In theory one can say they use 25% of their bedroom or living room for work, and hope that the tax man is lenient enough to accept that. But then you also need to submit the floor plan or square footage measurements in order to get something deducted from your rent/utilities. And probably pay someone to do all this for you due to the huge number of caveats. German tax law truly is something else.

Completely favors the middle class that can afford to keep one room for 'work'. One wonders if starving artists can get some tax returns for their attic shoebox ateliers.