A Rent Increase Letter Landed in Berlin? What Section 558 and the Kappungsgrenze Actually Allow
A rent increase letter for an existing Berlin tenancy is not automatically valid just because it arrived on official-looking paper. Under Section 558 BGB, your landlord can only request consent to raise the rent up to your full local comparative rent, the ortsübliche Vergleichsmiete from the Berliner Mietspiegel, and only once your rent has already sat unchanged for at least 15 months, with a real justification behind it: comparable apartments, an official expert report, or the Mietspiegel itself. Even a correctly justified request still has to respect Berlin's Kappungsgrenze, currently a reduced 15 percent over any rolling three years rather than the national default of 20 percent, fixed by the city's own Kappungsgrenzenverordnung and valid through 10 May 2028 because the Senate has declared the entire city a strained housing market. The Mietspiegel 2026, published 28 May 2026 with a citywide median of 7.71 EUR per square meter across 189 rent categories, is the yardstick both sides use to find your specific comparative rent, and you can look it up for free through the official Mietspiegelabfrage on mietspiegel.berlin.de. You then have until the end of the second calendar month after receiving the letter to respond in writing, full consent, partial consent, or a reasoned refusal, and if you don't fully agree, your landlord has to sue for the rest within three further months or the whole request simply falls away.
The Official Rule
An envelope from your landlord with a new number and a signature line can feel like something you’re simply supposed to accept. German tenancy law disagrees, and in Berlin specifically, it hands you a fairly clear checklist before you sign anything.
Under Section 558 BGB, your landlord can only request your consent to raise the rent on an existing tenancy up to the local comparative rent, the ortsübliche Vergleichsmiete, and only once your current rent has already stayed unchanged for at least 15 months at the point the increase is meant to take effect. The request itself can be sent earliest 12 months after your last rent increase took effect, and it has to carry a real justification, not just a number: citing at least three comparable apartments, a paid expert appraisal, or the Berliner Mietspiegel.
| Limit | What it means for your rent |
|---|---|
| Local comparative rent (Mietspiegel) | The increase can go up to, but never past, 100% of your apartment's Mietspiegel category value |
| Kappungsgrenze (15%, rolling 3 years) | Even a fully Mietspiegel-justified request still can't raise your rent more than 15% above what you paid 3 years ago |
| 15-month rule | Your rent must have already been unchanged for 15 months by the date the increase would take effect |
| Missing or wrong justification | No comparable flats, expert report, or Mietspiegel citation, or the wrong Mietspiegelzeile, makes the request formally invalid |
This is a genuinely different mechanism from the Mietpreisbremse that caps a new lease. Signing a fresh contract in Berlin caps the rent at 10 percent over the comparative rent. An increase on a tenancy you already hold works differently: your landlord can ask for the full comparative rent, not just 110 percent of it, but the separate Kappungsgrenze then steps in as a hard ceiling of its own. Whichever number is lower, the Mietspiegel value or the 15 percent cap, wins in your favor.
Berlin’s Kappungsgrenze itself is set by the city’s own Kappungsgrenzenverordnung, issued under Section 558 Abs. 3 BGB. Because the Senate has declared the entire city an area where adequate housing at reasonable terms is particularly endangered, the cap sits at a reduced 15 percent over any rolling three-year window rather than the national default of 20 percent. The current version of the regulation was extended before its predecessor expired in May 2023 and now runs through 10 May 2028.
The comparative rent your landlord has to work from comes from the Berliner Mietspiegel 2026, published by the Senatsverwaltung für Stadtentwicklung, Bauen und Wohnen on 28 May 2026. It sorts roughly 1.6 million Mietspiegel-relevant apartments into 189 individual rows, or Mietspiegelzeilen, based on size, construction period, and features, and puts the citywide median at 7.71 EUR per square meter net cold rent, up about 7 percent from 7.21 EUR in the 2024 edition. This is the same Mietspiegel used for the Mietpreisbremse on new leases, but here it defines the increase ceiling directly rather than feeding into a 110 percent formula.
You can find your own Mietspiegelzeile for free. The official Mietspiegelabfrage on mietspiegel.berlin.de walks you through your address, your apartment’s Wohnlage (simple, medium, or good location), size, age, and features to return the specific value your landlord should be working from. If the arithmetic still feels uncertain, the Berliner Mieterverein, one of the city’s tenant associations, runs its own annual Mieterhöhung-Fragebogen, a form built specifically around the 2026 Mietspiegel’s 189 categories, for members to submit their increase letter for review. Membership starts around 7.50 EUR to join plus roughly 11 EUR a month, with a reduced rate near 6.50 EUR a month for lower incomes, and it includes legal protection cover for tenancy disputes, not just the rent check itself.
