Where do I find more information about the city tax (local tax, Ortstaxe)?

The city of Vienna made an overview of all the topics that have to be kept in mind if you want to rent out your apartment to tourists. Here you have all the contacts too. Just look at www.wien.gv.at/wirtschaft/standort/share-economy/privat-vermieten.html.

Also the Wiener Apartmentvermieter Vereinigung (Viennese Apartmentmanager Association) would be pleased to support you with all your questions about those topics. More about the WAVV you can find at www.wavv.at