The index rent is a variable rent for an object (dwelling, trade area). It is regulated in BGB "§ 557b.
The rent is therefore not durably certain to a fixed value, but on the basis of a basis rent, according to parameters comprehensible of both Contracting Parties is changed. Mostly the rent is coupled, published to the index of the cost of living by the Federal Statistical Office.
A condition for the validity with dwelling is that:
- the reference basis the price index for cost of living is published, by the Federal Statistical Office. ,
- the rent in each case for one year remains unchanged,
- the rent increase is made in each case valid in writing,
- the computation of the new demand for renting is revealed,
- is limited an increase because of modernization only in the cases, if the landlord were arranged by legal or behordliche editions to the modernization (e.g. for the observance of exhaust gas values)
- further rent increases according to the local comparative rent after BGB "§ 558 are impossible.
But different than in BGB "§ 558 intended no permission for the height of the computed increase is necessary also with dwelling. With trade area other base factors and shorter adjustment periods under reservation are permissible. Yardstick is that it does not concern a one-sided disadvantage debited to the tenant.
A variable rent with contractually fixed increase (e.g. with 4% increase per year) is not index separates a graduated rent.
In the comparison with the delimitation of a rent increase up to the local comparative rent after BGB "§558, otherwise planned for dwelling, the question arises, as cost of living or another base factor is in relation to the local comparative rent. This deviation is to be considered in the context of the valuation, since index rents might lead as particularly long-term put on to clear deviations between cost of living and thus the rent by the local comparative rent.
As a rule an index rent (e.g. by the influence of the particularly fast rising energy costs) might lie over the rent development, which is however yardstick for long-term value of a real estate. With application productive value procedure can in consideration of the possible tenant fluctuation a decrease be appropriate, or should from the beginning only to the local comparative rent be turned off.