The purpose of the thesis is to compare the taxation of the employee income in the Czech Republic and in Ireland with appropriate legislation of 2015. In theoretical part, I describe tax system of both states with an emphasis on taxation of income from employment. The theoretical part contains also a short summary of tax systems development. Practical part is divided into two different sections. First of them is focused on the calculation of effective tax rate for taxpayers in different types of households and the second one deals with the calculation of interval and global progressivity of tax in both countries, together with an analysis of income equality or inequality in society by using the Lorenz curve and the Gini coefficient. The calculations showed a progressive tax effects in both the Czech Republic and Ireland, with higher rate of tax progression and higher degree of income inequality in Ireland. From the perspective of effective income tax rates, higher tax burden is imposed in Ireland. The effective tax rate is on average 13.5 of percentage points higher than in the Czech Republic. This is also confirmed by the legal provision of the relevant tax legislation.