The landlord or landlady may increase the rent, but to do so must submit a official form use. In it are clear reasons for the increase and the corresponding figures. If you do not agree with an increase, you have 30 days to object.
Before you oppose a rent increase or file a Reduction you should find out exactly how to proceed and what deadlines you have to meet. Seek advice first before acting rashly. You can find out where to obtain advice here.
If the Reference interest rate If the reference interest rate is lowered, you as a tenant have a legal right to a reduction of the rent. A table with the amount of the reference interest rate as well as further information can be found at here . Additional information on the reference interest rate is available here.