The 2026 strategic roadmap: Navigating the final reconciliation of CORSIA phase 1

The Sectoral Growth Factor (SGF) and the 2025 Offsetting Requirement 

While operators have submitted their verified emissions data for 2025, their individual offsetting liability is currently “frozen” in a state of calculation. This liability is determined by the Sectoral Growth Factor (SGF), a variable that reflects the total international aviation sector’s emissions growth relative to the baseline (85% of 2019 levels).  

The October 2026 Trigger 

 The ICAO Council is mandated to publish the final 2025 SGF by October 31, 2026.  This Publication marks the beginning of the 2025 CORSIA offsetting reconciliation process. 

• The Notification Window: Following the SGF publication, National Authorities have until November 30, 2026, to formally notify each operator of their specific “Offsetting Requirement”(OR).
• The Calculation Formula: OR₂₀₂₅ = Verified 2025 Offsetting Emissions x SGF₂₀₂₅

For operations and compliance managers, this notification represents the shift from “data management” to “liability management”. Operators must ensure their finance team is briefed on the potential variance in credit prices once these official “offsetting obligations” are issued across the industry simultaneously. 

Procurement Strategy: Sourcing ICAO-Eligible EEUs 

With the 2025 liability quantified by year-end, the focus shifts to the procurement of CORSIA Eligible Emissions Units (EEUs). Unlike the voluntary carbon market, CORSIA has strict eligibility criteria that have evolved for the 2024-2026 period. 

Eligibility and Article 6 of the Paris Agreement 

A critical development in 2026 is the scarcity of units that carry a Letter of Authorisation (LoA) from host countries.  

Under Article 6 of the Paris Agreement, these “Corresponding Adjustments” (CAs) are required to ensure that a carbon reduction is not double-counted by both the aeroplane operator and the country where the project is located. 

• Approved Registries: Operators must ensure credits from ICAO-approved programs, including the American Carbon Registry (ACR), Architecture for REDD+ Transactions (ART), Gold Standard, Verra (VCS) and more. 
• Vintage Restrictions: Credits must fall within the approved “vintages” for the First Phase (2024-2026 compliance period). In general, eligible units must represent emissions reductions generated between 1 January 2021 and 31 December 2026, from projects whose first crediting period started on or after 1 January 2016. Using ineligible credits will lead to a rejection by the National Authority during the Emissions Units Cancellation Report check. 

The Cancellation Deadline 

While the 2025 SGF is issued in 2026, the physical “cancellation” of these credits (marking them as retired in a registry) for the entire 2024-2026 period must be completed by January 31, 2028. 

Completing the 2026 Monitoring Cycle 

The monitoring conducted right now will undergo independent third-party verification before April 30,2027. 

As a Verification Body, we emphasise the following for the 2026 cycle: 

• Data Consistency: Ensure that the fuel monitoring method (e.g., Method A, B, Block-off/Block-on, Fuel Uplift, Fuel Allocation with Block Hour) has remained consistent with your approved Emissions Monitoring Plan (EMP). 
• Managing Data Gaps: Operators must be vigilant in identifying “Data Gaps” in their data. Using the ICAO CORSIA CERT tool for gap-filling is acceptable, but only within the 5% threshold of the total offsetting flights. 
• New Route Analysis: If your airline has launched new international routes in 2026, verify immediately if the destination State is a CORSIA participant. 

Transitioning to Phase 2 (2027 and beyond) 

On January 1, 2027, while the 2026 verification is still underway, the industry enters the Second Phase. 

• Expanded Scope:  The transition to Phase 2 will see a mandatory increase in participating States. As a result, routes that were not subject to CORSIA offsetting requirements in 2026 may become subject to offsetting requirements from 2027 onwards. 
• Market Considerations: The transition to Phase 2 is expected to increase the overall demand for eligible emissions units, particularly those meeting ICAO eligibility criteria and Article 6 corresponding adjustment requirements. Operators should therefore closely monitor developments in the carbon market and ICAO eligibility updates while planning their future compliance strategy. 

Conclusion for the Aeroplane Operator 

 The 2026 monitoring year is not merely an administrative repetition of 2025. It represents the definitive “close-out” period for the first phase of CORSIA for aeroplane operators. By the end of October 2026, the SGF will provide the final clarity required for determining 2025 offsetting requirements. At the same time, the rigour applied to ongoing 2026 monitoring activities will directly influence the efficiency and outcome of the final Phase 1 verification process in 2027. 

Aeroplane operators that maintain a “Verification-Ready” approach throughout 2026, including robust monitoring, data integrity checks, internal controls, and timely record management, will be better positioned to meet both CORSIA offsetting and reporting obligations as the scheme transitions into its Second Phase. 

References

1. ICAO (2026). Annex 16 to the Convention on International Civil Aviation, Environmental Protection — Volume IV. 2nd Edition.
2. ICAO Council (2025). CORSIA Sectoral Growth Factor (SGF) Publication Schedule for the First Phase.
3. UNFCCC (2026). Article 6 Implementation Progress Report: Corresponding Adjustments and International Transfer of Mitigation Outcomes (ITMOs).
4. IATA (2026). CORSIA 2026 Monitoring and Reporting Guidance for Member Airlines.
5. Verra/Gold Standard (2026). Joint Statement on ICAO-Eligible Unit Supply and Corresponding Adjustments.