Here are the most important things you should know about the student job:

1. You have to be a student, part- or full-time doesn’t matter. After your studies you won’t be able to work as Werkstudent anymore. Depending on your employer you could get a full-time job or continue your part-time job as a mini or midi job. Most of time your contract will come to an end simultaneously with each semester or it will be stipulated that the contract ends the moment the employee isn’t a student anymore.
2. You can work a maximum of 20 hours per week during the semester, but up to 40 hours per week during the lecture-free period. You can’t work more than 20 hours per week for more than 26 weeks each year. That is to make sure that you still have enough time for your studies.
3. You will get at least €12 per hour as that is the minimum salary (Mindestlohn). Depending on how many hours you work and your salary, the amount of tax and social security that will be deducted will vary. If you earn less than €520 per month please have a look at this article about the mini job, if you earn between €520 and €2.000 per month this article about the midi job will explain everything, and if you earn more than €2.000 per month this article about income tax and social security is going to answer all your questions.
4. If you get BAföG, you are allowed to earn up to €5.400 per year. If you earn more than that, it will be deducted from the amount you get as BAföG.
5. Depending on your employer, you will be able to make your own schedule. You can pretty much work whenever you want, making the student job easy to fit in any schedule.
6. Often, you will be able to get your student job credited as your compulsory internship. This is a real plus at can be really hard to find an internship that fits your schedule and your employers needs. If everything goes well with your student job, in a lot of cases, you will be able to write your Bachelor or Master thesis there.