IMO Net-Zero Framework and GHG Fuel Intensity

A ship that loads heavy fuel oil will, once the framework is in force, pay a price set by the International Maritime Organization for the carbon it emits, and the price depends on a number almost no operator tracked before: the greenhouse-gas intensity of the energy the ship buys, measured from the wellhead to the wake. That number is the GHG Fuel Intensity, the GFI, and it is the spine of the IMO Net-Zero Framework approved as draft MARPOL Annex VI amendments at MEPC 83 in April 2025. The framework is approved but not yet adopted: the extraordinary session called to adopt it, MEPC/ES.2 in October 2025, adjourned for one year, so the dates and figures below are the values in the approved draft, not yet adopted treaty text. This article is the hub for the IMO Net-Zero Framework & GFI cluster. It explains the metric, the two-tier targets that bite each year, the remedial and surplus units that settle the bill, and the IMO Net-Zero Fund that collects the money, then routes down to the cluster leaves that carry the arithmetic and the governance detail. The marine Global Fuel Standard methodology works the calculation step by step, and the GFI reduction trajectory 2027 to 2050 lays out the full year-by-year path.

The framework is a single mechanism doing two jobs at once: a fuel standard and a carbon price welded together. The fuel-standard half sets a required GFI that falls every year, so a ship must lower the lifecycle intensity of its energy or fall short. The carbon-price half puts a dollar figure on the shortfall through remedial units, & rewards the ships that beat the target with surplus units that have resale value. The result is the first emissions-pricing regime that covers a whole global industry rather than one trading bloc, and it sits on top of the design and operational rules already in force: EEXI on the design side, the Carbon Intensity Indicator on the operational side, and now GFI on the fuel-lifecycle side.

What the GHG Fuel Intensity actually measures

GFI is grams of carbon-dioxide equivalent per megajoule of energy, written gCO2e/MJ. The unit choice matters. EEXI and CII both work in mass of CO2 per unit of transport work, so they reward a ship that moves more cargo per gram emitted. GFI ignores transport work entirely and asks a narrower question: for each unit of energy this ship consumed, how much greenhouse gas reached the atmosphere across the fuel’s whole life. A ship that burns less energy per mile does not improve its GFI; only changing the fuel does.

The “well-to-wake” basis is the part that separates GFI from every metric before it. The accounting splits into two stages. Well-to-tank covers the emissions from extracting, producing, & delivering the fuel to the ship’s tank, the stage CII never counts. Tank-to-wake covers the emissions from burning the fuel on board. GFI sums the two and weights each greenhouse gas by its global-warming potential, so methane slip from a dual-fuel engine and nitrous oxide from combustion count against the figure, not only CO2. The well-to-wake fuel pathways article works through how a single fuel can carry very different intensities depending on how & where it was made, and the well-to-wake intensity article carries the underlying lifecycle accounting.

The decision to count all three gases in CO2-equivalent, not CO2 alone, changes the standing of fuels that look clean only on a tank-to-wake CO2 basis. LNG burns with less CO2 per unit of energy than heavy fuel oil, but a low-pressure dual-fuel engine slips unburned methane, and methane has a global-warming potential far above CO2 over a 100-year horizon, so the slip can erase much of the CO2 advantage once it is weighted into the GFI. The same logic applies to nitrous oxide from combustion. By converting every gas to a single CO2-equivalent figure, GFI prices the methane-slip problem that the tank-to-wake CO2 measures behind EEXI and CII do not see, which is why an LNG ship can hold a respectable CII rating and still face a GFI position that reflects its slip. The conversion uses the 100-year global-warming-potential values from the IPCC Fifth Assessment Report (AR5), the basis the IMO LCA Guidelines in Resolution MEPC.391(81) carry: methane at 28 times CO2 and nitrous oxide at 265 times CO2 over a 100-year horizon. The EU’s FuelEU Maritime measure uses the same AR5 28 and 265, so both regimes weight the non-CO2 gases identically. The detailed lifecycle defaults and any later move to AR6 values sit in the implementation guidelines rather than the headline framework, so the precise weighting a given fuel carries is a guideline figure, not a framework constant.

