CORSIA is the only global market-based measure any industry has agreed to, and it is now in the last year of its First Phase. The rules are settled: a baseline of 85% of 2019 emissions running to 2035, a sectoral growth factor published annually, and offsetting requirements that only bite on flights between volunteering states until 2027, when almost every international flight comes into scope.
The arithmetic is where it gets interesting. IATA puts demand across the whole First Phase at 170 to 236 million units. Supply of CORSIA-eligible units is nearing 40 million tonnes. That is roughly a fifth of the low end of demand, in the final year of the period.
The shortfall is not a shortage of carbon projects. It is a shortage of signatures. A unit only counts for CORSIA if the host country issues a Letter of Authorisation and applies a corresponding adjustment to its own NDC, and most host countries have not built the machinery to do it. The rules that were supposed to be the blocker — Article 6.2 and 6.4 — were finalised. The bottleneck moved to national administration, which is a slower thing to fix and a much less discussed one.
The six slots
- Trigger — 130 states in; from 2027 almost every flight Settled
- Requirement — 85% of 2019 to 2035; 2024 factor 15.4% Settled
- Instruments — Four programmes approved for 2027-2029 Settled
- Readiness — About 40 Mt of supply against 170-236 Mt of demand In motion
- Economics — Listed futures exist; no single official price In motion
- Response — 99% reporting; buying behaviour not yet visible In motion
Or walk it as a path
Obligated operator
An aircraft operator flying between CORSIA participating states, or preparing for 2027
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1TriggerSettled
130 states in; from 2027 almost every flight
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2RequirementSettled
85% of 2019 to 2035; 2024 factor 15.4%
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3ReadinessIn motion
About 40 Mt of supply against 170-236 Mt of demand
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4EconomicsIn motion
Listed futures exist; no single official price
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5InstrumentsSettled
Four programmes approved for 2027-2029
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6ResponseIn motion
99% reporting; buying behaviour not yet visible
Project developer or supplier
Developing a project that could supply CORSIA-eligible units, and needing to know what makes one eligible
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1InstrumentsSettled
Four programmes approved for 2027-2029
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2ReadinessIn motion
About 40 Mt of supply against 170-236 Mt of demand
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3EconomicsIn motion
Listed futures exist; no single official price
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4TriggerSettled
130 states in; from 2027 almost every flight
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5RequirementSettled
85% of 2019 to 2035; 2024 factor 15.4%
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6ResponseIn motion
99% reporting; buying behaviour not yet visible
Observer
Learning the scheme — advisor, investor, journalist, policy analyst
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1TriggerSettled
130 states in; from 2027 almost every flight
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2RequirementSettled
85% of 2019 to 2035; 2024 factor 15.4%
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3InstrumentsSettled
Four programmes approved for 2027-2029
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4ReadinessIn motion
About 40 Mt of supply against 170-236 Mt of demand
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5EconomicsIn motion
Listed futures exist; no single official price
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6ResponseIn motion
99% reporting; buying behaviour not yet visible
The slots in full
Trigger Settled
Why does this reach me?
Scope is decided by the state pair, not by the operator's nationality, and the rule changes fundamentally in 2027. Checked 27 Aug 2026.
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Until the end of 2026, offsetting requirements apply only to flights between states that have volunteered
Both the Pilot Phase (2021-2023) and the First Phase (2024-2026) work this way. What decides your exposure is where you fly, not where you are registered.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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130 states are participating as of 1 January 2026
The First Phase opened on 1 January 2024 with 126. Participation in the first two phases is voluntary.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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From 2027 all international flights are in scope, with named exemptions
Flights to and from Least Developed Countries, Small Island Developing States, Landlocked Developing Countries, and states representing less than 0.5% of global international RTK in 2018 are exempt unless those states volunteer.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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The duty to report is far wider than the duty to offset, and has applied since 1 January 2019
Every operator emitting more than 10,000 tonnes of CO2 a year on international flights reports annually. The standards sit in Annex 16 Volume IV to the Chicago Convention and apply to all 193 ICAO member states.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
What does not exist
The current state-pair list has not been read directly this pass
ICAO's own pages sit behind bot verification, which was not bypassed. The participant count is taken from IATA's June 2026 fact sheet rather than from the ICAO list itself, so the pairs relevant to a specific route network have not been confirmed here.
