I'm a non-EU master student in Germany and confused as hell. I was just able to get my work permit (little green document stating what's allowed for me to do) changed to allow freelancing for certain clients. This was possible after I got a letter from my Hochschule explaining to the Stadtamt, that they see that my tasks fit my studies. My new work permit now explicitly mentions the client's names and that I may work with them on freelance basis. One of these clients, a rather large studio is asking for me to include my VAT ID number (USt-IdNr.) in my invoice. Looking into this, it seems you have to apply to that and it seems rather messy for someone not making large amounts of money. I am well under the taxable income bar. I've so far been successful with just including my Steuernummer (11 digit number) with other clients. Any thoughts/experiences/clues?