News on the prohibition of retroactivity in tax law

It is not uncommon for new tax laws to come into force with effect for the past. In its ruling of 24 February 2022 (III R 9/20), the BFH once again addressed the question of the constitutional limits of such retroactive effect. In his article, Michael Tischendorf examines the BFH decision against the background of the relevant case law of the Federal Constitutional Court and provides practical advice for the fiscal court proceedings. With a view to Section 4k of the German Income Tax Act (EStG), which was introduced retroactively from 2020 by the ATADUmsG of 25 June 2021, the topic is of undiminished relevance.