The German Federal Fiscal Court has reasonable doubts on the constitutionality of interest on tax payments for prior years starting from 2015 on. With decision of April 25, 2018 (IX B 21/18 the court has granted application for suspension. The decision is related to §§ 233a, 238 AO (German Fiscal Code). Interest on tax payments for prior years are charged by 0.5% per month of the tax payment which leads to an interest rate of 6.0% per anno.
Tax payers have to wait whether the decision leads to a change in legislation. For all open cases it is advisable to raise an objection and apply for an application of suspension with regard to the above mentioned decision.