Due to the debt brake German states are generally not allowed to run deficits. However, transitory deviations from this general rule can be made in response to business cycle fluctuations. Thus, cyclical adjustment is relevant for German states, and here especially with tax revenues. The article compares several methods for cyclical adjustment, namely local linear trends, the HP-filter and the method applied in Rhineland-Palatinate. Further, the impact of changes in tax law and the impact of the tax official projections are discussed. Finally, a real-time trend smoother is proposed to improve planning reliability.