The CAK says that you are not insured
If you have received a letter from the CAK to say that you are ‘not insured’, it means that you do not have health insurance with a Dutch health insurer. Dutch health insurance is compulsory for people who work in the Netherlands, or who are regarded as living in the Netherlands.
Take out health insurance
You must do this within 3 months. Otherwise you will get a fine from the CAK.