Singapore’s aviation regulator, Civil Aviation Authority of Singapore (CAAS), will introduce a new “Sustainable Aviation Fuel (SAF) Levy” on flights departing Singapore starting in April 2026 (for bookings from that date) and applying to departures from 1 October 2026. The levy is designed to cover the expected premium cost of SAF needed to meet an initial 1 % blending target in 2026 and will be charged per passenger (and per-kilogram for cargo) with amounts varying by route distance and cabin class. For example, economy passengers flying from Singapore to Australia will pay S$3.30, while premium class travellers will pay S$13.21, and longer-haul premium flights (e.g., to Americas) face charges up to S$49.08.
The levy aims to align Singapore’s ambition as an international aviation hub with sustainability goals and the International Civil Aviation Organization (ICAO) target of net-zero aviation by 2050. However, the article also highlights questions around its effectiveness: the actual SAF supply remains constrained, the additional cost to passengers may be modest relative to the premium for low-carbon fuel, and Australia (one major destination) is watching the outcome closely as it has not yet adopted a mandated levy structure.
Every transition instrument, whether it is a SAF levy, a carbon tax, a green surcharge, or an ESG-linked fee, ultimately answers a single foundational question: who pays for climate action? In the case of Singapore, the policy forces us to confront whether a consumer-facing charge truly aligns with the Polluter Pays Principle (PPP), or whether it inadvertently weakens it. This is not a trivial distinction. The way we allocate costs today will determine whether sustainability becomes a shared societal transformation or merely another item on a traveller’s invoice.
Who is the Polluter?
If we apply a narrow interpretation of PPP, the answer seems obvious: the polluter is the person who chooses to fly, and therefore, asking the passenger to pay a levy appears entirely justified. After all, emissions are generated because travellers board aircraft and engage in carbon-intensive mobility.
But the aviation system is far more complex than a single transaction. Emissions arise from a multi-actor value chain where fuel producers, aircraft manufacturers, airlines, airports, and passengers each contribute to and profit from the activity that generates pollution. Fuel suppliers decide how jet fuel is refined. Aircraft manufacturers design aircraft that determine long-term efficiency. Airlines choose operational patterns and fleet structure. Airports provide the infrastructure that enables traffic growth. To frame the passenger as the sole polluter is to ignore the systemic or interconnected nature of aviation emissions.
A levy imposed only on travellers therefore shifts the burden downstream to the weakest actor in the value chain to those with the least structural control and the lowest ability to influence upstream decision-making. The “polluter” becomes the person with the least power, while those with the greatest capacity to decarbonise avoid any direct obligation.
Does the Singapore SAF Levy Align with PPP?
The answer is: only partially. The levy does internalise part of the emissions cost, and in that sense, it reflects an attempt to integrate environmental externalities into market decisions. But it does not structurally change the behaviour of the stakeholders who shape the aviation system. Fuel suppliers are not required to reduce refinery emissions or shift to low-carbon hydrogen. Airlines are not obligated to procure SAF beyond what the levy enables. Airports are not compelled to invest in SAF infrastructure. Governments are not committing long-term fiscal support for supply-side transformation. The levy therefore resembles a consumer-pays model, not a genuine polluter-pays mechanism.
When the Polluter Pays Principle Breaks Down
PPP becomes ineffective when three conditions arise.
First, the cost burden falls disproportionately on actors with limited influence such as passengers while upstream players remain insulated.
Second, the actors who shape most of the emissions footprint such as fuel suppliers, airlines, airports are not required to modify processes or inputs.
Third, the environmental outcome is modest relative to the cost imposed.
This risk is very real for SAF. If supply remains expensive and scarce, passengers will simply end up paying more without any meaningful reduction in aviation emissions. In such a scenario, PPP is not only weakened but it becomes symbolic rather than corrective.
What Would a True PPP-Aligned Model Look Like?
A more robust model would distribute costs proportionately across the entire aviation ecosystem. Fuel producers would face carbon-intensity obligations based on lifecycle assessments. Airlines would be required to adopt mandatory SAF blending targets and improve operational efficiency. Airports would co-finance the infrastructure needed for SAF storage and distribution. Governments would direct subsidies toward supply-side innovation, rather than pushing costs entirely onto consumers. Passengers would still pay a price signal, but one that reflects genuine discretionary travel rather than systemic pass-through.
PPP functions best when responsibility, capability, and control are aligned. A model that reflects this alignment is more equitable, more effective, and more likely to result in real emissions reductions.
