CORSIA and ISCC Explained: What SAF Needs to Count on International Flights From 2027

Passing engine tests is not enough for sustainable aviation fuel (SAF) to be recognised on international flights. The fuel must also meet the sustainability criteria of CORSIA, the International Civil Aviation Organization's (ICAO) carbon offsetting and reduction scheme for international aviation, and prove it through certification by an ICAO-approved scheme. Without that, airlines cannot claim emission reductions from the SAF they buy.

What is CORSIA?

CORSIA stands for the Carbon Offsetting and Reduction Scheme for International Aviation. According to IATA, governments agreed on the scheme in 2016, and ICAO adopted its standards as Annex 16, Volume IV, of the Chicago Convention on 27 June 2018. ICAO describes it as the first global market-based scheme to apply to a single sector.

In principle, airlines must offset growth in international aviation CO₂ emissions above a baseline. IATA notes that from 2024 until the scheme ends in 2035, the baseline is 85% of 2019 emissions. The phases are:

• Since 1 January 2019: operators emitting more than 10,000 tonnes of CO₂ a year must report their emissions.
• Pilot phase (from 2021) and first phase (2024–2026): offsetting applies only to flights between states that volunteer.
• From 2027 (second phase): all international flights become subject to offsetting, except routes to and from least developed countries, small island developing states, landlocked developing countries and states with a very small share of international traffic, unless they volunteer.

IATA reports that 130 states were participating as of 1 January 2026.

Where does SAF fit in?

According to ICAO, airlines can reduce their offsetting obligations by using CORSIA Eligible Fuel (CEF). There are two types: CORSIA sustainable aviation fuel, which is renewable or waste-derived, and CORSIA lower carbon aviation fuel, which is fossil-based. Both must meet the CORSIA Sustainability Criteria, the fourth edition of which was published in June 2025.

ICAO groups SAF feedstocks into main products, by-products, residues and wastes. The category affects how life-cycle emissions are calculated, using either ICAO's default life cycle emissions values or its methodology for calculating actual values.

The role of ISCC and other certification

ICAO requires fuel producers to be certified by a sustainability certification scheme approved by the ICAO Council. The list of approved schemes is set out in an official ICAO document and is updated over time; ICAO notes that Bonsucro was approved as a new scheme on 22 June 2026. In Indonesia, Pertamina uses ISCC (International Sustainability and Carbon Certification) under its CORSIA scheme for its SAF.

In practice, Pertamina says its SAF made from used cooking oil holds ISCC certification under CORSIA, covering oil collection, production at the Cilacap refinery and distribution. In September 2024, CNN Indonesia reported that Virgin Australia used used-cooking-oil SAF supplied by Pertamina at Bali's Ngurah Rai Airport, described as a CEF that can be claimed with ICAO. In August 2025, Pelita Air flew Jakarta–Bali on used-cooking-oil SAF co-processed at the Cilacap refinery.

Why feedstock matters

Not all bio-jet fuel automatically qualifies under CORSIA. Pertamina SVP Business Development Wisnu Medan Santoso, as quoted by iNews in September 2024, said bio-jet fuel from palm oil sources did not yet meet CORSIA requirements, making used cooking oil a more suitable alternative feedstock for international flights.

The issue is becoming more relevant because the Ministry of Transportation is targeting a 1% SAF blend from 2027, initially only for international flights from Soekarno-Hatta and I Gusti Ngurah Rai airports, according to Antara. Sokhib Al Rokhman, the ministry's Director of Airworthiness and Aircraft Operations, said timing depends on Pertamina's supply readiness. 2027 is also when CORSIA's second phase begins, covering more international flights.

In short, for biofuel producers, sustainability certification recognised by ICAO matters as much as technical specifications. Other biofuel terms are explained in the Media Biodiesel glossary.