Today taxes play a very important role, provide financial resources to the state budget and ensure its proper functioning. Taxes are the most important source of state income. In order for the state to develop and fulfill basic obligations towards citizens, it must have financial means at its disposal. The tax system, as a collection of taxes in a given country, must be created in a clear and transparent way so as to facilitate taxpayers' actions. The tax must be set at an appropriate level so that it does not adversely affect taxpayers, and must also provide adequate resources to the state budget. Corporate income tax, on the one hand, is a burden and a barrier to the development of legal persons who run a business, but is also a source of state budget revenue. Corporate income tax was introduced in Poland along with the establishment of a free market economy. This is an income tax that does not take into account the minimum tax-free amount and does not differentiate tax entities. Corporate income tax in Poland has undergone a number of important transformations, especially after the accession of Poland to the European Union. Tax rates have been systematically reduced since the early 1990s. Corporate income tax should be particularly convenient for entrepreneurs, and should not act destructively because the number of entrepreneurs in the state determines the level of economic and industrial development. This is even more important since, after Poland's accession to the European Union, the transfer of a business to another EU member state no longer constitutes a problem. Attractive income tax also attracts foreign investors for whom the aspect related to easy accounting is vital. The aim of the publication is to discuss the issues related to the Polish corporate income tax i.e. tax management in an enterprise, the application of discounts and exemptions and also issues related to state income from corporate income tax and the income lost due to relief and dismissals. The paper also touches upon issues related to the construction of Polish corporate income tax, subject, object and the basis of this tax. It also covers the scale and rates of taxation, exemptions and reductions from corporate tax and a summary of the efficiency and favorability of entrepreneurs for the provisions of this tax. The work is based on a critical analysis of literature on the subject.