I did some reading.
Income from selling services counts as labour income, and the taxes is calculated accordingly. Over €200000 one month and the tax is 57%...
Income over €5400 from selling goods at one single time is taxed 30%, and it is payed after sending in the income tax return papers, or whatever you call it, at the end of the year.
So that part is actually the same here. Our financial year is split in may, and the result is presented in august or september somewhere for companies.
It's hard to have a small company and do all the paperwork yourself, so an accountant is often used. Saves a lot of time. Luckily I have no company, so my paperwork is very simplified. I just log in to my account with the tax office mobile app and press a button to sign.