Klartext Recht

Rent Increase Permissible? Everything About the Cap Limit & Local Rent Index

2026-06-11

Last Updated: June 2026
Reading Time: approx. 5 minutes

Legal Disclaimer: This article provides legal information based on the German Civil Code (BGB). It does not constitute legal advice. If you doubt the legality of a rent increase, you should consult a tenants' association or a specialized lawyer.

Rent Increase Permissible? Cap Limit and Comparative Rent Explained

A rent increase is a cause for concern for many tenants. But landlords are not allowed to arbitrarily raise the rent at their own discretion. German tenancy law sets limits here to maintain a balanced relationship between owner interests and tenant protection. Whether an increase is effective generally depends, among other things, on the local comparative rent and the statutory cap limit. You can find more basics in our tenancy law guide.

1. The Legal Basis: Increase up to the Comparative Rent (Section 558 BGB)

Under certain conditions, the landlord can demand consent to an increase in rent if the rent has remained unchanged for 15 months. The following general conditions apply:

  • Local comparative rent: As a rule, the rent may not exceed the fees agreed upon in the municipality for comparable living space over the last six years.
  • One-year deadline: The request for an increase may be made no earlier than one year after the last rent change.
  • Justification: The landlord must justify the increase in writing, for example, using a qualified rent index, information from a rent database, or three comparable apartments.

2. The Protective Shield: The Cap Limit

Even if the local comparative rent is significantly higher, the landlord may generally not increase the rent limitlessly within three years:

  • Standard case: The rent may not increase by more than 20% within three years.
  • Reduction in metropolitan areas: In areas with a tight housing market, the state government can reduce the limit to 15% by decree.
  • Exception: These limits generally do not apply to a rent increase following modernization measures.

3. Formal Requirements for the Letter (Section 558a BGB)

A rent increase is tied to formal criteria. If these are missing, the letter raises significant questions regarding its effectiveness in the event of a dispute:

  • Text form: The increase must be transmitted to the tenant in text form (e.g., letter or email).
  • Declaration of consent: The landlord must ask the tenant to agree to the increase.
  • Deadlines: The tenant is entitled to a reflection period until the end of the second calendar month after receiving the letter.

4. Content Control and Transparency (Section 307 BGB)

Rental agreements often contain clauses intended to regulate future increases in advance. This is where the content control for standard contract terms under Section 307 BGB comes into play:

  • Provisions in rental agreements are invalid if they unreasonably disadvantage the tenant contrary to the requirements of good faith.
  • A disadvantage may exist if the clause is not clear and understandable (non-transparent).
  • Clauses are also invalid if they violate essential basic principles of the statutory regulation (such as statutory protection through the cap limit).

5. What Tenants Should Do

Check a rent increase letter carefully. Is the increase above the cap limit or above the local comparative rent? Is the justification incomplete? If the increase seems unjustified, you generally do not have to agree. In this case, the landlord would have to sue for consent, which is often unsuccessful with flawed letters.

Smart Preparation with AI Analysis

Structuring cap limits and comparing rent index data can be complex. Jurivo supports you in your preparation:

  • Structure Orientation: The AI helps you compare the letter for typical formal characteristics and necessary information within the framework of Section 558a BGB.
  • Cap Limit Overview: Get guidance on classifying whether the request for an increase complies with the usual 15% or 20% limits.
  • Clause Check: We help you classify whether your rental agreement has provisions that regularly raise questions regarding their admissibility within the meaning of Section 307 BGB.

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Status of Legislation: June 2026.