The 2008 reference and the zero-near-zero line

Every target in the framework is stated as a percentage cut against one number: 93.3 gCO2e/MJ, the IMO’s reference value for the fleet-average fossil-fuel intensity in 2008. The same 2008 baseline anchors the 2023 GHG Strategy, so the GFI trajectory & the strategy’s emission checkpoints read against a common origin. Anchoring to a fixed year, rather than to each ship’s own past, means a ship cannot meet the standard by trimming its own historical intensity; it has to track the falling line the IMO sets for the whole fleet.

At the clean end, the IMO defines a zero or near-zero GHG technology, fuel, or energy source, the “ZNZ” class, as one with a GFI of no more than 19.0 gCO2e/MJ, which is 80% below the 93.3 reference. That single threshold is what makes the framework a fuel-transition lever rather than an efficiency tweak: a ship can shave its CII with slow steaming & trim, but it cannot get near 19.0 gCO2e/MJ without leaving fossil fuel behind. The ships that reach it earn the framework’s rewards rather than paying its penalties. The decarbonization and alternative fuels hub covers which pathways can credibly clear that line and which cannot, and the well-to-wake fuel pathways article works through which production routes land a given fuel above or below it.

The ZNZ line is not fixed. The 19.0 gCO2e/MJ threshold holds through 2034, and from 2035 it tightens to 14.0 gCO2e/MJ, so a fuel that just clears the bar in the early years can fall on the wrong side of it later without a cleaner feedstock or process. That step matters for an owner contracting a long-term fuel supply: a pathway certified at 17 gCO2e/MJ counts as ZNZ in 2030 but not in 2035, which means the eligibility for reward, not just the size of any deficit, can flip on a known date.

The two-tier target structure

The framework does not set one pass-fail line. It sets two, and the gap between them is where the pricing lives. The looser line is the Base target. The stricter line is the Direct Compliance target. Both are required GFI values that fall each year against the 93.3 reference, and a ship’s attained GFI for the year is checked against both.

A ship at or below the Direct Compliance target has complied fully through its own fuel: it owes nothing and, if it sits below the line, earns surplus units. A ship between the Direct Compliance target and the Base target has a Tier 1 compliance deficit for the emissions in that band. A ship above the Base target carries that Tier 1 deficit plus a Tier 2 compliance deficit for the emissions above the Base target. So a heavy-fuel-oil ship that takes no action faces both tiers at once, while a ship part-way through a fuel switch may clear the Base target & owe only the Tier 1 band.

The two targets diverge sharply over time. In the approved draft the Base target reaches a 4% reduction in its first compliance year, 8% by 2030, & 30% by 2035 against the reference; the Direct Compliance target reaches 21% by 2030 and 43% by 2035. The Base target keeps pulling, reaching a 65% reduction by 2040. These are the percentages in the draft amendments approved at MEPC 83; they are not yet adopted treaty text, and the first compliance year shifts with the entry-into-force date set once adoption occurs. The Tier 1 required GFI standard article carries the draft regulatory text behind these lines and how the required values are derived for a given year.

Proposed GFI reduction targets in the approved-but-not-yet-adopted MEPC 83 draft (percentages vs the 93.3 gCO2e/MJ 2008 reference; the year labels track the original timeline, which shifts with the entry-into-force date):

The numbers in the table are the proposed values in the draft for the years it fixes; the intermediate years between 2028 & 2035 step up on a set schedule, and the values beyond 2035 are to be set in later review. A ship’s attained GFI is the figure it controls through fuel choice and energy management, and the marine Global Fuel Standard methodology shows how the attained figure is built from the energy used and the certified intensity of each fuel.

Reading the two lines together explains why the framework would bite unevenly across the fleet. A heavy-fuel-oil ship sits at roughly the 93.3 reference, so in the first compliance year it is about 17 percentage points above the Direct Compliance target and about 4 points above the Base target, and it owes on both bands at once. A ship part-way through a fuel switch, say one running a blend that lands it 10% below the reference, clears the Base target in the early years and owes only on the Tier 1 band between the two lines. The same ship’s position erodes as the targets fall: a 10% margin that clears the first-year Base target of 4% no longer clears the 2030 Base target of 8% if the fuel mix stays put. The required values fall every year, not in steps the operator can ignore between the headline years, so the Tier 1 required GFI standard article gives the per-year figures rather than only the milestone percentages.

