This article addresses registration fees for same-sex unions and the number of registered gay couples in the German state of Baden-Württemberg. In contrast to the other 15 German states, in Baden-Württemberg each administrative district decides independently about the level of registration fees. Consequently, there is not only considerable variation of the number of registered gay couples across the individual administrative units, but also among the registration fees, which we seek to explain by relying on theories of public administration, policy analysis and political economy. Our findings show that the varying levels of registration fees for same-sex unions are primarily determined by the preferences of parties in the regional legislative committees. In this way, we can demonstrate that the definition of registration fees is politicised, which contradicts the legal principles of equivalency and cost recovery.