The CNB’s June increase in the key interest rate to 3.75% will also affect the amount of tax-related interest from 1 July 2026, with an impact not only on default interest on late tax payments but also on compensation paid by the tax administrator to taxpayers.
Since 2021, default interest on late tax payments has been based on the CNB repo rate applicable on the first day of the relevant calendar half-year, increased by eight percentage points. For the second half of 2026, default interest therefore amounts to 11.75% p.a. If the tax administrator permits tax payment deferment, half of this rate applies.
Conversely, taxpayers can expect higher compensation where the tax administrator had failed to refund an overpayment on time or incorrectly assessed tax: in these cases too, following the increase in the repo rate, the interest rate will be 11.75% p.a. Half of this rate will apply to interest on VAT deductions if the tax administrator fails to pay it and the review lasts longer than four months from the deadline for filing the tax return.
We discuss the calculation of individual types of tax-related interest, as well as ways to reduce interest payable to the tax administrator, in more detail in our articles What interest to claim from tax administrator? and Default interest: how it arises and how to reduce it.