Remedial units, surplus units, and the price of a deficit

A compliance deficit is not a fine; it is a quantity of CO2-equivalent the ship must balance by surrendering units. The units come in three forms. Surplus units are earned by a ship that beats the Direct Compliance target. Remedial units are bought by a ship in deficit. Banked or transferred units move surplus from where it was earned to where it is needed.

The prices are what make the mechanism a carbon price. In the approved draft, for the first three-year period (originally 2028 to 2030) the Tier 1 remedial unit costs US$100 per tonne of CO2-equivalent, and the Tier 2 remedial unit costs US$380 per tonne of CO2-equivalent. These are proposed values in the draft, not yet adopted. The US$280 spread is deliberate: emitting in the worst band, above the Base target, costs nearly four times as much per tonne as emitting in the Tier 1 band. Both figures are fixed only through 2030 & are subject to review for the periods that follow, so an owner sizing a long-term fuel investment cannot treat the 2028 prices as permanent.

A ship with a surplus is not stuck holding it. It can bank surplus units for use within the two following calendar years, or transfer them to a ship in deficit. That creates a thin internal market: a ship running on a low-lifecycle fuel can monetize the surplus it generates, which is part of how the framework intends to reward early movers rather than only punish laggards. The mechanics of how units are issued, verified, & surrendered are the subject of the cluster’s compliance-side leaves.

Where the money goes

The revenue from remedial units flows into the IMO Net-Zero Fund. The fund is built to do two things with the money: reward ships using zero or near-zero technologies, and support developing countries, with explicit attention to Small Island Developing States and Least Developed Countries that face the heaviest exposure to both climate impacts and transition costs. So the framework is not a pure penalty pool; a share of what the dirtiest ships pay is meant to circulate back as a reward to the cleanest, narrowing the cost gap that has kept low-lifecycle fuels off the market. The IMO Net-Zero Fund governance and disbursement article covers how the fund is administered and how disbursements are decided. The exact ZNZ reward rate per tonne was not fixed at MEPC 83; it is one of the figures the implementation guidelines and the fund’s disbursement rules have to set, and an early mover sizing the upside of a clean-fuel contract is doing so against an incentive whose value is not yet a number.

How a ship’s attained GFI is built and reported

The attained GFI is the figure a ship controls, and it is built from two inputs the framework treats as separate: the energy the ship consumed, and the certified well-to-wake intensity of each fuel that supplied it. For a calendar year, a ship sums the energy from every fuel it burned, in megajoules, weights each fuel stream by its certified gCO2e/MJ, and divides the total CO2-equivalent by the total energy. The result is one number for the ship for the year, an energy-weighted average lifecycle intensity. A ship that ran 90% on heavy fuel oil and 10% on a low-intensity fuel does not get the clean fuel’s number; it gets the blend, weighted by the energy each contributed. The marine Global Fuel Standard methodology works that calculation step by step, including how the energy of each fuel is converted from mass using its lower calorific value, and the attained GFI calculator runs the energy-weighted average for a given fuel mix. The same lifecycle logic drives the EU’s parallel metric, which the FuelEU GHG intensity calculator computes against the 91.16 gCO2e/MJ EU reference.

The certified intensity is the part a ship cannot self-assert. A fuel’s well-to-wake number comes from the lifecycle-assessment guidelines and the documented production pathway, recorded on a fuel-supply document that travels with the bunkers, not from a generic fuel-type assumption. Two deliveries of the same fuel name can carry different certified intensities if they were made from different feedstocks by different processes, which is why the well-to-wake fuel pathways article matters to the arithmetic: the pathway, not the fuel name, sets the number that goes into the average. Where a fuel has no certified value, the guidelines fall back on a default, and the defaults are deliberately conservative, so an operator that wants to claim a low intensity carries the documentation burden to prove it.

The reporting runs on the machinery already built for the IMO Data Collection System and CII. A ship records fuel consumption by type over the year, the data is verified, and the verified figures produce both the CII rating and, once the framework enters force, the attained GFI. The draft does not pin the first reporting period to a fixed calendar year: it begins with the first full compliance year after entry into force, which the October 2025 adjournment pushed back from the original 2028 target. The verification step is what gives the number legal weight: an attained GFI is not the operator’s estimate but a verified figure that the administration or a recognized organization has checked against the fuel-supply records.

