Germany is a nation of renters.
With 52.8 per cent of the population living in rented accommodation in 2025, more people rented their homes than in any other EU member state.
At the same time, for 11.2 % of the population, renting a home placed a financial strain on them. They had to spend more than 40 per cent of their disposable income on housing costs.
The probability is therefore high that you too have a tenancy agreement. And you are probably interested not only in what you are paying today, but also in whether and according to which rules your rent might change in the future.
For the parties can agree already upon conclusion of the tenancy agreement that the rent may increase or decrease later.
The law provides various options for this.
1. The index-linked rent
One of the legally provided options for adjusting the rent is the so-called indexed rent.
For her, the development of the rent is based on the Consumer Price Index of the Federal Statistical Office („CPI“).
Or as § 557b para. 1 BGB puts it: The contracting parties can agree in writing that the rent is determined by the price index for the cost of living of all private households in Germany as calculated by the Federal Statistical Office (index-linked rent).
A typical index-linked rent clause, for example, reads:
„The parties agree that the monthly rent shall be subject to value-linking from the start of the tenancy (base = index level at the start of the tenancy). If the monthly consumer price index for Germany determined by the Federal Statistical Office increases or decreases compared to the level at the start of the tenancy or the last rent determination, the rent shall change in accordance with the percentage deviation of the index that has occurred, calculated from the start of the tenancy or the last rent adjustment. The first rent adjustment under this provision shall take place one year after the start of the tenancy. Subsequent rent adjustments shall continue to take place one year after each implemented rent change. The rent shall be changed by means of a declaration in text form. The amended rent shall be payable from the beginning of the month after next following receipt of the declaration regarding the rent adjustment that has occurred.“
2. The index-linked rent does not automatically rise with the consumer price index
Pursuant to Section 557b(3) sentence 1 of the German Civil Code (BGB), the rent adjustment must be asserted by means of a declaration in text form.
This means for you: Your rent does not change simply because the Federal Statistical Office publishes a new CPI. The rent change must be explained to you in writing.
In this statement, the change in the price index that has occurred and the respective rent or the increase as a monetary amount must be specified in particular.
The changed rent is generally payable from the beginning of the month after next following receipt of the declaration.
Practical tip: Index-linked rent is not a one-way street. If the relevant CPI falls, tenants can also declare a rent reduction.
3. Time restriction period for index-linked rent increases
As part of an indexed rent, the rent may not be adjusted arbitrarily often.
In accordance with Section 557b paragraph 2, the rent must generally remain unchanged for at least one year while an index-linked rent is in effect.
That means for you: Between two rent increases based on the development of the CPI, the rent must generally remain unchanged for at least one year.
During the lockout period, only rent increases expressly permitted by law under Sections 559 to 560 of the German Civil Code (BGB) are possible under their respective regulated conditions (e.g. in the event of a change in operating costs).
Practical tip: You can, of course, agree a longer notice period with your landlord.
The waiting period is linked to the last effective fixing or amendment of the rent. The starting point can therefore not only be the beginning of the tenancy, but also a later (consensual) rent amendment.
4. Rent control applies only to the initial rent
Under § 557b para. 4 of the Civil Code (BGB), the provisions on the permissible rent at the start of the tenancy in areas with tight housing markets (so-called rent brake) generally only apply to the initial rent in the case of index-linked rent.
If an index-linked rent is validly agreed, subsequent adjustments to the development of the consumer price index are not limited again by the rent cap. The rent cap can therefore limit the rent amount at the beginning of the tenancy, but not every subsequent index adjustment.
5. Which index-linked rent agreements are invalid?
Not every agreement that calls itself an index-linked rent contains an effective indexation clause.
Section 557b(5) of the German Civil Code (BGB) establishes a clear limit here: any agreement that deviates from the statutory provisions of Section 557b BGB to the detriment of the tenant is void.
