The proposal would reserve up to 110 million EU Allowances between 2028 and 2040 to cover part of the price differential between conventional fossil bunker fuels and eligible alternatives, with renewable fuels of non-biological origin (RFNBOs) covered at 90% of the price gap. All eligible fuels and technologies would draw from a single, non-ring-fenced pool, meaning e-fuels compete directly with biofuels and zero-emission propulsion technologies for the same allowances. The mechanism includes bonus percentage points for fuels produced from EU-sourced feedstocks, fuels from countries with linked emissions trading systems, and propulsion technologies installed in EU shipyards.