I have tried streaming a bit in the last seven days and find it really entertaining. I also found out about the legal aspects and what has to be considered. So I'd rather ask here again just to be sure.
My questions:
Do Twitch Donations have to be taxed (with no actual profit intention)?
Do you have to register a business from affiliate status? (Affiliate: 50 followers)
Do you need a broadcast license (like Gronkh or PietSmiet)?
What else do you have to consider when streaming (from the age of 14) (legal issues, etc.)?
Twitch donations are revenue and must be taxed / stated in the tax return.
A business must be registered from the point in time when the intention to make a profit, i.e. From the point in time at which one decides to pursue an activity that is supposed to bring in recurring / long-term money.
A broadcast license is required if you regularly provide planned content to a larger number of viewers. As long as you don't have regular broadcasting dates and a large number of viewers, the topic need not concern you. Channels with an average of less than 20,000 views, primarily LetsPlay content and without journalistic depth are mostly exempt from the regulation.
Since you can't start a business as a minor, business registration and income would have to be handled by a legal guardian.
To be honest, I would stop streaming or at least do without the donations.
From a tax point of view, the intention to generate profits is a decision on a case-by-case basis, and one would also have to differentiate between commercial operations and self-employment. In addition, you can assume that income is usually taxed (there are of course always exceptions).
Limearts has already explained the part with the broadcast license.
Since you are probably not of legal age, your parents (or legal representatives) would have to register your business, represent you in all matters and also vouch for you (e.g. In the event of errors in your tax return).
Now you have to weigh up whether this is still worthwhile, because opening a business or self-employed activity is not simply done overnight.
I do not want to give you any legal help here, but I would ask you if you really want to do this, talk to your parents and, if necessary, seek out someone who is familiar with something like this.