Someone Who Has Actual Knowledge of the German "Church Tax"

Very interesting stuff about the way the Church tax is administered and the truth about the ontological reach of a Catholic opting out of the paying of such, in the combox at Catholic Herald

As someone who grew up in Germany I may be able to give some background information:
In order to no longer pay 'Kirchensteuer' you have to declare at the local council that you leave the 'Catholic Church.' Since the goverment is no religious institution this means that one is leaving the civil-law corporation 'Catholic Church in Germany,' without any deeper religious meaning (and courts have made it clear that the goverment can only deal with civil law and have to leave everything else to the Church). The German bishops used to claim that this was tantamount to Apostasy, but a few years ago Rome told them that this was not the case. As a result, the German bishops introduced the crime of leaving the civil corporation, which is to be punished with de-facto Interdict - and recently the bishops decided that you can be teacher in a Catholic school if you live in a civil-partnership with some same-sex partner, but that you are sacked more or less automatically for the sin of de-registering from the civil-law coporation. (Oddly enough, foreigners moving to Germany and simply not registering to the civil-law corporation can receive the sacraments).
However, I guess that the tide is changing - if the German bishops join some Kasperite heresy (as most of them are likely to do so, although hopefully not all), many orthodox Catholics will refuse to fund them any longer, and it is hard to imagine that orthodox priests will pay any attention to this register any longer (it may be necessary to get married abroad, though, because there could be problems with the paperwork). I have been already taught by an long-standing German parish priest that de-registering was maybe not yet morally necessary (this was Pre-Synod) but would in his eyes not be a problem either.
The real tragedy is that the German Church could have done so many things with this money, but they use it to build up a giant administration and to dilute the Faith....