Monitored since 2026-08-27 · last checked 2026-08-27
Richard’s view
The single most common mistake is treating CORSIA as something that applies to an airline. It applies to a route. Two carriers on the same tarmac can have completely different exposure, and the 2027 change flips the question from 'do my routes qualify' to 'which of my routes are exempt'.
Next step Someone else
Check your routes against the ICAO state-pair list
ICAO publishes the participating states and the Chapter 3 state pairs. Your own network against that list is the answer, and it is a reading exercise rather than an advisory one.
No commercial relationship. These are ICAO publications and no provider is needed to read them.
Requirement Settled
What would have to be true, in numbers?
The formula and the baseline are fixed to 2035. The 2024 growth factor is official; 2025 is still an estimate. Checked 27 Aug 2026.
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The baseline is 85% of 2019 international aviation emissions, from 2024 to the end of the scheme in 2035
Originally an average of 2019 and 2020. The Council used 2019 alone for 2021-2023 after the pandemic collapsed 2020 traffic, and the 41st Assembly in October 2022 set 85% of 2019 for the remainder — a tightening the industry supported.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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No offsetting requirement accrued at all in the Pilot Phase
The Sectoral Growth Factor was zero for 2021, 2022 and 2023, so the 2021-2023 period produced no final offsetting obligation.
IATA CORSIA fact sheet, June 2026, citing ICAO's published annual SGF · checked 2026-08-27 verified
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The official 2024 growth factor is 15.4%, giving a sector requirement of 55.6 Mt
IATA CORSIA fact sheet, June 2026, citing ICAO · checked 2026-08-27 verified
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The 2025 factor is estimated at 16.1% to 20.9%, implying 58.8 to 81.5 Mt
Mid-point 18.6% and 70.2 Mt. This is IATA's estimate, not an ICAO publication, and should be quoted as such.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 reported
What does not exist
The 2026 sectoral growth factor has not been published
It is the last input needed to close out First Phase obligations, and the period ends in four months.
Monitored since 2026-08-27 · last checked 2026-08-27
An operator's own requirement cannot be stated here
It is the sector growth factor applied to that operator's own traffic on covered routes. The formula is public; the input is yours.
Monitored since 2026-08-27 · last checked 2026-08-27
Richard’s view
The Pilot Phase producing a zero obligation is worth remembering whenever anyone describes CORSIA as having been running since 2021. In cost terms it started in 2024.
Next step Someone else
The IATA CORSIA Handbook sets out the calculation
The baseline, the growth factor and the compliance arithmetic are all published. For an operator's own number, the input is its own verified emissions on covered routes.
No commercial relationship with IATA. We are not aviation compliance specialists and will say so.
Instruments Settled
What counts as a valid response?
Only ICAO Council-approved programmes count, and the list for 2027-2029 was decided in late 2025. Checked 27 Aug 2026.
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Only units from programmes the ICAO Council has approved can be used for compliance
The Council approves periodically, on the recommendation of the Technical Advisory Body, against the ICAO CORSIA Emissions Unit Eligibility Criteria.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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Four programmes are approved for the Second Phase, 2027-2029
American Carbon Registry, Architecture for REDD+ Transactions, Gold Standard and Verified Carbon Standard, following the Technical Advisory Body's assessment in October 2025.
ICAO — expanded approved emissions unit programmes · checked 2026-08-27 reported
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Eligibility turns on host country accounting, not only on project quality
Alongside additionality, permanence, leakage, unit tracking and safeguards, the criteria require the host country to agree to account for units issued so that double claiming cannot occur between the operator and the host country, following Article 6.2 guidance.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
What does not exist
The consolidated ICAO eligible-units table has not been read directly
ICAO's page is behind bot verification, which was not bypassed. The four-programme figure for 2027-2029 comes from ICAO's own announcement rather than the table, and the full First Phase list has not been re-read this pass.
