On 10 April 2018, the Federal Constitutional Court ruled that the rules for valuing property for the German property tax in the former West German states were unconstitutional. It did not stop them at once. It gave the legislature until the end of 2019 to pass new rules. After that, the old rules could still apply für weitere fünf Jahre ab der Verkündung, längstens aber bis zum 31. Dezember 2024, for five more years from promulgation, but no later than 31 December 2024. The court explained that revaluing all property needed an extraordinary effort in time and staff. About 36 million properties had to be revalued. The new tax has been levied since 1 January 2025.