In the Netherlands (and other countries), you have something called "leerplicht" or obligatory education law, and have to ask the school for permission.

The school is allowed to make an exemption for a maximum of 10 days, above that you need to contact the school attendance officer. This can only be provided if the reason falls under some specific types.

If you want to take your children on a holiday outside the national holidays, you have to provide proof that this only a possibility during term time.

You can read more about this at https://www.government.nl/topics/compulsory-school-attendanc...