1.Each aircraft operator shall determine the annual CO₂ emissions from aviation activities by multiplying the annual consumption of each neat fuel (expressed in tonnes) by the respective emission factor.

For mixed aviation fuels, the aircraft operator shall determine the theoretical amount of each neat fuel from the total amount of that mixed aviation fuel and relevant composition data by applying the following:

(i) where a fuel contains biomass, the aircraft operator shall determine the biomass fraction in accordance with Article 54;

(ii) where a fuel contains an RFNBO, RCF or synthetic low-carbon fuel, the aircraft operator shall determine the RFNBO or RCF fraction or the synthetic low-carbon fraction in accordance with Article 54b;

(iii) where the RFNBO or RCF fraction or synthetic low-carbon fraction is not zero and where the aircraft operator wants to make use of zero-rating, the aircraft operator shall determine the zero-rated RFNBO or RCF fraction or the zero-rated synthetic low-carbon fraction in accordance with Article 54c;