The Czech tax system has the typical characteristics of post-communist systems of taxation and social security: social security contributions are the dominant tax channel and in addition the public health insurance premiums are collected by seven public health insurance companies and redistributed between them. The most significant change since the 1993 tax reform has been the reduction of the corporate income tax rate from 45% to 19%. A Czech peculiarity involves the transition to the taxation of the super-gross wage from 2008; the last three Czech governments have included the departure from this type of taxation in their programs, but for all that it is apparent that there is still no concept which could replace the existing system with its numerous neoliberal elements. This paper analyses the linkage of the social insurance premiums to the respective social security branches in the interest of defining the area for the rational share of these contributions in the tax mix. We define four social taxation models in contemporary western countries to solve this problem: the liberal, Christian-democratic, social-democratic and neo-liberal models. Afterwards we define the space for personal and corporate income taxation. The Czech value added tax has a slightly above-average basic rate, so it would not be expedient to raise it as the OECD has advised us to do in response to the very high social security contributions. At the same time, it is also not desirable to reduce the taxation of wages and overall capital incomes.