An increase letter is not yet a duty to pay more. First identify the type: an increase to the local comparable rent, after modernisation or by a contractual Staffel/index rent — each with its own rules. For the most common case (to comparable rent) check three things: correct form with a Mietspiegel-based justification, the Kappungsgrenze and the one-year interval. Some increases fail already here.
Rent Increase: check the justification
Not every increase is valid. How to identify the type (comparable rent, modernisation, index), check the justification via the Mietspiegel and verify the cap (Kappungsgrenze) and the one-year interval.
✓ Verified: 20/07/2026
WHAT TO DO
› Details and tips
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Max recommends:
I compared the increase with the city Mietspiegel — it is often free online at the municipality. The landlord had set too high a comparable rent. Then I recalculated the cap from the rent three years ago: part of it exceeded 20%.
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Lea recommends:
An increase to comparable rent is a request for consent, not an order: it takes effect only with your consent or via a court, not automatically. Modernisation and index rent work differently — first identify the type of letter.
Useful Tools
- Verbraucherzentrale Legal
Consumer protection centres.
FREQUENTLY ASKED QUESTIONS
Can the landlord raise the rent whenever he wants? ▾
No. For an open-ended tenancy the increase to comparable rent is limited: at least 12 months must have passed since the last increase, and the rise over 3 years is capped by the Kappungsgrenze of 20% (15% in tight areas). Otherwise the increase is ineffective.
What is the Kappungsgrenze? ▾
The ceiling for the rise of an existing rent: over 3 years it may not rise by more than 20% (15% in areas set by the state), even if the local comparable rent is higher. This applies on top of the duty to justify the increase via the Mietspiegel.
How do I check the justification? ▾
An increase to comparable rent must rely on evidence: the local Mietspiegel, at least three comparable flats or an expert report. Without a correct justification the request for consent is ineffective and can be rejected.