What is the mortgage interest?
In case the interest fixed term is less than 10 years you can leave this field empty. According to the Dutch regulator AFM, in that case a fictive percentage of 5% shall be used in the calculation.
Exception: If the remaining mortgage duration is less than 10 years and the interest is fixed for this complete term, then you may calculate with the actual interest. In that case fill in your actual interest that you will be paying.