Tax administration is essentially the handling of funds. However, money loses its value over time, which becomes particularly important in situations where the obliged entity defaults on payment. The tax administration legislation therefore contains a system of interest which, under certain conditions, is added to such a payment as an accessory. The aim of the paper will therefore be to explain the purpose of the individual interest payments under the Tax Procedural Code and the significance of the recent developments in the legislation, which have significantly changed the conditions for their generation and their amount.