Follow up to this question. Suppose a tenant were to write to the landlord that due to XYZ reasons, that they will reduce the rent they pay by X amount.
What is the legality of this exactly? Couldn't a renter very easily exploit this and cause a lot of legal headache for the landlord?
To have the right to pay less rent, you need to
If any of these points are not given, the reduction of rent (Mietminderung) is not legitimate, and you are liable for the full amount of rent. Remember, a reduction in rent is only allowed if there is a chance for the landlord to cure the problem after the initial disclosure of the problem to the landlord. The reasonable time depends on the nature of the problem: if the heating isn't working at all and the house is uninhabitable, the reasonable time can be 24 hours, if it is windows turning blind from bad glass, the reasonable time could be months. Typically, a non-emergency problem has about one week as a reasonable time. For missing energetic renovation, 3 months are prescribed. In that time, the landlord has time to fix the problem without it impacting the rent.
If the landlord deems that one of the points above is not true (e.g. the problem was caused by the tenant, the disclosure wasn't proper or timely, the problem is trivial, or they hadn't had a reasonable time and chance to fix it etc.) then the landlord is obligated to tell the tenant so in writing.
In case of dispute about if or in which amounts a reduction of rent is proper, then the courts will have to decide if or in which amount it is proper.
Not paying your rent without a proper reduction of rent or not fully paying it without a proper reduction gives rise to the landlord having the right to terminate the tenancy contract under § 543 (2) 3 BGB, as soon as the missing rent payments amount to two full months of rental fees. This includes reducing the rent more than reasonable, which would be the amount the court decides was allowed to be reduced. The termination without notice bypasses the normal notice time you have to solve your things and instead ends the tenancy at once. The next step would be for the landlord to sue to have the tenant evicted - which is a process that takes more than two months. The termination without notice can be voided by paying the outstanding rent within 2 months of the point the eviction lawsuit was started.
However, the extraordinary termination of the tenancy can be joined by a timely termination in the alternative under § 573 BGB. This termination persists even in case you cure your deficient payments. So even if you pay your outstanding rent, your tenancy will end after the relevant time is up from the point both terminations were delivered, and overstaying can result in eviction procedures, or resuming already started procedures.
Not paying your rent timely repeatedly also can give rise to termination under § 573 BGB.
To avoid the problem with termination, the full rent can be paid conditionally. That means the tenant protests the full amount but pays under the condition that the problem is fixed as soon as possible. It's usual, that in this case a court is looking into the proper amount of reduction of rent and any rent paid too much can be gotten back. However, the condition has to be declared properly.
It is best to inquire with the local Mieterverein on details of how to properly conduct a reduction of rent for problems with the flat. Besides the Tenant rights group, a lawyer might assist you.
