Stephanie R. Hoffer (Ohio State) has published Caesar as God’s Banker: Using Germany’s Church Tax as an Example of Non-Geographically Bounded Taxing Jurisdiction, 9 Wash. U. Global Stud. L. Rev. 595 (2010). Here is the abstract:

This Article compares the modern-day German church tax to church taxes levied by the American colonies and early states and concludes that, unlike its American counterparts, the German church tax is not wholly a “church” tax. Rather, it is primarily a form of decentralized local taxation, the jurisdiction of which is determined by voluntary group affinity rather than geography. As such, it is a crucial part of the German taxing landscape that should not be abandoned but should instead be retained and extended to qualifying secular organizations. In that context — secular rather than sectarian – the tax may also serve as the starting point for developing a model of non-geographically bounded jurisdictions to be used for funding local government or non-profit provision of public goods within the United States.