Let's say I have a website that gives information on electric guitars, but sells nothing. All income is generated via ads and affiliate programms. This income is of course subject to income tax.
Now one of those affiliate partners uses partner-points, which is basically in-store credit. If I "buy" a guitar for partner-points, is that guitar subject to income tax, too?
Note that this question is specific to Germany. If it makes any difference, I'm regularly employed, but do this on the side with my own one-man-firm (see comments for german definition).
I'm sure I left out a ton of relevant details, please let me know if you should need more information.