If CO₂ is sourced from the production or combustion of biofuels, bioliquids or biomass fuels, what certification approach should be applied in order for the CO₂ to be eligible for emissions from existing use or fate credits? 

The RED-compliant (ISCC EU) biofuel plant should be certified under two scopes: (i) Processing Unit for the biofuel/biomass fuel activity and (ii) Point of Origin for the CO₂ source. This reflects, first, the certified production of the underlying RED-compliant fuel and, second, the certified identification of the source of the CO₂ stream. The CO₂ is then transferred to the next certified element in the supply chain via a Sustainability Declaration. If the CO₂ is subsequently purified, compressed or liquefied in a separate installation, that installation must also be certified as a Processing Unit - Liquefaction, also under ISCC EU.