Got a Mieterhöhung? Here's what your landlord can — and can't — actually demand.

What is a Mieterhöhung?

A Mieterhöhung is a written request from your landlord to raise your rent. In the typical case — without a Staffel- or Indexmietvertrag — the landlord cannot just declare a higher rent. They must ask for your consent (Zustimmung) and justify the increase with a recognized reference like the local Mietspiegel.

If you don't agree, the landlord cannot raise the rent unilaterally. They have to sue you in court for your consent — and they only win if the increase strictly meets the legal rules.

Three things every Mieterhöhung must have

1. Written form, addressed to all tenants on the contract. If only one of two named tenants receives it, the request is invalid.
2. A justification (Begründung) — usually a reference to the local Mietspiegel, three comparable apartments, an expert opinion, or a Mietdatenbank entry. Without a valid justification, you don't have to accept it.
3. The new rent and the start date. The new rent applies at the earliest from the third month after you receive the letter.

The legal limits — Vergleichsmiete, Kappungsgrenze, Mietpreisbremse

Three brakes apply at once, and the increase has to fit through all of them:

• Ortsübliche Vergleichsmiete — the new rent cannot exceed the local comparable rent shown in the Mietspiegel for similar apartments in your area.
• Kappungsgrenze — within any 3-year period, your rent cannot rise by more than 20% nationwide, or 15% in cities with tight housing markets (most large German cities).
• Mietpreisbremse — for new tenancies in designated areas, rent cannot exceed the Vergleichsmiete by more than 10% at the start of a contract. This affects new contracts more than ongoing increases.

Your deadline: the Zustimmungsfrist

You have until the end of the second full calendar month after receiving the letter to respond. If the letter arrives in March, you have until 31 May to consent or refuse.

You can do one of three things:

1. Agree fully — the new rent applies from the third month after receipt.
2. Agree in part — you can consent only to the legally permissible portion. The landlord can sue for the rest if they think more is justified.
3. Refuse / stay silent — the landlord then has 3 months from the end of the Zustimmungsfrist to take you to court.

Silence is the default form of refusal. You don't need to write anything for the increase not to take effect — but writing a clear, polite refusal is recommended for the record.

When the letter is invalid

The letter does not bind you if any of these apply:

• It does not justify the increase (no Mietspiegel reference, no comparable apartments, no expert opinion).
• Less than 12 months have passed since the previous rent increase or the start of the tenancy. The Zwölfmonatsfrist must be observed.
• The 15-month rule is violated: the rent must have been at the current level for at least 15 months before the new rent takes effect.
• The new rent exceeds the Vergleichsmiete or the Kappungsgrenze.
• Not all named tenants are addressed.
• Modernization-based increases (Modernisierungsumlage) follow separate rules and limits.

Modernisierungsmieterhöhung is different

If the increase is justified by modernization (insulation, new windows, heating, lift), different rules apply: the landlord can pass on up to 8% of the modernization costs per year, capped at €2/m² over six years (€3/m² for higher rents). The letter must list each measure, the proportional cost, and the calculation. These letters are dense and frequently overstate what's allowed — read them carefully.

What to do — step by step

Step 1: Don't sign anything immediately. The Zustimmungsfrist gives you weeks. Use them.

Step 2: Check the form. Are all tenants named? Is there a justification? Is the new rent and start date stated?

Step 3: Look up the Mietspiegel for your city. Most German cities publish it online. Compare your apartment's size, year of construction, location, and equipment to the Mietspiegel range.

Step 4: Calculate the Kappungsgrenze. Take the rent from 3 years ago and add 15% (or 20% outside tight markets). The new rent cannot exceed that.

Step 5: Get help. Mieterverein membership (~€80/year) is the single best investment for tenants in Germany. They will check the letter for free and draft your reply. The Verbraucherzentrale also helps for a small fee.

Key terms glossary

Still not sure what your letter wants?

Upload your Mieterhöhung and get:

• ✓ Plain English explanation of the demanded increase
• ✓ Zustimmungsfrist and start-date deadlines extracted
• ✓ Quick check on form requirements and Kappungsgrenze
• ✓ Draft Zustimmung or Widerspruch letter in German

Open Briefed — explain my letter

Last updated: April 2026