The verification, deficit, and surrender cycle

The framework runs on an annual cycle, and the steps fall in a fixed order. Through the year a ship bunkers fuel and logs consumption by type with its supporting fuel-supply documents. After the year closes, the consumption data is verified and the attained GFI is computed and checked against the two required values for that year. The gap, if any, between attained GFI and each target, multiplied by the energy in the relevant band, gives the deficit in tonnes of CO2-equivalent, split into a Tier 1 quantity and a Tier 2 quantity. The GFI compliance calculator splits an attained figure into the two bands and sizes the remedial-unit cost at the draft Tier 1 and Tier 2 prices.

The ship then settles. A ship below the Direct Compliance target receives surplus units for the margin. A ship in deficit acquires the matching remedial units, Tier 1 at US$100 per tonne CO2eq and Tier 2 at US$380 per tonne CO2eq for the first three-year period in the approved draft, by contributing to the IMO Net-Zero Fund, or it sources surplus units transferred from another ship. The deficit must be balanced within the settlement window the guidelines set; an unbalanced deficit is a non-compliance the flag state and port state can act on through the existing MARPOL Annex VI enforcement chain, including the Statement of Compliance a ship needs to trade. The framework’s teeth are not a separate fine but the same trading-document pressure that backs EEXI and CII compliance today: a ship that cannot show it has settled its position risks its certificate, and without the certificate it cannot trade.

The cycle repeats every year against a target that has fallen, so a ship that did nothing between two years sees its deficit grow even with identical operations and fuel, because the required GFI it is measured against dropped. That ratchet is the mechanism’s whole point: standing still is a rising cost, not a flat one.

The flexibility mechanisms: banking, transfer, and pooling

The framework is not a per-ship pass-fail wall; it builds in three ways to move compliance between ships and across years, and the design of those mechanisms decides how cheaply the fleet as a whole can comply. The first is banking. A ship that earns surplus units can hold them for use within the two following calendar years, so a strong year can cover a weaker one without an outside transaction. The two-year limit stops surplus from being hoarded indefinitely, which would let early over-compliance dilute the later, tighter targets.

The second is transfer. Surplus units can move from the ship that earned them to a ship in deficit, which creates a market price for over-compliance somewhere between zero and the remedial-unit price. A ship running a low-lifecycle fuel can monetize its surplus rather than only avoiding a cost, and a ship in deficit can buy that surplus instead of paying the fund, as long as the surplus is cheaper than the matching remedial unit. The transfer market is what turns the framework from a tax into a trading system, and it is the channel through which the reward for clean fuel reaches the ships that switch early.

The third area, the treatment of fleets and pools, is among the details the implementation guidelines have to settle, and it is where the IMO regime and the EU’s FuelEU Maritime measure differ most. FuelEU lets operators pool ships so a clean ship’s surplus offsets a dirty ship’s deficit inside one verified pool, a flexibility the FuelEU compliance balance and pooling rules spell out. How far the IMO framework allows the same fleet-level netting, versus requiring each ship to settle on its own with traded units, is one of the open questions for the 2026 guidelines, and it materially changes the compliance cost for an operator running a mixed fleet.

The commercial calculus for an operator

The framework turns fuel choice into a priced decision, and the arithmetic an operator runs is a comparison, not a single number. The cost of staying on a high-intensity fuel is the deficit it generates times the remedial-unit price, layered across both tiers; the cost of switching is the fuel-price premium of the cleaner option. The framework is calibrated so that, as the targets tighten and the fuel premium for low-lifecycle fuels narrows, the switch becomes the cheaper path, but the crossover year depends on the specific fuel premium an operator faces, which the framework does not set.

A worked sense of scale makes the lever concrete. The Tier 2 price of US$380 per tonne CO2eq is the cost of emitting in the dirtiest band, above the Base target; the Tier 1 price of US$100 is the cost in the band between the two targets. A ship that clears the Base target but misses Direct Compliance pays only the US$100 rate on its Tier 1 quantity, which is why moving from "no action" to "meets the Base target" removes the expensive Tier 2 exposure entirely and is the first move most operators will make. The US$280 spread between the tiers is the framework’s strongest single signal: it is not the absolute price but the gap that pushes a ship out of the worst band first.

The harder part of the calculus is that the numbers move. The remedial-unit prices are fixed only through 2030, the targets beyond 2035 are unset, the ZNZ line tightens from 19.0 to 14.0 gCO2e/MJ in 2035, and the ZNZ reward rate is not yet a figure. An owner contracting a 15-year fuel supply or ordering a dual-fuel newbuild is committing capital against a price curve whose later years are still being written, which is the central commercial risk the decarbonization and alternative fuels decisions turn on.

