Navigating the Carbon Cliff: The Escalating Financial and Credit Risks of EU-ETS and CORSIA
March 31st 2026 marks the deadline date under EU ETS for airlines to submit their Annual Emission Report (AER) for 2025. A criticism of EU ETS and other climate policies such as CORSIA had been their very slow, gradual introductions, affording the aviation sector very generous exemptions and baseline buffers. However, this era of regulatory leniency is now abruptly ending. The combination of the phase-out of free EU ETS allowances, the looming threat that the EU will “restart the clock” on long-haul emissions (July 2026), and CORSIA entering its mandatory phase in 2027 mean that airlines are facing unprecedented operating compliance costs. The shockwaves will be felt throughout the broader aviation finance ecosystem, with lessors, banks and insurers facing a dramatic escalation in credit risk. As compliance costs multiply, understanding and tracking an airline’s precise carbon exposure is no longer just an ESG exercise; it is a fundamental pillar of financial risk management.
The EU-ETS Shockwave: The End of Free Allowances
Since the aviation sector was integrated into the EU ETS in 2012, airlines have benefited from a system that granted a significant portion of their emissions allowances for free. However, under the ambitious “Fit for 55” package, these free allowances are being systematically cut, culminating in full auctioning by 2026. This means that 100% of aviation allowances for in-scope flights must be purchased.
The financial implications of this policy shift are immense. The EU ETS operates on a “cap and trade” principle, setting a binding limit on total emissions that tightens annually. From 2026, this ‘cap’ is no longer in place with the removal of free allowances, and where there is demand the price of carbon is predicted to rise, with recent figures citing EU allowances costing between €70 to €90 per tonne. To put this into perspective, historical data for a European flag carrier shows compliance costs surging from €84 million in 2024 to an estimated €180 million by 2026.
Furthermore, the penalties for non-compliance are severe. Airlines that fail to surrender sufficient allowances face an emissions fine of €100 per tonne of CO2. Critically, paying this fine does not absolve the airline of its obligation; the missing allowances must still be purchased and surrendered.
The Sleeping Giant: ‘Stop the Clock’ and Route Exposure
While the phase-out of free allowances is a known quantity, a potentially more explosive financial risk lies in the EU’s “Stop the Clock” provision. Originally implemented in 2012 following severe diplomatic pressure, this derogation temporarily limited the scope of the EU ETS primarily to intra-EEA flights. This effectively allowed roughly 60% of the aviation sector’s total CO2 emissions to escape European regulation, resulting in an estimated 1.1 billion tonnes of unregulated CO2 between 2012 and 2023.
However, the most recent extension of this exemption expires on December 31, 2026. The European Commission is legally required to assess the environmental integrity of CORSIA by July 2026, and if it finds the scheme inadequate, a legislative proposal could extend the EU ETS scope to cover all departing international flights from the EEA. For international carriers, this represents a massive, overnight shift in financial liability. A flight departing Frankfurt for Hong Kong, or Paris to New York, which are currently out of scope for the EU ETS , would suddenly be in scope for EU ETS.
CORSIA’s Mandatory Era: 2027 and Beyond
Parallel to the tightening of the EU ETS, ICAO’s CORSIA is preparing to bare its teeth. CORSIA currently operates as an offsetting mechanism, focusing on capping net CO2 emissions at a defined baseline. For the First Phase (2024-2026), participation is voluntary, and the baseline is set at 85% of 2019 emission levels.
Starting in 2027, CORSIA enters its Second Phase, which makes participation mandatory for nearly all states globally. Unlike the EU ETS, an airline’s offsetting obligation under CORSIA is heavily influenced by the Sector Growth Factor (SGF)—a measure of how much global aviation emissions have grown compared to the CORSIA baseline. In 2024, international aviation produced about 15.948% more CO2 than the baseline, meaning that growth portion is used to calculate individual airline offsetting obligations.
