrival improve CII directly. Masters and charterers increasingly agree speed and arrival time with the rating in mind.
• Hull and propeller condition matter. Fouling raises fuel use and worsens the rating; cleaning and coating schedules are part of the SEEMP.
• Power limits change how the ship is handled. A ship with an EEXI power limitation has less power available; the override for safety and emergencies is documented and must be used and recorded properly.
• New fuels bring new training. LNG, methanol and, later, ammonia need specific training under the IGF Code and new safety procedures. See our LNG propulsion guide.

Fuels and technology

No single fuel has won. LNG is the most widely used alternative today but is a fossil fuel and carries the risk of methane slip; methanol is growing on container ships, with bunkering networks spreading in Asia and Europe; ammonia and hydrogen are at pilot stage; biofuel blends offer a drop-in option for existing engines. Shore power, wind-assisted propulsion and efficiency retrofits reduce emissions whatever the fuel.

Green shipping corridors, such as the one renewed in June 2026 between Singapore and the ports of Los Angeles and Long Beach, are being used to prove fuels and supply chains on specific routes.

Frequently asked questions

What is the IMO's 2050 target?

Net-zero greenhouse-gas emissions from international shipping by or around 2050, with checkpoints of at least 20% by 2030 and 70% by 2040 against 2008 levels. The older target of halving emissions by 2050 was replaced in 2023.

What happens if a ship gets a D or E CII rating?

One E rating, or three D ratings in a row, requires a corrective action plan in SEEMP Part III showing how the ship will reach C or better. The plan is verified before the Statement of Compliance is issued.

Was the IMO Net-Zero Framework adopted?

Not yet. It was approved in April 2025, but in October 2025 member states voted to postpone adoption by a year.

Does the EU ETS apply to ships that are not EU-flagged?

Yes. It applies to ships of 5,000 GT and above calling at EU ports, whatever their flag: all emissions on voyages within the EU and half on voyages into or out of the EU.

Related guides

• The Energy Efficiency Existing Ship Index (EEXI)
• MARPOL and air pollution from ships
• Marine scrubbers: types and rules
• LNG propulsion systems
• What the IMO is and does

Sources

• International Council on Clean Transportation, "IMO's newly revised GHG strategy: what it means for shipping and the Paris Agreement", July 2023
• DNV, "IMO MEPC 83: GHG requirements approved, taking effect from 2028", April 2025
• Lloyd's Register, "New IMO CII guidelines require SEEMP Part III revisions", 2025
• Ship & Bunker, "IMO's MEPC meeting votes to delay adoption of Net-Zero Framework", October 2025
• Global Maritime Forum, "A guide to the IMO's Net-Zero Framework"
• Swedish Environmental Protection Agency, "Maritime transport in the EU Emissions Trading System"
• DNV, "FuelEU Maritime"
• Manifold Times, "EmissionLink calls for clarity as EU moves to prevent double carbon charges", June 2026