Index Rent: Protect Tenants in Germany 2025

As a tenant in Germany, index rent can suddenly increase your monthly burden. This article explains in plain terms how index rent works, which rights and obligations tenants have, and which deadlines apply. You will learn which forms and templates you can use, how to check calculations and which documents serve as evidence. We also show practical steps for communicating with the landlord, documenting increases and lodging a legally sound objection. The guidance is written so non-lawyers can apply it directly. For complex disputes we name the competent courts and relevant legal provisions so you can seek targeted further help. Read the concrete examples and templates; at the end you will find information on contact points and official forms.

What is index rent?

Index rent ties the rent amount to a price index; in Germany, the basic rules of tenancy law are set out in the BGB^[1]. With index rent, the rent rises or falls according to the development of the consumer price index. It is important whether your tenancy agreement contains a valid index clause and how precisely the adjustment formula is described.

How does it affect tenants?

Index rent can lead to predictable but also noticeable increases. Tenants should check whether the calculation is correct, whether formal requirements have been met and whether the adjustment matches the contractually agreed procedure. In disputes over calculation or form, court proceedings may be necessary; proceedings are governed by the ZPO^[2].

Important steps for tenants

• Check the calculation of the increase based on the consumer price index and compare it with your tenancy agreement.
• Keep payment receipts, correspondence and photos as evidence.
• Respond within the specified deadline and note all dates and deadlines carefully.
• Use template letters for formal objections or terminations and send important letters with proof of delivery.

Forms and templates

Important official templates help with formal steps. Examples of relevant forms and how to use them:

• Termination letter (BMJ template) — When: for your own termination or when you must terminate legally; Example: you terminate because of an invalid index clause and use the template as a basis for your letter.^[3]
• Objection letter (own template) — When: for formal rent increases or incorrect calculations; Example: you explain in writing which items you dispute and request a corrected statement.
• Default summons / court forms (local court) — When: in case of non-payment or reclaiming overpaid rent; Example: you apply for a default summons or file a claim with the competent local court.

Courts and contact points

In tenancy disputes, local courts (Amtsgerichte) are usually competent in the first instance; appeals go to the regional court (Landgericht), and the BGH can be decisive for fundamental legal questions^[4]. Proceedings follow the ZPO; observe deadlines and secure evidence.

FAQ

Can the landlord change index rent unilaterally?

No, an index rent clause must be contractually agreed; the landlord cannot change the calculation without basis or contrary to the contract.

How do I calculate the new rent for index rent?

The calculation follows the contractually agreed formula, usually based on the consumer price index; check the base index, baseline value and formula for plausibility.

What if the increase is incorrect?

Collect evidence, send a reasoned objection to the landlord and, if necessary, prepare a lawsuit at the local court.

How-To

1. First check the tenancy agreement for a valid index clause and the exact adjustment formula.
2. Collect all payment receipts, statements and correspondence as proof.
3. Send a formal objection with reasons and a deadline to the landlord.
4. If no agreement is possible, prepare a claim at the competent local court.

Help and Support / Resources

• Federal Ministry of Justice and Consumer Protection (forms and legal guidance)
• Gesetze im Internet (BGB, ZPO)
• Federal Court of Justice (case law)

1. [1] Bürgerliches Gesetzbuch (BGB) — Gesetze im Internet
2. [2] Zivilprozessordnung (ZPO) — Gesetze im Internet
3. [3] Kündigungsschreiben Muster — Bundesministerium der Justiz
4. [4] Bundesgerichtshof — Entscheidungen und Informationen