Your response has a real deadline. Under Section 558b BGB, you have until the end of the second calendar month after you received the letter to answer, in writing. You don’t have to accept or reject the whole thing outright: a partial consent, agreeing only to the portion that’s actually within the Mietspiegel and the Kappungsgrenze while explicitly withholding consent for the rest, is one of the more effective moves available to you, since it puts the burden of proving the remainder back on your landlord. If you withhold consent and hear nothing further, that’s not the end of it either: your landlord then has exactly three more months to file a Zustimmungsklage, a lawsuit asking a court to order your consent, and if that filing deadline passes too, the whole increase request simply lapses and would have to start over from a new letter.
What Real People Say
Berlin’s tenant associations describe rent increase disputes as an area that’s grown noticeably busier in 2026, driven less by dramatic one-off cases and more by the widening gap between what long-standing tenants pay and what apartments now list for on the open market, which gives landlords a stronger incentive to push existing rents upward wherever the Mietspiegel and the Kappungsgrenze allow it. Mietervereinigung Berlin, one of the city’s several tenant organizations, notes that the disputes it now handles tend to hinge on specific technical points rather than whether an increase is allowed in principle at all: whether the apartment landed in the right Mietspiegel row, whether the living space figure on the increase letter actually matches the lease, and whether a modernization cost got folded into the base rent instead of billed separately.
People who’ve been through the Berliner Mieterverein’s own review process describe the value less in dramatic reductions and more in confidence: knowing before you respond whether the number in front of you is defensible, rather than guessing. The recurring piece of advice across Berlin’s tenant community is consistent regardless of which association someone used: keep paying your existing rent, put your response in writing before the deadline, and don’t assume silence protects you, since the clock keeps running either way.
Step by Step
- Check the timing first. Has your rent actually been unchanged for 15 months, and did the last increase take effect at least 12 months before this letter arrived?
- Identify the justification and find your Mietspiegelzeile using the official Mietspiegelabfrage on mietspiegel.berlin.de, based on your apartment’s size, age, features, and Wohnlage.
- Compare the requested rent against both ceilings: your Mietspiegel category value, and 15 percent above what you paid three years before the increase takes effect. Whichever is lower is what actually applies.
- If anything looks off, get a second opinion from the Mietspiegelabfrage’s own result or, as a Berliner Mieterverein member, its Mieterhöhung-Fragebogen review.
- Respond in writing before the end of the second calendar month after receipt, full consent, partial consent to the correct portion, or a reasoned refusal, and keep paying your existing rent until you’ve actually agreed to more.
Compliance Note
This page explains the general rules around Mieterhöhung requests, the Kappungsgrenze, and the Mietspiegel 2026 in Berlin, but this is not legal advice, and the correct comparative rent for your specific apartment can only be confirmed through the official Mietspiegelabfrage or a tenant association.
FAQ & Common Pitfalls
Is Berlin's Kappungsgrenze actually stricter than Munich's?
No, not on the headline number. Both cities currently sit at 15 percent over a rolling three years rather than the national default of 20 percent. Berlin's reduced cap runs under its own Kappungsgrenzenverordnung, in force since the city declared itself a strained housing market, extended to run through 10 May 2028. Munich sits under Bavaria's own regulation, the Bayerische Mieterschutzverordnung, which was freshly reissued from 1 January 2026 through 31 December 2029 and now covers 285 municipalities across the state, Munich among them. Same percentage, different legal instrument, different validity window, and worth double-checking which one actually governs your address if you've moved between German cities.
How much can the increase actually ask for, does it also add 10 percent on top like a new lease?
No, and mixing this up with the Mietpreisbremse is a genuinely common mistake. That 10 percent buffer only applies when you sign a brand new lease. For an existing tenancy under Section 558, your landlord can request an increase all the way up to 100 percent of your local comparative rent, the full Mietspiegel value for your apartment's category, not 110 percent of it. The only ceiling on top of that is the Kappungsgrenze itself: whatever the Mietspiegel says, the increase still can't push your rent up more than 15 percent compared to what you were paying three years before the increase is meant to take effect.
What actually counts as a valid justification for the increase, and where do most letters go wrong?
Section 558a BGB requires the landlord to point to one of three things: at least three comparable apartments, a paid expert appraisal (Sachverständigengutachten), or the Berliner Mietspiegel itself, and to show the actual calculation, not just a demanded number. In practice, tenant associations say the recurring failure points sit in the details rather than the concept: an apartment slotted into the wrong one of the Mietspiegel's 189 rows because its size, age bracket, or feature score was misjudged, a living space (Wohnfläche) figure that doesn't match the lease, or a modernization surcharge folded into the base rent instead of billed separately under Section 559 BGB, which does not count toward the Kappungsgrenze at all.
What happens if I just ignore the letter or don't reply in time?
Silence is not consent, but it also isn't automatically a win. Under Section 558b BGB you have until the end of the second calendar month after the letter arrived to respond, in full, in part, or with a refusal, all in writing. If that window passes without your consent, the pressure shifts to your landlord: they then have exactly three further months to file a Zustimmungsklage, a lawsuit asking a court to order your consent, and if they let that deadline slip too, the entire increase request lapses on its own and they would have to start over from scratch. What you should not do in the meantime is start paying the higher amount before you've actually agreed to it, since doing so can be read as implied consent even without a signature.