As long as you are a student, you are entitled to a quota of 600 working hours each year. During these 600 hours, you only pay a "solidarity contribution" and not the regular social security contributions that a regular employee pays when working.
This solidarity contribution is 2.71% of your gross salary. By comparison, a regular employee pays 13.07% in social security contributions. Therefore, as a student employee, there is very little difference between your gross and net salary.
What if you work more than 600 hours?
You can work more than 600 hours, but in that case, you will have to pay the regular social security contributions of 13.07%. You will therefore receive less money than before.
What if I don't use all my hours?
You can choose not to work the full 600 hours. However, you cannot carry over unused hours to the following year. If you only work 400 hours this year, you cannot work 800 hours next year. Each year, you start with 600 hours, as long as you are a student.
Checking your hours
You can check your remaining hours via the Student@Work website or app. You need to log in with Itsme or your ID card.