In Germany several different types of social contribution as well as taxes are deducted straight from your earnings. The rules for students are, however, often generous. You pay either lower contributions or none at all.
Every employee in Germany has to pay taxes. The amount depends on your income.
If you have a so called "mini-job" earning 450 Euro per month, you do not have to pay taxes.
If you earn less than 8,130 Euro a year you will get back the taxes you have paid at the end of the year if you submit an income tax return to the tax authorities.
All employees in Germany must make a contribution from their earnings to the state pension scheme. Usually this amounts to 9.45% of income.
Student contributions are normally lower.
An income up to 450 Euro is exempted from contribution. With an income of between 450 and 850 Euro per month or more than 20 working hours per week the amount is reduced. Whoever earns more, pays higher contributions. As of an income of 850 Euro per month students pay the full share of 9.45 %.
Even if they have a side job students are usually insured as students and not as employees. In that case they do not have to make any income related contributions towards health insurance. Under some circumstances, if they work more than 20 hours a week, students have to pay a contribution to health insurance. Clarify this beforehand with your employer!
Students do not normally pay unemployment insurance contributions. This means, though, that they cannot claim unemployment benefit if they lose their side job.