Assessing the Impact: A Matrix of Financial Exposure
| Airline Profile | Current Regulatory Exposure (Pre-2026) | 2026 EU-ETS Impacts (Phase-Out & 'Stop the Clock') | 2027 CORSIA Impacts (Mandatory Phase) | Overall Financial/Credit Risk Level |
|---|---|---|---|---|
| Low Cost Carrier (Intra-EU flights only) | High EU-ETS exposure. CORSIA scope is superseded by EU-ETS to avoid double counting. | Severe: The "cap" is removed in 2026, forcing airlines to purchase allowances for 100% of their emissions. | Negligible direct impact. Routes remain heavily regulated by the more expensive EU-ETS. | Extremely High. Moving to 100% auctioning at ~€70+ per tonne will massively increase operating costs. |
| Regional Carrier (Majority Intra-EU, some Transatlantic) | Intra-EU flights are fully in EU-ETS scope. Transatlantic flights are currently exempt from EU-ETS. In scope for CORSIA MRV+Offsetting between participating states. | Severe: 100% auctioning for the intra-EU network. If 'Stop the Clock' ends, all transatlantic flights departing the EU will fall into EU-ETS. | If the EU restarts 'Stop the Clock', a portion of transatlantic emissions shifts from the cheaper CORSIA bucket to the expensive EU-ETS bucket. | Very High. Facing a potential "double hit" from the loss of free allowances and geographic scope expansion. |
| US-based Airline (Extra-EU flights only) | Out of scope for EU-ETS. In scope for CORSIA MRV+Offsetting between participating states. | High: If 'Stop the Clock' ends, all flights departing the EU for the US will immediately fall under EU-ETS. | If EU-ETS expands, non-EU airlines will suddenly see emissions shift from cheaper CORSIA offsets to expensive EU carbon credits. | Moderate to High. Highly dependent on the European Commission's 2026 'Stop the Clock' decision. |
| Middle East-based Airline (Extra-EU flights only) | Out of scope for EU-ETS. In scope for CORSIA MRV+Offsetting between participating states. | High: If 'Stop the Clock' ends, flights departing the EU for the Middle East will fall under full EU-ETS scope. | The 2027 Second Phase is mandatory for nearly all states. Any flights not swept up by an expanded EU-ETS will trigger CORSIA obligations. | Moderate to High. Risk of "Carbon Leakage" if passengers’ route through non-EU hubs to save money. |
| Low Cost Carrier (Intra-Asia flights only) | Completely out of scope for EU-ETS. Currently mostly "MRV Only" under CORSIA due to non-participating states. | None. | High: The 2027 mandatory phase will abruptly bring international intra-Asia flights into offsetting scope. | Moderate. Moving from zero offsetting costs to CORSIA offsetting costs, though CORSIA is currently much cheaper than ETS. |
| Low Cost Carrier (Intra-Latin America flights only) | Completely out of scope for EU-ETS. Currently mostly "MRV Only" as most of South America did not sign up for early phases. | None. | High: The 2027 mandatory phase will enforce offsetting obligations for international flights for the first time. | Moderate. Face brand new operational costs from CORSIA, even if they avoid EU-ETS entirely. |
| South American Airline (Extra-EU flights only) | Out of scope for EU-ETS. Currently "MRV Only" under CORSIA. | High: If 'Stop the Clock' ends, the flight leg departing the EU will fall under the expensive EU-ETS. | High: In 2027, the mandatory phase will force offsetting for the EU-bound leg. | High. Moving from an unregulated state to facing both expensive EU-ETS (potentially) and mandatory CORSIA offsets. |
Credit Risk: A Call to Action for Financiers and Lessors
Currently, a staggering 55% of global aviation emissions remain “Non-Regulated” by these mechanisms. However, as the 2026 and 2027 deadlines approach, the net is closing. The disparity in compliance costs is severe: purchasing carbon credits for 2.39 million tonnes of CO2 under the EU ETS would cost over €208 million, while the same volume under CORSIA costs approximately €59.8 million.
For aircraft lessors and aviation financiers, this dynamic fundamentally alters counterparty credit risk. A sudden, un-hedged spike in annual operating costs can rapidly erode an airline’s liquidity, directly impacting lease payment capabilities and debt service coverage ratios. Financiers must move beyond standard credit assessments and integrate granular, route-level carbon liability forecasting into their underwriting models. Without deep visibility into how an airline’s specific network interacts with the matrix of EU ETS, UK ETS, and CORSIA regulations, financial stakeholders are flying blind into a regulatory storm.
 | Paul Conroy Product Manager [email protected] |
