Greening the tax system is one of the tools for achieving sustainable development. Domestic literature on the subject presents various suggestions for the improvement of the tax system in Poland. This paper attempts to make a general assessment of the extent of the Polish tax system environmental reform implemented between 2007 and 2021. The paper has a literary and empirical character. The empirical analysis was conducted using descriptive statistics methods. The assessment is mainly based on selected indicators: pro-ecological solutions in traditional taxes, the number of ecological taxes in the tax system, the fiscal efficiency of ecological taxes measured as a share in total tax revenues, and the economic importance of the examined taxes measured as a share in GDP. A comparative analysis of the national ecological levy system with the tax systems of EU countries was also conducted. A review of selected general taxes shows certain pro-environmental solutions but also solutions that seem controversial from the point of view of environmental protection and human life and that do not encourage entrepreneurs and consumers to be more environmentally friendly. A positive observation, on the other hand, was an increase in the number of environmental taxes and charges. However, these are still far less important from the economic and fiscal perspective compared to conventional taxes. The decarbonisation process of the economy and, the increase in public spending during the 2008 financial crisis and the crisis caused by the COVID-19 pandemic are not conducive to the greening of the tax system.