Mangelanzeige & Forcing a Repair: Tenant Rights 2026
Updated 6/14/2026 · HausMaus Redaktion
Your landlord must keep the flat in a contractually proper condition and fix defects (§ 535 Abs. 1 BGB). Report a Mangel (defect) without delay (§ 536c BGB) — that is the precondition for every further right you have. A significant Mangel reduces the rent automatically by operation of law from the moment the impairment begins (§ 536 BGB). Only repair it yourself if the landlord is in Verzug (default) or there is a genuine emergency (§ 536a Abs. 2 BGB).
A Mangel (defect) is any deviation from the contractually agreed condition of your flat that impairs its use — for example a broken heating system, mould, water damage or a leaking window. The most important point first: your landlord is legally obliged to keep the flat in a contractually proper condition for the whole tenancy and to fix defects (§ 535 Abs. 1 BGB). This claim is enforceable in court — you do not have to put up with a Mangel.
But before you reduce the rent, withhold payment or repair anything yourself, there is one mandatory first step: the Mangelanzeige (notice of defect). It is the precondition for nearly all of your further rights.
What do I have to do first?
Report the Mangel unverzüglich (without culpable delay), § 536c BGB in conjunction with § 121 BGB. No particular form is required — even a verbal notice is legally valid. For proof, however, you should always report in writing or in Textform (text form, e.g. email).
A good Mangelanzeige contains:
- a precise description of the defect and since when it has existed,
- photos or other evidence,
- a reasonable deadline for the repair,
- a request for a reply.
Why so quickly? If you do not report the Mangel (in time), you lose your rights to Mietminderung, damages and termination — to the extent the landlord could not remedy it because of the missing notice (§ 536c Abs. 2 BGB). Worse still: you can even be liable to the landlord for consequential damage, for example when an unreported small leak turns into a large one.
What deadline do I set for the repair?
The law names no fixed deadline — it only has to be reasonable, depending on urgency:
| Mangel | Reasonable deadline (guideline) |
|---|---|
| Ordinary defect (e.g. dripping tap, broken socket) | approx. 14 days |
| Heating or hot-water failure (cold season) | a few days / immediately |
| Acute danger (burst pipe, power outage) | immediately — emergency (§ 536a Abs. 2 Nr. 2 BGB) |
Set the deadline in writing and concretely, with a date. If the landlord does not react or lets the deadline pass, he falls into Verzug (default) — and that opens up your further options.
How much rent can I reduce?
As soon as a significant Mangel removes or reduces the flat's fitness for contractual use, the rent is reduced automatically by operation of law — from the moment the impairment begins (§ 536 BGB). You do not have to announce or declare the Mietminderung; you only need to have reported the Mangel (§ 536c BGB). Insignificant defects do not justify a reduction (§ 536 Abs. 1 S. 3 BGB).
By settled case law, the reference figure for the reduction is the Bruttomiete (gross/warm rent) — not the Kaltmiete (net cold rent).
There is no binding statutory table. The "Mietminderungstabellen" (rent-reduction tables) in circulation are merely collections of court decisions for orientation. Typical guideline figures from case law:
| Mangel | Reduction rate (guideline) |
|---|---|
| Heating failure | up to 20 % (up to 100 % if uninhabitable) |
| Mould | approx. 5–25 %, large-scale with health risk up to 100 % |
| Water damage (large-scale, not self-caused) | 25–30 % |
| Practical overall range | 5 % – 100 % |
Achtung: Do not reduce too much on your own. An excessive or unjustified Mietminderung creates an arrears — and that can trigger a fristlose Kündigung (termination without notice) under § 543 Abs. 2 Nr. 3 BGB. If you are unsure about the correct amount, pay the full rent "unter Vorbehalt" (subject to reservation) and additionally assert your Zurückbehaltungsrecht.
May I repair it myself and deduct the cost?
This is the riskiest option — and only allowed in two cases (§ 536a Abs. 2 BGB):
- Nr. 1 — Verzug: the landlord is in default with the repair. This requires that you first reported it, set a deadline, and that the deadline passed without action.
- Nr. 2 — Emergency: immediate repair is necessary to preserve or restore the flat (e.g. burst pipe, heating failure in winter). Then you may act even without Verzug.
If neither case applies and you repair on your own initiative, you are usually not reimbursed — not even by indirect routes (BGH, judgment of 16.01.2008 – VIII ZR 222/06). So the rule is: always report and set a deadline first, unless it is a genuine emergency.
