This diploma thesis analyses the suggestion of progressive tax rates for personal income tax, which was introduced in 2017 by Czech Social Democratic Party in its election program for election to the Chamber of Deputies of the Parliament of the Czech Republic. Progressive rates are designed to ensure higher tax progressivity and tax reduction for most taxpayers. Only people with salary above average would pay higher tax. Using indicators of progressivity and income inequality, the different impact of introducing progressive tax rates are examined. Progressive tax rates reduce overall income inequality in society, but disadvantage the low income group of tax payers and cause higher income inequalities between taxpayers with low and median in...