How GFI sits with the rest of the rulebook

The Net-Zero Framework does not replace the measures already in MARPOL Annex VI. It stacks on them, and a ship must satisfy each on its own terms. The ship efficiency indices overview covers how the design and operational layers fit together; the short version is that each layer answers a different question.

EEXI answers a design question, once. It is the attained energy-efficiency index of an existing ship, computed from installed power and reference speed, and a ship either meets its required EEXI through power limitation and efficiency devices or it does not trade. EEXI, EPL, and ShaPoLi covers the power-limitation route most existing ships took to comply. CII answers an operational question, every year. It rates a ship A to E on the carbon it actually emitted per cargo-tonne-mile, and a string of poor ratings forces a corrective action plan; the CII rating calculator places a ship in its A to E band for the year. A ship can hold a strong CII band and still owe a GFI deficit, because the two measure different things. Both EEXI & CII work tank-to-wake and count only the CO2 from combustion.

GFI answers a fuel-lifecycle question, every year, and that is the gap it fills. A ship can hold a B-rated CII on conventional fuel and still owe a large GFI deficit, because GFI prices the well-to-tank emissions of producing that fuel, which CII does not see, and rewards a switch to a fuel with a low lifecycle intensity, which CII does not reward. The two pull in compatible directions but on different axes: CII pushes a ship to run more efficiently, GFI pushes it to buy cleaner energy. Slow steaming and CII shows the operational lever; GFI is the fuel lever beside it.

The framework also runs alongside, not inside, the European Union’s carbon measures. A ship trading to and from EU ports faces the EU Emissions Trading System and the FuelEU Maritime intensity standard at the same time as the IMO regime, and the two are not yet reconciled, so an operator can face an EU charge and an IMO remedial-unit cost on the same voyage. The interaction between the global IMO price and the regional EU price is one of the live questions the EU maritime carbon pricing hub tracks.

The 2023 GHG Strategy that the framework serves

The GFI targets are not free-standing numbers; they are the instrument chosen to hit the ambition the IMO set in 2023. Resolution MEPC.377(80), adopted 7 July 2023, replaced the 2018 initial strategy with a stronger one. It sets indicative checkpoints on total annual GHG emissions from international shipping, all measured against 2008, & a long-term net-zero ambition. The framework’s job is to make those checkpoints reachable rather than aspirational.

The strategy keeps two distinct kinds of target apart, & the distinction matters when reading the GFI trajectory against it. The carbon-intensity checkpoint, at least a 40% cut by 2030, is the one the EEXI & CII regime was built to deliver, because those measures work on intensity per unit of transport work. The total-emissions checkpoints, 20% striving 30% by 2030 and 70% striving 80% by 2040, depend on the absolute volume of fuel burned, which is why the framework needed a fuel-lifecycle lever like GFI on top of the efficiency rules: an efficient fleet that keeps growing can improve its intensity while its total emissions rise. The fuel-uptake checkpoint, 5% striving 10% ZNZ energy by 2030, is the one GFI most directly targets through the 19.0 gCO2e/MJ ZNZ threshold and the surplus-unit reward.

The strategy is itself due for review. The IMO committed to keeping the 2023 strategy under review with a view to adopting a revised strategy in 2028, so the checkpoints and the GFI trajectory beyond 2035 can move. An owner planning a 20-year asset against these numbers is planning against a moving line, which is the central commercial risk of the transition.

The legal pathway from approval to enforcement

The framework’s status is precise, and the words matter because they decide what is binding. At MEPC 83, 7 to 11 April 2025, the committee approved the measures as draft amendments to MARPOL Annex VI, adding a new Chapter 5. Approval is not adoption. The draft was circulated and put to formal adoption at an extraordinary session, MEPC/ES.2, on 14 to 17 October 2025. Adoption is the step that fixes the treaty text; approval only clears it to be put to that vote.

That vote did not carry. On 17 October 2025 the committee adjourned MEPC/ES.2 for one year without adopting the framework: 57 member states voted to adjourn against 49 to proceed. The reconvened extraordinary session is set for around October 2026, and member states continue working toward consensus in the interim, with an Intersessional Working Group on GHG emissions having met 20 to 24 October 2025 on the implementation guidelines. So as of June 2026 the framework is approved but not adopted.