The U.S. Sustainable Aviation Fuel Grand Challenge offers an instructive counterpoint. Its roadmap recognises that SAF scale-up cannot rely on a single cost-bearing actor: it sets coordinated targets for fuel suppliers, airlines, technology developers, and public agencies, backed by clear production milestones (3 billion gallons by 2030, 35 billion by 2050) and life-cycle performance thresholds. The initiative’s focus on upstream technology risk, feedstock constraints and supply-chain barriers underscores a critical point: meaningful transitions require systemic cost-sharing and multi-agency governance, not isolated levies. If anything, the U.S. example illustrates that SAF economics stabilise only when governments de-risk early investment, suppliers adopt lower-carbon pathways, and airlines commit to long-term off-take. A consumer-only model, such as a simple levy, lacks this structural depth.
Cost-Sharing Models for Sustainable Aviation Fuel
To advance the discussion, here is an expanded note outlining different cost-allocation architectures for scaling SAF in a manner consistent with the Polluter Pays Principle.
Model 1: Consumer-Pays (Singapore SAF Levy)
In this model, passengers pay a levy added to ticket prices to fund the SAF premium. It is simple to administer, provides transparent pricing, and ensures ring-fenced funds for SAF procurement. However, it places the entire burden on consumers while insulating upstream actors. Airlines and fuel suppliers can avoid meaningful responsibility, and if SAF supply remains constrained, the levy produces limited environmental benefit. This model offers low to moderate alignment with PPP.
Model 2: Airline Obligation Model (as seen in the EU)
Here, airlines are legally required to meet minimum SAF blending thresholds. This approach directly targets the operational entity responsible for emissions and creates stable demand for SAF producers. Airlines are incentivised to optimise efficiency. Yet if regulators do not control cost pass-through, airlines may simply shift all expenses to passengers. The model provides moderate to high PPP alignment, depending on how cost transfers are governed.
Model 3: Fuel Supplier Carbon-Intensity Standards
This model places decarbonisation responsibility upstream, requiring fuel suppliers to meet lifecycle carbon-intensity limits or purchase credits. It compels refiners to invest in cleaner processes and adopt LCA-based transparency. Verification is complex, and costs can migrate downstream, but the model targets the actors with the greatest technical control over emissions. It offers high PPP alignment when enforcement is rigorous.
Model 4: Low-Carbon Fuel Standard (LCFS)—California’s Approach
Under an LCFS, producers generate credits based on verified lifecycle performance, and aviation operators must purchase credits equivalent to fuel use. This structure is technology-neutral, rewards best-performing fuels, and stimulates rapid innovation. The main challenge is credit-market volatility, which requires strong governance. This model achieves very high alignment with PPP by incentivising low-carbon fuel production and consumption simultaneously.
Model 5: Shared-Responsibility Hybrid (Recommended)
The most equitable and effective model distributes costs across the system. Fuel producers face carbon thresholds. Airlines must meet mandatory blend requirements. Airports co-invest in SAF infrastructure. Governments provide targeted subsidies to stimulate supply. Passengers pay a modest residual levy that reflects discretionary choices rather than systemic vulnerabilities. This model reflects the actual distribution of responsibility and accelerates structural transformation rather than symbolic pricing. It provides the highest alignment with the Polluter Pays Principle.
Conclusion
A passenger levy may be a convenient first step, but it is not the embodiment of the Polluter Pays Principle. Sustainability cannot and should not be funded solely at the point of consumption. A true PPP-aligned approach requires a broad, coordinated, and proportionate sharing of responsibility across fuel suppliers, airlines, airports, governments, and travellers. Only such a hybrid model can deliver meaningful emissions reductions, ensure fairness, and create a transition that is both environmentally credible and socially durable.
The SAF debate sits within a much broader question that haunts SDG 12: in any transition toward sustainable production and consumption, who ultimately bears the cost of reducing environmental harm? Whether we look at plastic waste, fast fashion, food loss, or carbon-intensive supply chains, the pattern repeats. Costs tend to gravitate toward the actors with the least structural control on consumers, MSMEs, or informal workers while upstream producers, brands, and financiers face weaker incentives to change materials, processes, or business models. SDG 12 requires a redistribution of responsibility that matches capability and influence: producers internalizing life-cycle impacts, investors pricing externalities, governments correcting market failures, and consumers responding to fair price signals rather than absorbing disproportionate burdens. Without such alignment, sustainability becomes a transfer of cost rather than a transformation of systems.
(Image sourced from https://www.internationalairportreview.com/article/260177/sustainable-aviation-fuel-explained/)
