I don't think "fraud by accident" is possible. Fraud requires intent. Mistakes are just mistakes, and yeah you will have to pay back anything you shouldn't have

I don't think "fraud by accident" is possible. Fraud requires intent. Mistakes are just mistakes, and yeah you will have to pay back anything you shouldn't have received, and sometimes there are additional penalties, but fraud is something different. Then again, maybe the Netherlands doesn't distinguish between the two.