A letter asking you to agree to a higher rent is not a bill and not a decision — it is a request you are free to refuse. German tenancy law is unusually protective, and the formal requirements on a rent increase are strict enough that a meaningful share of these letters do not do what they claim to.
1. It needs your agreement
For an ordinary increase to the local comparative rent, the landlord cannot simply raise it. They must ask you to consent, and if you do not, they have to sue for that consent. The higher rent is not owed in the meantime.
This is the single most useful thing to know, because these letters are often written to sound like notifications of a change that has already happened. Paying the new amount can itself be treated as agreeing to it — so pay attention before you update your standing order.
2. How long you have to think
You get until the end of the second full calendar month after the demand arrives (§ 558b BGB). A letter arriving in March runs to the end of May.
That is a genuine consideration period, not a countdown to trouble — and it is usually long enough to have the letter checked properly. Work out your exact date here.
3. What a valid demand must contain
A demand has to be in text form, addressed to all tenants named on the contract, explain the new rent, and — the part that most often fails — justify it against the local comparative rent. Landlords normally do that by reference to one of:
- the local rent index (Mietspiegel);
- an expert's report;
- a rent database; or
- at least three comparable flats.
A letter that asserts a figure without a recognised basis, cites a Mietspiegel band the flat does not fall into, or arrives without being properly addressed to everyone on the lease may not start the clock at all. Errors here are common, and they are not something to eyeball — the comparison depends on size, condition, year of construction and location.
4. The ceilings a landlord cannot pass
Two separate limits apply on top of the justification requirement:
- The comparative rent itself. An increase cannot exceed what comparable local flats cost.
- The capping limit (Kappungsgrenze). Rent generally cannot rise by more than 20% within three years — reduced to 15% in areas with strained housing markets, which covers most large German cities. Separately, the rent must have been unchanged for at least twelve months before an increase takes effect.
Whether your city is designated as a strained market, and which Mietspiegel applies, are local questions — which is why a figure that is lawful in one city is not in the next.
5. Increases after renovation
A modernisation increase works differently: it follows building work that genuinely improves the property or saves energy, is announced in advance, and can be passed on to the rent within statutory limits per square metre.
The recurring dispute is the line between modernisation, which can be passed on, and maintenance — repairing what should have been working anyway — which cannot. Landlords have an incentive to describe the second as the first, and bills are frequently mixed. If you have received an increase following building works, the breakdown deserves scrutiny.
6. What happens if you say no
Nothing dramatic. If you do not consent, the landlord's route is to sue for consent within a further limited period. A court then decides whether the increase was justified — and if it was not, it does not take effect.
Withholding consent is a normal, lawful step, not a hostile act, and it is not grounds for terminating your tenancy. You can also consent in part, where the increase is justified up to a point but not to the figure claimed.
What you should not do is ignore the letter entirely and keep paying the new amount — that is the one route that concedes the point without anyone examining it.
7. What to do this week
- Note the date it arrived and calculate the end of your window.
- Do not change your standing order before you have decided.
- Check who it is addressed to — every tenant on the contract must be named.
- Find the justification and check it names a recognised basis.
- Dig out your contract and the last increase, if any — the twelve-month and capping rules depend on the history.
- Have it reviewed before the window closes. A defective demand is not binding, but only if someone spots the defect.
While you are at it
If a service-charge statement (Betriebskostenabrechnung) arrived recently too, that carries its own twelve-month objection period and its own high error rate. They are worth looking at together — same landlord, same paperwork, often the same mistakes.