1 Summary The topic of this diploma thesis is taxation of companies' income. The aim of the thesis is to describe and introduce question following from the application of income tax act to the companies. The accent is put on the taxation of dividends. Taxation of companies' income plays a vital role in decision making process of domestic as well as foreign investors where to invest their finances. The thesis is focused on the analysis of Czech tax legislation made through a comparison with the Slovak basic tax legislation. The first chapter deals with the delimitation of core concepts related to the taxation of incomes. It focuses on the income tax act, aspect of natural person's taxation and artificial person's taxation. The second chapter is concerned of characteristic related to taxation of personal companies and stock corporations. The third chapter presents basic terms of dividend's taxation on the domestic as well as on the international level such as the core concept of dividend or tax domicile. The fourth chapter examine the European tax legislation and harmonization of tax legislation within the European Union. The fifth chapter illustrates taxation of domestic payment of dividends and its characteristics related to the natural and artificial person as recipients of dividends. The sixth chapter...