The Dutch Healthcare system works with deductibles (eigen risico). This is the amount you yourself have to cover when receiving treatment. For example if your own risk is €385 and your received surgery cost €1000, you will be billed for €385 only and the rest is taken care of by your health insurance.
You can choose your own deductible level from a variety of options. Currently the lowest deductible is €385 but this can change every year. This government website provides more information about deductible levels (only in Dutch).
You can always chose to increase the level of your deductibles up to the point of €885. This is called a voluntary higher excess. If you do this, then you will have to pay that cost if you ever go to the hospital or have any treatment outside a family doctor’s office. Only do this if you are comfortable with the consequences. It is unlikely to be a good idea if you get injured often!