Entry into force then runs on MARPOL’s tacit-acceptance rule, the mechanism that lets the convention update without each amendment being re-ratified by every party. Under tacit acceptance an adopted Annex VI amendment enters into force a set period after a deemed-acceptance date. Because adoption did not happen on the original October 2025 schedule, the earliest possible entry into force has moved to about 1 March 2028, and later still if adoption slips again at or after the October 2026 session. The original timeline of in force 2027 with first reporting on 1 January 2028 no longer holds. So the dates now sit in this sequence: approved April 2025, adoption adjourned at MEPC/ES.2 in October 2025 by a 57 to 49 vote, reconvenes around October 2026, earliest entry into force about 1 March 2028, with the GFI obligations and reporting following after entry into force rather than pinned to 2028. An operator reading a single “2025” or “2027” headline can misjudge which year actually changes its costs; the safe reading is that no date is fixed until the IMO adopts the amendments.

The detailed rules that make the obligation operable were not all settled at approval. The lifecycle-assessment guidelines that assign each fuel its certified well-to-wake intensity, the fuel-certification and documentation rules, the verification procedures, and the IMO Net-Zero Fund’s disbursement mechanics are still being developed through the IMO’s working-group track, which continued after the October 2025 adjournment: an Intersessional Working Group on GHG emissions met 20 to 24 October 2025 to advance exactly this implementation work. Those guidelines are not optional detail: the certified intensity they produce is the input that would decide a ship’s attained GFI, so until they are fixed, an operator cannot compute an exact compliance position for a given fuel, only bound it. The architecture is treaty-grade in design; the numbers that would turn it into a per-ship bill are guideline work that, like the framework itself, is not yet adopted.

Why a fuel-lifecycle metric was needed on top of efficiency rules

The case for GFI is that the rules already in force could not, by construction, hit the 2023 Strategy’s absolute-emissions checkpoints. EEXI and CII both measure intensity per unit of transport work and count only tank-to-wake CO2. A fleet can improve both while its total emissions rise, because a more efficient ship that carries more cargo or sails more miles burns more fuel in absolute terms. The 2023 Strategy’s carbon-intensity checkpoint, at least a 40% cut per transport work by 2030, is the one EEXI and CII were built to deliver; the total-emissions checkpoints, 20% striving 30% by 2030 and 70% striving 80% by 2040, are not reachable by intensity gains alone.

A fuel-lifecycle metric closes that gap from two directions. It counts the well-to-tank emissions of producing the fuel, which an LNG or fossil-derived “blue” fuel can carry in large amounts even when its combustion CO2 looks low, so it removes the incentive to shift the emissions upstream where CII cannot see them. And it rewards the switch to low-lifecycle fuels directly through surplus units and the ZNZ threshold, which is the only lever that moves the absolute-emissions and fuel-uptake checkpoints rather than the intensity one. The ship efficiency indices overview sets out how the three layers, design, operation, and fuel lifecycle, answer three different questions, and GFI is the layer added precisely because the first two left the absolute and fuel-uptake targets unaddressed.

The well-to-wake basis also changes which technologies count as progress. A ship that cuts methane slip from a dual-fuel engine improves its GFI because methane is weighted by its global-warming potential, not ignored; the same ship sees no CII benefit, because CII counts only CO2. A ship that buys a certified low-lifecycle fuel improves its GFI even at the same speed and the same cargo, which is a result CII cannot produce. The metric was chosen because it prices exactly the choices, fuel feedstock, production route, and combustion-gas control, that the efficiency rules are blind to, and those are the choices the 2008-to-2050 transition turns on.

What is settled and what is still open

The architecture is agreed in the approved draft: a well-to-wake GFI metric, two annual targets, remedial and surplus units, and the IMO Net-Zero Fund, all in a new Chapter 5 of MARPOL Annex VI approved at MEPC 83. The reference value of 93.3 gCO2e/MJ, the ZNZ threshold of 19.0 gCO2e/MJ, the target percentages running to 2035, & the US$100 and US$380 remedial-unit prices for the first three-year period are the figures the draft proposes for that opening period. None of them is yet adopted treaty text: the extraordinary session called to adopt the framework, MEPC/ES.2 in October 2025, adjourned for a year, so even the architecture is “approved and near-certain” rather than “law.”