Important for the Aufwendungsersatz (reimbursement of expenses): your claim becomes time-barred six months after the tenancy ends (§ 548 Abs. 2 BGB).
How much rent may I withhold as leverage?
On top of the reduction you may withhold part of the (already reduced) rent until the Mangel is fixed (§ 320 BGB). This is leverage, not a final deduction.
- Amount: by case law, as a rule 3 to 5 times the monthly reduction amount, capped by proportionality (§ 320 Abs. 2, § 242 BGB). The total withheld must stand in reasonable relation to the significance of the Mangel (BGH, judgment of 17.06.2015 – VIII ZR 19/14).
- From when: the Zurückbehaltungsrecht only arises for rent that falls due after the Mangelanzeige — because only once the landlord knows can it exert pressure (BGH, judgment of 03.11.2010 – VIII ZR 330/09).
- Afterwards: unlike the reduction amount (which is lost for good), withheld amounts must be paid back once the defect is fixed.
Common mistakes
- Reporting the Mangel too late or not at all. You lose Mietminderung, damages and the right to terminate, and may be liable for consequential damage (§ 536c Abs. 2 BGB).
- Reporting only verbally. Legally valid, but not provable in a dispute. Always use Textform with a date and photos.
- Repairing on your own without prior Verzug. Without a deadline and Verzug (and without an emergency) there is no reimbursement.
- Reducing too much. An excessive Mietminderung can lead to a fristlose Kündigung. When in doubt, pay unter Vorbehalt.
- Reducing from the Kaltmiete (net cold rent). The reference figure is the Bruttomiete (gross/warm rent).
- Trying to announce the reduction. Not necessary — it takes effect automatically. All that is required is the Mangelanzeige.
HausMaus makes this easier
With HausMaus you report a Mangel directly to your landlord (issue report), keep the repair deadlines you set in view in the deadlines tracker, and generate the correct, legally sound Mangelanzeige straight out of the Mietminderung calculator (§ 536 BGB). That way you report every defect in the proper form, document it for evidence and keep your rights. For tenants it is free. Wohnen, geregelt. (Home, handled.)
Frequently asked questions
How do I report a defect to my landlord correctly?
Report the defect unverzüglich (without culpable delay) under § 536c BGB in conjunction with § 121 BGB. No form is legally required, but for proof you should report in writing or in Textform (text form, e.g. email): describe the Mangel precisely, attach photos, and set a reasonable deadline for the repair (around 14 days for ordinary defects). In an acute emergency, report immediately, by phone if needed.
My landlord won't repair — what deadline must I set?
The law names no fixed deadline; it only has to be reasonable. The practical rule of thumb is about 14 days for ordinary defects. For heating or hot-water failure in the cold season only a few days, or immediate action, is reasonable, because it counts as an emergency (§ 536a Abs. 2 Nr. 2 BGB).
Can I do the repair myself and deduct the cost from the rent?
Only in two cases (§ 536a Abs. 2 BGB): if the landlord is in Verzug (default) with the repair (i.e. after you reported it, set a deadline and the deadline passed without action), or if immediate repair is necessary to preserve the flat (a genuine emergency). Anyone who acts on their own without Verzug is usually reimbursed nothing (BGH, VIII ZR 222/06).
Do I have to announce the Mietminderung in advance?
No. With a significant Mangel the rent is reduced automatically by operation of law, from the moment the impairment begins (§ 536 BGB). You do not have to declare the Mietminderung (rent reduction). The only precondition is that you have reported the Mangel (§ 536c BGB).
How much Mietminderung can I claim for mould or heating failure?
There is no binding table, only court guideline figures for the individual case: heating failure up to 20 % (up to 100 % if the flat is uninhabitable), mould roughly 5–25 % depending on extent, and up to 100 % for large-scale infestation that endangers health, large water damage 25–30 %. The reference figure is the Bruttomiete (gross/warm rent).
How much rent may I withhold until the defect is fixed?
On top of the reduction you may withhold part of the rent as leverage (§ 320 BGB), as a rule 3 to 5 times the monthly reduction amount. The Zurückbehaltungsrecht (right of retention) only arises for rent falling due after the Mangelanzeige (BGH, VIII ZR 330/09). Withheld amounts must be paid back once the defect is fixed.
Sources
This guide is based on the statute text and official sources. You can read the cited paragraphs in the original here: