In 2023, the European Commission proposed a new climate policy instrument, complementing the emission allowance trading system in force from 2023. The carbon border adjustment mechanism (CBAM) aims to reduce carbon leakage from the EU to third countries and create equal economic conditions for domestic products and imported goods. On the other hand, the carbon duty is intended to put pressure on investments in low-emission technologies in developing countries. However, the implementation of a carbon border tax raises great concerns both from the point of view of international trade and the impact on the intra-EU economy. With respect to external markets, through prohibited protection of competition, the CBAM regulation may violate the principles of free trade within the WTO, and this mechanism also seems to be inconsistent with the principle of "common but differentiated responsibility" applicable in international environmental law. In addition to the external impact, the carbon duty may also affect the reconstruction of the trade structure within the EU, leading to a drastic drop in the value of imports. The article presents the essence of the CBAM regulation, the schedule for its implementation, the basic obligations of EU importers and the controversy that the title mechanism raises in relation to international trade policy.