The successive transition to downstream taxation in German tax law results in under- rather than double taxation of public pensions. This holds true if special expenses induced by social security payments are assigned to pension insurance payments and received pensions respectively following the approach of the „Rürup Commission“ and the legislator. The extent of under-taxation is determined by both the expected development of pensions and the applied benchmark. Using the benchmark employed by the jurisdiction and the vast majority of the literature indicates an under-taxation of 11.4 % whereas a „systematic“ benchmarking provides a value of 8.4 %. Under-taxation of public pensions could be reduced significantly without causing double taxation issues if the taxation of public pensions was increased appropriately. This new system would not have to be adjusted to changes in expected pensions if it was based on the systematic benchmark. In contrast, using the „jurisdiction/literature“ benchmark requires a permanent modification of the tax system in case of a variation of expected pensions.