- 2021 to 2023: A ‘pilot’ voluntary phase of countries choosing to be part of the scheme. So far, 65 states (which together represent over 85% of air traffic, according to ICAO) have volunteered to be included in the scheme from the beginning.
- 2022: A review will be conducted to determine if there need to be any adjustments.
- 2024 to 2026: First implementation phase, also on a voluntary basis.
- 2027 to 2035: The mandatory phase, which will include all states except least developed, small island states and countries with a small amount of international air traffic (less than 0.5% of global traffic).