Monitored since 2026-08-27 · last checked 2026-08-27
Richard’s view
The eligibility criteria are usually discussed as a quality bar on projects. The clause that actually decides whether a unit can be used is the double-claiming one, and that is a clause about a government, not a project.
Next step Someone else
ICAO publishes the approved programme list
The consolidated document names every programme approved for the Pilot, First and Second Phases. Programme selection is well served by existing brokers and the programmes themselves.
No commercial relationship with any programme. We are not the right call for CORSIA unit procurement.
Readiness In motion
Can this actually be done today?
Demand for the First Phase is five times the eligible supply, and the constraint is government authorisation rather than project availability. Checked 27 Aug 2026.
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Demand across the whole First Phase is estimated at 170 to 236 million units
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 reported
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Supply of CORSIA-eligible units is nearing 40 Mt
From projects across a range of host countries and project types. Set against an estimated 200 Mt of demand, that is roughly a fifth of what is needed, in the final year of the period.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 reported
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The binding constraint is the Letter of Authorisation and the corresponding adjustment
A unit only counts if the host country authorises it and adjusts its own NDC so the reduction is not counted twice. IATA calls the delay in issuing LoAs one of the most significant barriers to First Phase compliance.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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The reasons given are administrative, not legal
IATA names host countries' lack of awareness of how to implement, and reluctance to build the authorisation infrastructure. The Article 6.2 guidelines and the Article 6.4 rules, modalities and procedures are finalised, so rule uncertainty is no longer the explanation.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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Eligible supply is being competed for by buyers outside aviation
IATA notes that existing CORSIA-eligible units attract demand from other sectors because of their environmental integrity, which tightens availability further.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
What does not exist
No published count of host countries that have actually issued Letters of Authorisation
It is the single number that would tell an operator whether supply is about to improve. It is not published in one place, so the shortfall can only be inferred from the aggregate supply figure.
Monitored since 2026-08-27 · last checked 2026-08-27
Richard’s view
This is the fact that reframes the whole subject. Almost every discussion of CORSIA is about price, and price is a symptom. A credit becomes usable when a civil servant in the host country signs an authorisation and accepts a corresponding adjustment against their own national target — which is a political act, not a market one. India has both the project pipeline and the Article 6 machinery to be a supplier here, and very little has moved.
Next step Our service
Whether an Indian project can realistically be authorised
What the Article 6.2 authorisation pathway actually requires of an Indian host project, what a corresponding adjustment costs the national account, and whether a given pipeline is a plausible candidate. Scoped and priced before any work begins.
This is our service, and the disclosed interest is real: Richard is CEO of Carbon Registry India, a non-profit standard and an NCCF initiative. We do not sell CORSIA units and have no position in them.
Economics In motion
What does it cost, and what is it worth?
A listed market exists but there is no single official assessed price, and published figures diverge widely. Checked 27 Aug 2026.
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CORSIA Eligible Emissions Units for 2024-2026 are listed as futures and options on ICE
A listed contract means there is a reference market, which is more than most compliance instruments have at this stage.
ICE product listing · checked 2026-08-27 verified
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Early First Phase transactions settled around EUR 19 per tonne
Reported around Guyana's first ART TREES credits in late 2024. A transaction price, not an assessment.
Secondary market reporting · checked 2026-08-27 reported
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ICAO's 2025 Periodic Review put the average First Phase price in a USD 10 to 40 range
Explicitly based on limited price information. A four-fold range is a statement about opacity, not about the market.
ICAO 2025 CORSIA Periodic Review, via secondary reporting · checked 2026-08-27 reported
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Projections to 2027 run from the low twenties to above EUR 55 depending on supply
Sylvera models EUR 23 to 33 per tonne under base-case supply and above EUR 55 in a supply-constrained scenario. A model, not a price.
Sylvera market modelling, via secondary reporting · checked 2026-08-27 reported
What does not exist
No public settlement or volume data for the listed contract
Without it, the difference between a quoted price and a traded price cannot be established, and every published figure here is either a single transaction, an estimate, or a model.
Monitored since 2026-08-27 · last checked 2026-08-27
Richard’s view
Anyone quoting one CORSIA price is choosing a source. The honest position for a cost model today is a range with the supply assumption stated explicitly, because the spread between the base case and the constrained case is larger than the price itself.
