Check a Mieterhöhung: Is the rent increase legal? (2026)
Check a Mieterhöhung: Is the rent increase legal?
Three things: the 15-month period, the cap, and the justification.
You have until the end of the second calendar month after receipt to check and decide (§ 558b BGB). Miss any of the three and you need not consent.
§ 558b BGBIn 60 seconds
You need not consent at once: the period runs to the end of the second calendar month after the letter arrives (§ 558b BGB). A letter in March runs to 31 May.
The rent must have been unchanged for at least 15 months at the point the increase is to take effect; the request may come at the earliest a year after the last increase (§ 558 Abs. 1 BGB).
Over three years the rent may rise by at most 20%, and by 15% in areas with a tight housing market (§ 558 Abs. 3 BGB).
The landlord must prove the new rent: through the Mietspiegel, three comparable flats or an expert report (§ 558a BGB).
Silence is not consent, but it does not protect you: ignore the letter and the landlord can sue for consent.
What the law says
Where the tenant consents to the increase, they owe the higher rent from the start of the third calendar month after the request arrives. Where they do not consent by the end of the second calendar month after receipt, the landlord may sue for consent within a further three months. Working translation; the German original is the binding text.
Which increase follows which rule?
Not every increase runs under § 558 BGB. Check first which kind you have.
| Kind of increase | Legal basis | Does the cap apply? |
|---|---|---|
| Up to the local comparable rent | § 558 BGB | yes (20%, tight markets 15%) |
| Modernisation | § 559 BGB | no, its own limits |
| Stepped rent (agreed in advance) | § 557a BGB | no |
| Index rent (tied to consumer prices) | § 557b BGB | no |
Related: Reading and using the Mietspiegel and Checking the rent brake.
What it means for each side
- Note the date it arrived: your period runs from there.
- Compare the new rent with the rent three years ago.
- Check the comparable rent against the Mietspiegel.
- Answer within the period, consenting or objecting.
- Observe both waiting periods before making the request.
- Attach a permissible justification (§ 558a BGB).
- Calculate on the lower of the comparable rent and the cap.
- Let the consent period run.
Common mistakes
The period runs to the end of the second following month, use it.
It is not consent, but the landlord can sue for consent.
Even where the comparable rent looks observed, the increase can fail on the cap.
Different rules, different limits. And if you were going to move anyway, do not miss the special right to terminate (§ 561 BGB).
What to do next
Note the date of receipt and work out the consent period.
Check the 15-month period and the cap against the rent three years ago.
Measure the rent demanded against the Mietspiegel and check the justification is permissible.
Decide within the period: consent, object, or use the special right to terminate (§ 561 BGB).
Frequently asked questions
How often can the rent be increased?
A Mieterhöhung up to the ortsübliche Vergleichsmiete is only allowed if the rent has been unchanged for 15 months at the point the increase is meant to take effect (§ 558 Abs. 1 BGB). The request itself can be made at the earliest one year after the last increase. On top of that the Kappungsgrenze applies: no more than 20 % over three years, or 15 % in tight housing markets.
What is the Kappungsgrenze?
The Kappungsgrenze (cap on rent increases) limits how much the rent may rise within three years. To a maximum of 20 % (§ 558 Abs. 3 BGB). In areas with a tight housing market, the federal state can lower the cap to 15 % by ordinance. It applies regardless of how high the ortsübliche Vergleichsmiete is.
Do I have to consent to the Mieterhöhung?
You only have to consent if the increase is both formally and substantively lawful. You have until the end of the second calendar month after receipt of the letter to decide (Zustimmungsfrist, § 558b BGB). If you do not consent, the increase does not take effect automatically. The landlord would have to sue for consent.
What happens if I don't respond to the Mieterhöhung?
Silence does not count as consent (§ 558b BGB). If you do not respond, the old rent stands for now. The landlord can then only sue for consent (Zustimmungsklage); they cannot simply collect the higher rent. Even so, respond within the deadline to avoid a lawsuit.
Can I move out after a Mieterhöhung?
Yes. A Mieterhöhung under § 558 BGB gives you a Sonderkündigungsrecht (special right to terminate, § 561 BGB). You can terminate up to the end of the second month after receipt; the tenancy then ends at the close of the month after next, and the increase never takes effect.
Does the Kappungsgrenze also apply to Modernisierung or Staffelmiete?
No. The Kappungsgrenze and the 15-month rule apply to the increase up to the ortsübliche Vergleichsmiete under § 558 BGB. A Modernisierung surcharge (§ 559 BGB) and an agreed Staffelmiete or Indexmiete (§§ 557a, 557b BGB) follow their own rules and must be checked separately.
This page gives general information as at the date shown. It does not replace legal advice on an individual case.