Airlines and other aircraft operators will be subject to offsetting requirements, which will be determined by the CO2 they emit on flights subject to offsetting. This includes all aircraft operators, from large passenger airlines, cargo airlines, some business aviation, and even some private aviation.
The implementation of CORSIA has been divided into three phases: The Pilot Phase, The First Phase, and The Mandatory Phase.
The Pilot Phase (2021-2023) and The First Phase (2024-2026) are voluntary for States to participate in. However, it is mandatory for airlines to offset their emissions from flights between states that are participating in the scheme starting in 2021. According to ICAO, as of January 2023, 115 States have announced their intention to participate in CORSIA. Nine more States (Antigua and Barbuda, Kuwait, Samoa, Seychelles, Sierra Leone, Solomon Islands, Mauritius, Malawi, and Haiti) announced their intention to participate in CORSIA from January 2024, bringing the total number of participating States to 124.
In The Mandatory Phase (2027 – 2035), non-exempt states will be forced to join based on 2018 RTKs thresholds. Consequently, Russia, Brazil, Vietnam, China and India will join the scheme from 2027. In compliance with CORSIA, operators flying between non-exempt and volunteering states will offset emissions based on the average CO2 growth of the aviation sector. For a complete list of participating and exempt countries, visit the ICAO website.