Next step Someone else
The exchange and the price reporting agencies
ICE for the listed contract, and the price reporting agencies for assessed values. We do not assess prices and would be a worse source than either.
No commercial relationship with any exchange or price reporting agency.
Response In motion
What are the options, and what are others choosing?
Reporting compliance is near universal. Purchasing behaviour is not yet observable, because cancellation falls due after the period closes. Checked 27 Aug 2026.
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128 states submitted 2024 emissions data during 2025, covering about 99% of international aviation CO2
Per the ICAO CORSIA Central Registry, following a similar pattern to 2023. Whatever else is unresolved, the measurement layer works.
IATA CORSIA fact sheet, June 2026, citing the ICAO CORSIA Central Registry · checked 2026-08-27 verified
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Compliance is demonstrated by cancelling units after each three-year period closes
So First Phase purchasing decisions are being made now but the cancellations, and the evidence of what operators actually bought, come afterwards.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
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The industry response so far has been aimed at host governments rather than at the market
IATA, the Article 6 Implementation Partnership, IETA and ATAG published a host-country guidance document at COP29 on issuing Letters of Authorisation and performing corresponding adjustments, and IATA is running direct implementation assistance with host parties.
IATA CORSIA fact sheet, June 2026 · checked 2026-08-27 verified
What does not exist
No operator-level cancellation data for the First Phase
Until units are cancelled after the period closes, any account of how airlines are responding is inference from announcements rather than observation of behaviour.
Monitored since 2026-08-27 · last checked 2026-08-27
Richard’s view
That the industry's main effort is lobbying host governments rather than buying credits tells you where the participants themselves think the problem is. It matches the supply arithmetic exactly.
Next step Nobody yet
No cancellation record to benchmark against yet
Peer benchmarking on First Phase compliance is not possible until units are cancelled after the period ends, and we will not manufacture it from announcements. We monitor this weekly and the slot will change when the data appears.
Monitored since 27 Aug 2026. Last checked 27 Aug 2026.
Not citable — deliberately withheld
| Claim | Why it is not used |
|---|---|
| Supply limited to 15.8 million credits from Guyana | Circulates in secondary coverage but conflicts with IATA's own June 2026 figure of nearly 40 Mt. Not reconciled, so neither is used as a precise number. |
| Any single 'CORSIA price' | Published figures range from EUR 19 transactions to a USD 10-40 official range to EUR 23-55 projections. Quoting one is choosing a source. |
| The number of host countries that have issued Letters of Authorisation | Not published in any single place. Inferring it from aggregate supply would be a guess presented as a count. |
| Phase 1 approved programme list | The consolidated ICAO table sits behind bot verification and was not read this pass. Only the 2027-2029 approvals are stated. |
Beta — read this before you rely on a figure
What this is. Each track answers the same six questions about one subject and shows the date each answer was last checked. Every claim names the primary document it came from. Where something does not exist yet, that is stated with the date the watch began.
What beta means here. The system that assembles these pages is new. Slots may be drafted by an automated research process before an editor reviews them, and no page is published until a person has read it and signed it off. Some sources cannot be read automatically, and where that is true the page says so rather than reporting an unchanged figure.
Check the source before you act. These pages are a starting point for your own reading, not a substitute for it. Rules, prices, accreditations and eligibility lists change between checks, and a date on this page is the date it was last verified, not a guarantee it is current today. Every claim links to the document it came from. Use that document.
Not advice. Nothing here is legal, financial, compliance or investment advice, and it is not a recommendation to buy, sell or retire any carbon credit or to take any regulatory position. It does not create a client relationship. For a decision that carries money or liability, take professional advice on your own facts.
Interests to declare. Richard N. Bright is CEO of Carbon Registry India, a non-profit standard and an NCCF initiative, and provides paid advisory services. Where a track points a reader towards those, it is disclosed on that slot. Most slots point somewhere else, and some point nowhere, which is the honest answer more often than the field admits.
Corrections. If a figure here is wrong, say so and it will be corrected and dated. That is the fastest way to make this better, and it is welcome.