The carbon border adjustment mechanism (CBAM) leads not only to the expected environmental changes, but also to the transformation of market environment. The study estimates the losses of the oil refining sector from the introduction of CBAM for the export of oil products from Russia to the countries of the European Union. An approach to assess the impact of CBAM on the cost of oil products has been formed and the mechanisms of its impact on the economy of Russian oil refineries have been identified. The study was carried out on the basis of actual data on the volume of greenhouse gas emissions in accordance with the current rules of the European emissions trading system. Decomposition of assessments of the CBAM impact was carried out into direct and indirect effects, as well as the effect of adaptation. It is shown that with the introduction of the CBAM mechanism, the prices of oil products in the domestic market will be determined not only by the logistical factor, but also by the requirements for environmental friendliness of oil refining. The introduction of CBAM will have a significant impact on the economics of oil refining, including refineries that do not export to the EU. The total impact of CBAM on the economy of Russian oil refineries will be about 250 mln dollars.