Rent reduction for defects: how much, from when – and without hurting yourself

A black patch on the bedroom wall, a heater that stays cold in January, or a building site that starts up at seven in the morning: housing defects are annoying – and they cost you living quality you're paying full rent for. German tenancy law hands you a powerful tool for this, the rent reduction. The misunderstanding that most often gets expensive, though, isn't "May I?" or "How much?" – it's the assumption that reducing is risk-free.

It isn't. Whoever reduces too much or too early ends up paying too little rent, unknowingly builds up arrears and, in the worst case, can lose the flat. That's why this article flips the usual order: first the clean sequence and the risk, then the number. If you're in a hurry, run your case straight through the calculator – it shows you not just a range, but also from when your withheld amount becomes dangerous.

When are you actually allowed to reduce?#

The reduction is neither an act of grace by the landlord nor an application you file. It takes effect automatically as soon as the flat has a material defect – the statute puts it so that for the duration of the defect the tenant owes only "an appropriately reduced rent" Quelle. So you owe less of your own accord; the reduction arises by operation of law, not through your declaration.

A defect here is any deviation from the contractually owed condition that removes or diminishes the flat's fitness for the agreed use. Whether the landlord is to blame is expressly irrelevant – fault does not matter. Even water damage caused by a neighbour or noise from someone else's building site can justify a reduction, although the landlord can do nothing about it.

But you must know two limits. First: trivialities don't count. A merely insignificant reduction in fitness is disregarded (§ 536 (1) sentence 3 BGB) – a dripping tap or a hairline crack in the plaster isn't enough. It takes a material defect. Second: whoever already knew the defect loses the right. If you knew of the defect at the time the contract was concluded, no reduction is due; in cases of grossly negligent ignorance only if the landlord fraudulently concealed it Quelle. And if you accept a visibly defective flat, you must reserve the reduction on handover, otherwise it is lost.

One reassuring point to close this section: for residential leases the right to reduce cannot be contracted away. A clause in the tenancy agreement that excludes or restricts it to the tenant's disadvantage is void (§ 536 (4) BGB). Anything the contract says to the contrary simply doesn't apply.

The right order: report first, then reduce#

This is where the mistake that makes most guides imprecise hides – and it costs money in practice. The reduction does take effect by operation of law, but you can only enforce it if you fulfil a single duty: the defect notice. You must notify the landlord of the defect without undue delay Quelle. That is the only formal act actively required of you.

What happens if you fail to do it? If you don't report the defect (in time), you lose the right to reduce for the period of the omitted notice – and are additionally liable to the landlord for damages if, because of your silence, he could not provide a remedy in time (§ 536c (2) BGB). Put differently: whoever pays the full rent in silence for three months and then wants to reduce retroactively usually can't reclaim that time.

This lets you answer the frequently asked question "From when does the reduction take effect?" precisely. Legally it arises with the defect, not only with the notice. But a late notice deprives you of the reduction for the period before it. In practice: whoever reports at once reduces from the start of the defect; whoever waits loses the time up to the notice. The popular shorthand "reduction only from the notice" is therefore mostly right – but legally imprecise. So report the defect at once and verifiably: in writing, with a date, a description and – for mould or water damage – photos.

A notice is not the same as setting a deadline#

A second, equally common confusion: for the pure reduction you do not need to set the landlord a deadline to remedy the defect. The notice suffices. Setting a deadline or issuing a warning only becomes relevant for other rights – for instance if you want to remedy the defect yourself and be reimbursed (§ 536a BGB), or terminate extraordinarily because of the defect (§ 543 (3) BGB). Confuse the two and you either wait unnecessarily long before reducing or wrongly consider yourself not entitled.

And a further relief: you don't have to announce or justify the reduction itself. You report the defect – the reduction follows on its own from the statute. Still, it's wise to tell the landlord that and by how much you are temporarily cutting the rent, so he isn't surprised and you have documented the exchange.

Document the defect from the outset#

Because the burden of proof for the defect and its severity lies with you, in a dispute the documentation often decides more than the legal position. Record the condition as concretely as possible: dated photos, for mould or damp ideally with a visible scale, for cold or noise a defect log with times and measured values (indoor temperature, decibel estimate, duration). Note when the defect began, when you reported it and how the landlord reacted. Witnesses – flatmates or neighbours, say – you should record by name. These records cost you little time, but they are what makes your reduction enforceable at all when it comes to the crunch and a court has to estimate the rate under § 287 ZPO.

What is the reduction calculated from? From the gross rent#

Before it's about percentages, the calculation basis has to be right – and this is exactly where many online tables and calculators get it wrong. You reduce not the net cold rent but the gross rent: the total rent including all operating and service charges. This is settled by the highest court Quelle. Whether the service charges are owed as a flat rate or as an advance payment makes no difference.

