Mietminderung: How Rent Reduction for a Defect Actually Works Under § 536 BGB

Mietminderung is the reduction of rent that follows automatically when a rented dwelling has a defect serious enough to more than insignificantly impair its use. The tenant does not apply for it, and no court has to grant it before it takes effect. It happens by operation of law from the moment a qualifying defect exists.

That automatic quality is also what makes Mietminderung risky to get wrong. This page explains how the reduction actually arises, why the percentage tables circulating online are not a tariff a tenant is simply entitled to apply, and the real consequences of withholding too much rent.

Information last verified on 20 July 2026. This page provides general legal information and does not constitute legal advice in an individual case.

Why this happens automatically, and why that is not simple

§ 536 Abs. 1 BGB provides that where a defect eliminates the dwelling's fitness for the contractually intended use, the tenant is freed from paying rent for that period, and where the defect merely reduces that fitness, the tenant owes only an appropriately reduced rent. An insignificant impairment is disregarded entirely and does not trigger any reduction.

The automatic nature of this rule is exactly what makes it harder in practice than it sounds. Because no landlord, court or agency confirms the percentage in advance, the tenant is effectively making a legal judgment call every time rent is due for the affected period, and that judgment can turn out to be wrong. Getting it wrong does not just mean losing an argument later. It can mean the tenant has actually been underpaying rent the whole time, with consequences described below.

The percentage tables are case law, not a tariff

Searching for Mietminderung online turns up tables listing specific defects next to specific percentages: a certain figure for mould in a bedroom, another for a broken heating system in winter, another for construction noise from a neighbouring site. These tables are real in the sense that each row usually traces back to an actual court decision. They are not real in the sense of being a binding schedule the tenant can simply apply.

Each of those percentages was set by a court weighing the specific severity of a specific defect, in a specific dwelling, against the specific rent and circumstances of that case. A defect described in similar words in two different disputes, a leaking roof, say, can justify very different reductions depending on how much of the dwelling was affected, how long it lasted, and how it was proven. Treating a table entry as an entitlement, rather than as one illustration of how one court reasoned about one set of facts, is the single most common mistake tenants make with Mietminderung, and it is the mistake this page is written to head off.

As a rough illustration only, and not as a rule to apply directly to a specific dwelling, published decisions have found reductions in roughly this kind of range for these categories of defect. These figures are examples of outcomes courts have reached, not a menu.

None of these ranges is a promise about what any particular case would receive. A tenant relying on a table entry to calculate their own reduction is substituting someone else's court's reasoning, on someone else's facts, for their own situation, and that substitution is exactly where the arrears risk described below comes from.

The real risk: reducing by too much

Because the reduction happens automatically rather than by court order, a tenant who withholds a portion of rent based on their own estimate is taking a position that may or may not hold up. If a court later finds the actual defect justified a smaller reduction than the tenant applied, the difference between what was paid and what was actually owed is unpaid rent, in arrears, from the date it fell due.

That arrears exposure is not abstract. § 543 Abs. 2 Satz 1 Nr. 3 BGB lets a landlord terminate a tenancy without notice where the tenant is in arrears on two consecutive due dates for an amount that is not insignificant, or where arrears accumulate over more than two due dates to reach the equivalent of two months' rent. A tenant who reduces rent by, say, 40 percent believing a defect justifies it, when a court later finds only 15 percent was justified, can accumulate exactly this kind of arrears within a few months without ever intending to fall behind.

This is why this page frames Mietminderung as a rule to understand carefully rather than a self-help remedy to apply aggressively. A cautious, well-documented reduction, backed by photographs, dates and the landlord's own acknowledgment of the defect where possible, is far safer than an aggressive one based on an online percentage table.

Paying under reservation as the safer route

Where the correct percentage is genuinely uncertain, paying the rent in full while reserving the right to reclaim the disputed portion later, paying unter Vorbehalt, avoids the arrears risk entirely while the dispute is worked out. The tenant states clearly, in writing, that the payment is made without prejudice to a claim that part of it was not actually owed because of the defect, then pursues the reduced amount separately as a repayment claim under the general unjust enrichment rules in § 812 BGB once the extent of the defect and the appropriate percentage are clearer.

This route trades a faster cash benefit for materially lower risk. The tenant is not out of pocket forever, since the reserved amount can still be reclaimed, but the tenant is never technically in arrears while that question is being resolved, which removes the termination risk entirely for as long as the reservation is properly made and maintained. Any such reclaim is subject to the general limitation period in § 195 BGB, ordinarily three years, so a tenant should not delay indefinitely before pursuing it.

The notification duty

§ 536c BGB requires the tenant to notify the landlord immediately once a defect appears. This is not a formality. A tenant who fails to notify can lose the right to reduce rent for the period before the landlord actually found out about the defect some other way, lose any damages claim under § 536a BGB for that period, and become liable to the landlord for any additional damage that resulted from the delay in fixing it.

Notification should be specific: what the defect is, when it was noticed, and ideally photographic evidence and a request that the landlord remedy it within a reasonable time. A vague or undocumented complaint is harder to rely on later if the landlord disputes that notice was ever given.

Knowledge at signing forecloses the claim

§ 536b BGB removes the right to reduce rent, or to claim damages, for a defect the tenant already knew about when the lease was signed. The same applies where the tenant later accepted the dwelling with knowledge of the defect, for example at handover, without reserving their rights at that point. A tenant who moves in aware that a particular fixture does not work, and says nothing, generally cannot rely on that same defect for a Mietminderung claim later.

The one exception is where the landlord fraudulently concealed the defect. Ordinary negligence in failing to notice a defect does not preserve the tenant's rights on its own if the underlying awareness standard in § 536b BGB is otherwise met, but a landlord who actively hid a known problem is treated differently.

The reduction applies to the gross rent

Where a lease separates a base rent from advance payments for operating costs, the Mietminderung percentage is applied to the combined, gross figure, not to the base rent alone. A tenant paying EUR 800 in base rent plus EUR 200 in operating cost advances, for a gross rent of EUR 1,000, who is entitled to a 20 percent reduction, reduces the total EUR 1,000 by 20 percent, not the EUR 800 base rent by 20 percent. Getting this basis wrong understates what the tenant is actually entitled to withhold or reclaim.

Worked example, framed carefully

A tenant's only working heating system fails in December and is not repaired for three weeks despite prompt notification to the landlord in writing, with photographs of the thermostat and a request for urgent repair. Published decisions involving a complete loss of heating in winter have found reductions toward the higher end of the range, sometimes a majority of the rent, reflecting how central heating is to a dwelling's basic habitability in cold weather.

Rather than picking a specific percentage from an online table and withholding that amount outright, the more defensible approach is to pay the full gross rent for that period under reservation, documenting the defect, the notification date and the repair date, and then pursue the specific reduced amount as a separate reclaim once the facts are clear and, if necessary, with legal advice on what percentage a court would likely find justified on these specific facts. This avoids any arrears exposure while preserving the full value of the claim.

For related tenancy questions, see the security deposit and ending a tenancy. General background on German tenancy law is at German law explained.