Designing a new EU carbon trading system can cut costs significantly. Europe is working on improving its carbon market to meet climate goals. By considering a second trading system for more sectors like buildings and transport, costs could drop by up to 61%. Presently, reaching the EU climate target of 55% could cost about 248.9 billion euros and reduce consumption by 2.8%. However, with the new system, costs can go down by 21.5% with the current budget split or up to 33% with the proposed split by the European Commission. If even more budget is allocated to buildings and transport, savings could reach 61.6%. Flexibility in trading systems could help achieve climate goals economically.