Why the defect notice is indispensable
§ 536c BGB requires tenants to report a defect without delay as soon as it appears during the tenancy. “Without delay” (unverzüglich) means without culpable hesitation. No more than a few days should pass between discovery and notice.
Skipping the notice costs you twice. First the right to reduce the rent. Second, you can become liable for damages if the harm grows because nobody was told — for instance when a damp wall turns into a renovation case over time.
The reduction arises by operation of law. But you can only enforce it from the day the landlord knows about the defect. The date of your notice is therefore also the start date of your claim.
There is an exception: if the landlord already knows about the defect, because the caretaker saw it or the whole building is affected, the duty to report falls away. You still should not rely on it. A short letter costs little and settles every later question of proof.
These nine details belong in the defect notice
The most common mistake is a vague description. “There is mould in the bathroom” is not enough. Better: “On the north wall of the bathroom, above the shower, there has been mould growth of roughly 40 × 30 cm since 3 March 2026. The growth is black-green and there is a musty smell.”
- 1Sender: your full name and the address of the rented flat
- 2Recipient: name and address of the landlord or the property manager (Hausverwaltung)
- 3Date of the letter
- 4A subject line containing the word “Mängelanzeige” and identifying the flat (address, floor, flat number if any)
- 5A specific description of the defect: what exactly, in which room, since when, how does it show?
- 6A reference to your evidence: attached photos, temperature or noise logs, witnesses
- 7A demand to remedy the defect, with a deadline given as a specific date
- 8A statement that you are reducing the rent or paying under protest (unter Vorbehalt) until it is fixed
- 9Your signature
What deadline to set
Write a specific date into the deadline (“by 20 August 2026”), not a period such as “within two weeks”. Only a date makes the moment of expiry beyond dispute, and every further step is built on that date.
| Type of defect | Reasonable deadline | Examples |
|---|---|---|
| Emergency / health hazard | immediately to 24 hours | Heating failure in winter, complete power cut, the only toilet broken |
| Urgent defect | 3 to 7 days | Water damage, severe mould growth, a flat door that will not lock |
| Ordinary defect | 14 days | Draughty windows, a broken lift, a dripping tap |
| Minor defect | 3 to 4 weeks | A broken doorbell, a long wait for hot water, a damp cellar |
Template: defect notice to the landlord
[Your name / Ihr Name]
[Street and number / Straße und Hausnummer]
[Postcode, city / PLZ, Ort]
[City / Ort], [Date / Datum]
An
[Name of the landlord / property manager]
[Address / Anschrift]
Betreff: Mängelanzeige für die Wohnung [address, floor, flat number]
Sehr geehrte Damen und Herren,
(if you know the name: Sehr geehrte Frau [surname], /
Sehr geehrter Herr [surname],)
hiermit zeige ich Ihnen folgenden Mangel in der von mir gemieteten
Wohnung an:
[Describe the defect in German and precisely: what, in which room,
since when, how does it show?]
Als Nachweis füge ich diesem Schreiben [Fotos / ein Temperaturprotokoll /
ein Lärmprotokoll] bei.
Ich fordere Sie auf, den Mangel bis zum [specific date] zu beseitigen.
Bis zur vollständigen Beseitigung des Mangels werde ich die Miete
[um X % mindern → I will reduce by X % /
unter Vorbehalt in voller Höhe zahlen → I will pay in full under protest].
Sollte der Mangel nicht fristgerecht beseitigt werden, behalte ich mir
weitere rechtliche Schritte vor, insbesondere Schadensersatz gemäß
§ 536a Abs. 1 BGB und die Selbstvornahme gemäß § 536a Abs. 2 BGB.
Mit freundlichen Grüßen
[Signature / Unterschrift]
[Name]
Anlagen:
- [Photos of the defect / Fotos vom Mangel]
- [Log / Protokoll]How to serve the notice so you can prove it
The law prescribes no form for the defect notice; in theory speaking would do. That helps you little when a dispute turns on proving that and when the landlord received it. Which is why the method of delivery matters.
- Einwurf-Einschreiben (registered post with documented delivery into the letterbox): a good balance of proof and cost, and the delivery record is available online
- A messenger with a witness: someone reads the letter, posts it and can later testify to both. Costs nothing and holds up in court.
- Handing it over in person against a written receipt: the safest route if the landlord cooperates
- Übergabe-Einschreiben (registered post against signature): risky, because the recipient can refuse it and the letter then counts as never delivered
- Email only: too little on its own, because delivery is almost impossible to establish
From practice: send the notice by email as well, so it lands on the desk at once. For proof, though, what counts is the postal route.
What happens after the notice
- 1The landlord inspects the defect and arranges the repair. Looking at it first is his right.
- 2You must allow access for inspection and repair once it has been announced. Refusing can cost you your right to reduce the rent.
- 3From the moment the notice arrives the rent is reduced by operation of law. If in doubt, keep paying under protest for now.
- 4If the deadline passes without result, damages under § 536a Abs. 1 BGB and self-remedy under § 536a Abs. 2 BGB come into play.
- 5Once the defect is fixed, the reduction ends. From that day the full rent is due again.
Frequently asked questions
Does the defect notice have to be in writing?
Written form is not required; the notice would be valid even spoken. But in a dispute you have to prove it reached the landlord. In practice there is therefore no way around a letter, served by Einwurf-Einschreiben or by a messenger with a witness.
How quickly do I have to report a defect?
Without delay, says § 536c BGB, meaning without culpable hesitation. In practice: within a few days of noticing it. Water damage and similarly urgent cases are best reported the same day.
Can I report several defects in one notice?
Yes, and it is sensible to do so. Describe each defect in its own paragraph with the room, when it started and how bad it is. That keeps the notice readable and lets you add up the reduction rates of the individual defects.
What happens if I do not report the defect?
As a rule you lose the right to reduce the rent for the period before the notice. It can get worse: if the damage grows because the landlord did not know, you may be liable for it (§ 536c Abs. 2 BGB).
Create a defect notice in 3 minutes
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Start now for freeMore guides
- Calculating a rent reduction: formula, examples and the basis of calculation
- Paying rent under protest: the safe route to a rent reduction
- Retroactive rent reduction: when you can get money back
- When a rent reduction is excluded: 7 grounds
- The 10 most common mistakes in reducing rent
- Serving a defect notice: email, letter or registered post?
- The landlord is not responding to the defect notice: what you can do now
This article provides general information and does not constitute legal advice (Rechtsberatung). Despite careful research, no guarantee can be given for accuracy, completeness or timeliness. For specific legal questions, contact a tenants' association (Mieterverein) or a lawyer specialising in rental law.