<p>The 2019 property tax reform marks a turning point in tax policy within the German federal system. For the first time, the Länder were granted the authority to introduce their own property tax models through an opt-out clause, thereby deviating from the unified federal framework. Against this backdrop, the article examines why some Länder make use of this deviation competence and develop independent models, while others adopt the federal model. The analysis employs a fuzzy-set QCA approach and integrates theoretical perspectives on partisan differences, housing market structures, and fiscal capacity. The findings indicate that fiscally strong states with structurally strained housing markets are particularly likely to develop their own models, using the property tax as an additional instrument for housing policy steering—such as influencing housing costs or land consumption. In contrast, low fiscal capacity emerges as a necessary condition for adopting the federal model. The study thus highlights a typical pattern of German federalism, in which developments unfold along existing disparities between fiscally strong and weak states. At the same time, it becomes evident that the property tax reform not only responds to constitutional requirements but also opens a new chapter of federal autonomy and policy variance. However, it remains doubtful that the reform will settle the long-standing debate surrounding the tax. Rather, its integration into the existing fiscal equalization system is likely to generate further conflict potential.</p>