The rules on working depend on your nationality. More specifically whether you're a citizen of the EU/EEA or not. All international students working in the Netherlands must have Dutch public health insurance.
Free to work
Are you from the EU/EEA? Then you are free to work in the Netherlands. You can work for an employer or as a freelancer (self-employed). You don’t need a work permit.
Also, there are no restrictions on how many hours you work. But you do have to take out Dutch public health insurance.
Are you from outside the EU/EEA? Do you want to work during your studies? Your employer needs to apply for a work permit for you. The organization that arranges this is UWV.
Restrictions for work permit holders
Work permit holders can choose from 2 options. Option 1 is to work no more than 16 hours per week. Option 2 is to work full-time during the summer months of June, July and August. You cannot do both options!
All international students are free to do self-employed work in the Netherlands. You don’t need a work permit for this. Also, there are no restrictions on hours.
You can do self-employed work next to studying and next to a part-time job. To become self-employed, you need to register at the Dutch Chamber of Commerce (Kamer van Koophandel).
As an international student, you normally don’t have to take out Dutch health insurance. But as soon as you get a job, the situation changes. You are seen as an employee. Then you have to take out Dutch public health insurance.
It doesn’t matter whether you pay tax or how many hours you work. It also doesn’t matter if you are an EU citizen with an EU healthcare card. If you work in the Netherlands, you need to get Dutch public health insurance. If you don’t, you risk getting a big fine.
You have to pay income tax over your Dutch income. Scholarships may be included in your Dutch income. See the website of the Dutch tax office for more information.