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In 2016, Governments adopted CORSIA, the Carbon Offsetting and Reduction Scheme for International Aviation, to stabilize net CO2 emissions from international aviation from 2021.

CORSIA has applied to international aviation since 1 January 2019 when all airlines were required to report their CO2 emissions on an annual basis. From 1 January 2021, international flights have become subject to offsetting obligations.

Offsetting is not intended to replace efforts to reduce the sector’s carbon emissions through technology, operational and infrastructure advances. CORSIA will not make airlines strive any less to increase the use of SAF and advocate for greater production, increase fuel efficiency as well as roll out other technological developments - as part of the industry's #FlyNetZero commitment.

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The IATA CORSIA Handbook is intended to provide information to airlines on the main elements of CORSIA and on requirements to comply with the scheme.

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CORSIA Baseline

Originally, the CORSIA baseline – from which airline offsetting requirements under the agreement are calculated – was agreed to be an average of 2019 and 2020 emissions. However, in 2020 the COVID-19 crisis caused a precipitous drop in demand for air transport to less than half that of 2019. As a result, the CORSIA baseline would have been significantly reduced, imposing an unexpected and severe economic burden on an already extremely weakened airline industry and contravening the spirit of the CORSIA framework agreed in 2016. Therefore, in June 2020, the ICAO Council agreed to use 2019 emissions only as CORSIA’s baseline for the period of 2021-2023.

Most recently, at its 41st Assembly, ICAO set 85% of 2019 emissions as CORSIA’s baseline from 2024 until the end of the scheme in 2035: a significantly more ambitious target than originally planned, which the industry supported.

> CORSIA factsheet (pdf)

Mitigating CO2 Emissions

The aviation sector is committed to advances in technology, operations, and infrastructure to continue to reduce its carbon emissions. Offsetting is not intended to replace these efforts. Nor would CORSIA make fuel efficiency any less of a day-to-day priority. Rather, CORSIA can help the sector achieve its climate targets in the short-and medium-term by complementing emissions reduction initiatives within the sector.

Achieving net zero CO2 emissions by 2050 is an ambitious aspirational goal and will require both in-sector measures, including continued investment in new technologies and strong support mechanisms for the deployment of SAF, as well as out-of-sector measures, such as offsetting and carbon removals.

Offsetting is an action by a company or individual to compensate for their emissions by financing a reduction in emissions elsewhere. Offsetting and carbon markets are fundamental components of global, regional, and national emissions reduction policies. They have operated for decades for compliance purposes and voluntary emissions reductions and continue to be an effective mechanism to underpin action against climate change, especially for hard-to-abate sectors.

Environmental Integrity

There are several ways to achieve CO2 reductions that can be used as offsets, many of which bring other social, environmental or economic benefits relevant to sustainable development. Such offsets can be sourced from various types of activities, including, for example, deployment of renewable energy, clean cooking technologies, methane capture, forestry, and other emissions-reducing or avoidance projects.

To ensure the environmental integrity of CORSIA, the ICAO Council has approved a list of eligible emissions units that can be used for compliance. The Council’s decision is informed by a recommendation from a Technical Advisory Body and guided by environmental criteria to guarantee that emissions units deliver the required CO2 reductions.

The criteria are based on principles commonly applied under existing trading mechanisms and well-accepted carbon offset certification standards.

Environmental Impact of CORSIA

CORSIA is a global scheme which will result in greater levels of CO2 mitigation in international aviation than could be achieved through domestic policy measures. It is forecast that CORSIA will stabilize net CO2 emissions from international aviation at about 600 million tonnes of CO2.

IATA estimates that, without CORSIA, the CO2 footprint of international aviation would increase from slightly over 600 million tonnes of CO2 in 2019 to almost 900 million tonnes of CO2 by 2035.

For more information, please refer to the CORSIA fact sheet

Reporting of Emissions

Under CORSIA, all airline operators with annual emissions greater than 10,000 tonnes of CO2 are required to report their emissions from international flights on an annual basis since 1 January 2019. Operators must keep track of their fuel use for each individual flight in order to calculate their CO2 emissions. They will have to apply one of the five approved fuel use monitoring methods. In certain circumstances, however, operators may be eligible to use simplified monitoring and estimate their emissions using the CO2 Estimation and Reporting Tool (CERT), developed in ICAO as part of CORSIA.

To guarantee the accuracy of the data reported by operators, annual emissions reports will need to be verified by an impartial third-party verification body, prior to submission to the State. Verification bodies will have to be accredited under ISO/IEC 17029:2019, ISO 14065:2020, and other relevant requirements.

Offsetting Requirements

Offsetting requirements started from 2021. Upon completion of each 3-year compliance period, operators will have to demonstrate that they have met their offsetting requirements by cancelling the appropriate number of emissions units.

Considering the special circumstances and respective capabilities of States, ICAO member States agreed to implement CORSIA offsetting requirements in phases.

  • From 2021 until 2026 (pilot phase from 2021 to 2024; and first phase from 2024 to 2026), only flights between States that volunteer to participate in CORSIA are subject to offsetting requirements. 
  • From 2027, all international flights will be subject to offsetting requirements. However, flights to and from Least Developed Countries, Small Island Developing States, Landlocked Developing Countries and States which represented less than 0.5% of the global international RTK in 2018 will be exempt from offsetting requirements unless these States participate on a voluntary basis.

> Credible carbon offsets vital to net zero (Airlines magazine, Sept 2022)

A Multilateral Approach

On 27 June 2018, ICAO adopted the international Standards and Recommended Practices (SARPs) for CORSIA as Annex 16, volume IV, to the Chicago Convention following Resolution A41-22 at the 41st Assembly of ICAO in October 2022, an amendment to the CORSIA SARPs and the preparation of its second edition is currently underway and can be expected in the second half of 2023.

The adoption of global standards for CORSIA ensures the necessary level of uniformity in regulations which our industry needs. Uniformity is not only key to prevent market distortions, but also to preserve the environmental integrity of CORSIA.

In order to avoid a patchwork of uncoordinated regional and domestic policies for international aviation, political agreement for CORSIA was achieved on the condition that CORSIA would be the only market-based measure applied to international flights and on the basis that emissions should not be accounted for more than once. Unfortunately, the success of CORSIA may be jeopardized by the national policies of some States. Of particular concern, is the action of some States in applying or considering the application of a carbon pricing instrument or ticket tax to address emissions from international aviation, on top of CORSIA. Such policies do not only conflict with the international commitments of these States, they also undermine multilateral efforts to deal with climate change and put at stake the credibility of the global approach, potentially compromising the international support for CORSIA at a critical time for its implementation.

Guidance materials & support

Under CORSIA, all operators with annual emissions greater than 10,000 tonnes of CO2 will have to report their emissions on an annual basis, with monitoring starting from 1 January 2019 (international flights only).

> Download the IATA CORSIA Handbook: 5th edition January 2024 (pdf)

Stay informed

Please let us know if you wish to stay informed about CORSIA and receive regular updates on new capacity-support activities and materials. To sign up, please send us a brief message at

You will also find additional guidance on CORSIA in the ICAO Environmental Technical Manual on the ICAO website.