Therefore, a clause under which the rent automatically increases in line with changes in the consumer price index is invalid, for example. Rather, any adjustment of the rent requires the legally prescribed declaration in text form.
Equally, the tenancy agreement must not reserve the right to adjust the rent solely to the landlords. A so-called unilateral clause unfairly disadvantages the tenants.
The same applies to so-called minimum rent clauses. Such clauses are intended to prevent the rent from falling below an amount once reached, e.g. below the original starting rent or below a minimum amount stipulated in the contract. Such a provision also departs from the statutory provisions and the spirit and purpose of Section 557b of the German Civil Code (BGB) to the detriment of tenants.
Equally, the tenancy agreement cannot grant the landlord more extensive or frequent rent adjustment options than those provided for by law. The statutory blocking period is specifically intended to prevent the rent from being adjusted to changes in the consumer price index multiple times within a short period. Contractual structuring that seeks to bypass this statutory blocking period through a special arrangement may contravene the protective purpose of Section 557b of the German Civil Code (BGB).
Since residential tenancy agreements are frequently standard business terms, an agreed index-linked rent can also be subject to the transparency requirement of Section 307(1) sentence 2 of the German Civil Code (BGB).
If there is a lack of the requisite transparency, the clause may be invalid pursuant to Section 307(1) sentence 2 of the German Civil Code (BGB).
It must therefore be sufficiently clear to tenants which rights and obligations arise from the index clause and what economic consequences may be associated with it. Unclear or ambiguous provisions can lead to tenants not recognising their rights or refraining from enforcing them.
For example, a clause may be invalid if it does not make it clear that a rent increase pursuant to Section 559 of the German Civil Code (BGB) is only permissible under the statutory conditions of this provision. A mere reference within the index clause to the statutory provision is not necessarily sufficient. Rather, the decisive factor is whether the contractual regulation as a whole makes it sufficiently clear under what conditions and to what extent landlords can increase the rent.
6. Are index-linked rent clauses rent drivers?
The basic idea of index-linked rent sounds quite charming at first glance: if consumer prices rise, the rent can be adjusted accordingly. Conversely, if they fall, a reduction in the rent can also be demanded.
The index-linked rent thus appears to be a mechanism that ties the rent to an objectively measurable economic development. In times of sharply rising living costs, however, the downside of this model also becomes apparent.
The problem lies less in the fact that the rent can change than in what that change is linked to. The sole decisive factor is the change in the Consumer Price Index.
Thus, the rent follows a trend that initially has little to do with the individual tenancy agreement. If, for instance, prices for energy, food or other goods and services rise, this can lead to a higher rent even though nothing has changed about the flat itself. In this way, the general price level becomes the basis for an individual rent increase, without the tenants' specific financial situation or the development of the individual tenancy agreement playing any role.
This is precisely where the fundamental flaw of the index-linked rent lies. For a rent increase, inflation at the level of the cost of living is sufficient. The design does not take into account whether and to what extent tenants' incomes keep pace with the rising cost of living. The rent necessarily follows the price index; the tenants' incomes do not necessarily do so.
What was designed as a clear and predictable option for rent adjustment can therefore become a mechanism under conditions of high inflation that shifts a significant portion of the inflation risk onto tenants. Index-linked rent protects landlords from the loss of purchasing power of their rent. In return, the risk of currency devaluation is borne by the tenants.
The legislature now wants to respond to this development. According to a draft bill by the Federal Government, the possibility of index-linked rent increases in areas with tight housing markets is to be limited in future. If the consumer price index rises by more than three percent within a year, only half of the increase exceeding that amount is to be taken into account for the calculation of the rent increase.
However, this is still a bill. The planned limitation therefore does not currently apply. Until a possible new regulation, the previous legal requirements remain in place.
This post is for general information only and does not constitute legal advice. It cannot and is not intended to replace individual legal advice in specific cases. Every situation has particularities that may require a different legal assessment. To assess your personal situation and develop a solution tailored to your case, obtaining qualified legal advice is recommended.