What is most open is the framework’s adoption itself. After the October 2025 adjournment, the measures return to an extraordinary session around October 2026, and nothing in the draft binds until that vote carries. Beyond adoption, most of what happens after 2030 is also unset. The proposed remedial-unit prices are fixed only through the first three-year period and are subject to review. The target percentages beyond 2035 are to be set later. The detailed implementation guidelines, including the fuel-certification rules that would decide a fuel’s well-to-wake intensity in practice, are still in development through the IMO’s intersessional working-group track, and the lifecycle-assessment defaults inside those guidelines will decide whether a given fuel pathway clears the ZNZ line. The interaction with the EU’s regional measures is unresolved. And the 2028 strategy review can change the ambition the whole framework is calibrated to. The numbers in this article are the proposed figures in the approved draft; both the figures and the timeline can still move, and the rules for the years beyond are still being written.

Limitations

This article describes the IMO Net-Zero Framework as approved at MEPC 83 in April 2025 and the figures proposed in that draft; the framework is not yet adopted. The extraordinary session convened to adopt it, MEPC/ES.2 on 14 to 17 October 2025, adjourned for one year (57 member states to adjourn against 49 to proceed) and reconvenes around October 2026, which moved the earliest possible entry into force to about 1 March 2028, later if adoption slips again. This is not a substitute for the MARPOL Annex VI Chapter 5 amendment text once adopted, the adopted resolution, or the implementation guidelines, which will carry the binding definitions and the exact computation rules. The target percentages, the reference value, the ZNZ threshold, and the remedial-unit prices stated here are the proposed values in the approved draft running to 2035; values for later periods are subject to the reviews built into the framework and the 2028 strategy review, and once the framework is adopted the controlling figures for any compliance year are those in force for that year. Any account that states the framework is already in force, or fixes its dates or unit prices as final law, is ahead of the record; treat the GFI mechanism as approved-but-pending until the IMO confirms adoption.

A ship’s attained GFI depends on the certified well-to-wake intensity of each fuel it burns, and those certified values come from the lifecycle-assessment guidelines and the fuel’s documented production pathway, not from a generic fuel-type assumption; the same fuel name can carry very different intensities depending on feedstock and process. The two-tier deficit and the unit prices set a compliance cost, not a fine, and the cost a given ship faces depends on its energy mix, its trading pattern, and the units it can bank or acquire, none of which this overview computes for a specific ship. The interaction between the IMO regime and regional measures such as the EU Emissions Trading System & FuelEU Maritime is not reconciled in regulation, so a voyage can attract more than one charge; an operator’s actual exposure must be assessed against the specific instruments that apply to its trade.

See also

• Attained GFI calculator: the energy-weighted well-to-wake intensity for a ship’s annual fuel mix.
• GFI compliance calculator: the Tier 1 and Tier 2 deficit split and the draft remedial-unit cost.
• Marine Global Fuel Standard (GFS) methodology: the step-by-step GFI calculation from energy used and certified fuel intensity.
• GFI reduction trajectory 2027 to 2050: the full year-by-year path of the Base and Direct Compliance targets.
• Tier 1 required GFI standard: the regulatory basis for the required-GFI values and the Chapter 5 text.
• IMO Net-Zero Fund governance and disbursement: how the fund collects and distributes the remedial-unit revenue.
• Well-to-wake fuel pathways: how a single fuel can carry different lifecycle intensities by feedstock and process.
• Well-to-wake intensity: the lifecycle accounting behind the GFI figure.
• Decarbonization and alternative fuels: which fuel pathways can clear the 19.0 gCO2e/MJ ZNZ line.
• Ship efficiency indices: how the EEXI, CII, and GFI layers fit together.
• EU maritime carbon pricing: the EU ETS and FuelEU Maritime measures that run alongside the IMO regime.
• What is CII?: the annual operational carbon-intensity rating.
• What is EEXI?: the one-time design-efficiency index for existing ships.
• EEXI, EPL, and ShaPoLi: the power-limitation route to EEXI compliance.
• Slow steaming and CII: the operational efficiency lever beside the GFI fuel lever.
• CII corrective action plan: what a poorly rated ship must do under CII.
• FuelEU Maritime explained: the EU’s well-to-wake intensity standard.