The difference isn't academic. At €700 cold rent plus €200 service charges, a 20 % reduction is not €140 but €180 per month – the rate applies to the full €900. Whoever uses only the cold rent reduces too little and gives money away. The calculator above takes this off your hands: enter the warm rent and it applies the rate to the correct amount.

How much? Ranges from case law, not fixed rates#

Now the question everything revolves around – and the most common source of error. There is no statutory reduction table. The statute names not a single percentage. Instead, in a dispute the court estimates the amount "on an assessment of all circumstances at its free conviction" Quelle. The "reduction tables" doing the rounds are nothing but collections of individual judgments by local, regional and higher regional courts. They show how courts decided in comparable cases – not how much you're owed.

That's why the calculator above deliberately outputs a range and never a single value. A few reference points from documented decisions, to give you a feel for the order of magnitude:

Two things about this table matter more than the numbers themselves. First: the values spread enormously, because it depends on severity, duration, the affected living area and the season – a heating failure weighs more in January than in May. Second: for some defects such as vermin, high figures circulate (up to 80 % for severe rat infestation) but without a documented individual case reference; such numbers are collective guide values, not judgments. The calculator flags this accordingly, so you don't rely on false precision.

A short worked example makes the scale tangible. Suppose your gross rent is €900 and visible mould has been forming on the outside wall of your bedroom for four weeks. The documented range runs from around 10 to 50 %; for a moderate, clearly visible infestation in a living space many judgments sit around 20 %. That would be €180 per month. If the defect persists for three months, the withheld amount adds up to €540 – still well below one month's rent, and thus in the uncritical zone. But set 40 % and let the defect drag on for five months, and it's already €1,800 – two full months' rent, and this is exactly where the dangerous zone begins. The calculator does the same sum for you, including the warning as soon as the withheld amount tips over.

Where several defects occur at once, the rates are, by the way, not simply added. The court forms an overall assessment of the impaired fitness for use – two defects of 30 % each do not make 60 %. When in doubt, calculate more conservatively and refer to the overall condition of the flat, not to a sum of individual items.

The real risk: reducing too much can cost you the flat#

This is the part most rate calculators keep quiet about – and the most important of the whole article. You always reduce at your own risk. If a court later sets a lower rate than you did, the difference was owed the entire time. Your "reduction" retroactively becomes rent arrears. And rent arrears are the classic ground for termination without notice.

The thresholds for this are set out in the statute and are alarmingly low. The landlord may terminate without notice if you are in default on two consecutive dates with a not insignificant part of the rent – or, over a longer period, with an amount reaching two months' rent Quelle. For residential leases, "not insignificant" is made concrete: the arrears already are so once they exceed one month's rent Quelle. So whoever cuts too much over a few months crosses this line faster than they think – which is precisely what the "cumulative withheld amount" in the tool computes.

There is a lifeline, but don't count on it: the termination without notice becomes ineffective if the arrears are settled in full at the latest two months after service of the eviction claim (grace-period payment, § 569 (3) no. 2 BGB). The snag: it works only once every two years, and under the case law it heals the termination without notice but often not an ordinary termination declared at the same time. A safety net with holes – no reason to take the risk.

The safe route: paying under reservation#

If the risk is this real – why cut at all? Because there's a way to keep the benefit of the reduction and almost entirely avoid the termination risk: pay the full rent under reservation.

The mechanics are simple. You keep transferring the full rent but declare to the landlord verifiably and in writing that you are paying part of it only "under reservation of reclaim" because of the defect. In practice: a corresponding note in the transfer reference, plus a short written communication, and keep the receipts. Whoever pays the full rent cannot fall into payment default – and without default there is no ground for termination under § 543 (2) no. 3 BGB.

You thereby swap a dangerous risk for a milder one: instead of termination without notice you now bear only a litigation and evidence risk when you later (if need be, in court) reclaim the overpaid part. Two limits you should know: the reservation must be express and documented – an unreserved payment in knowledge of the defect can be read as a waiver. And the route isn't meant to last forever: pay unreservedly for many months despite the defect and the landlord may assume your agreement.

Precisely this option is what the calculator above places on an equal footing with the rate – not as a footnote. As soon as your withheld amount slips into the critical zone, it actively recommends the reservation.

The most common mistakes – and how to avoid them#

1. 1

   Cut first, report later (or never)

   The notice is the entry ticket. Without it you lose the reduction for the time up to the notice (§ 536c BGB). Always report in writing and verifiably first, then reduce.

2. 2

   Calculating from the cold rent instead of the gross rent

   The rate applies to the warm rent incl. service charges (BGH VIII ZR 223/10). Whoever takes only the cold rent reduces too little.

3. 3

   Taking a table figure for an entitlement

   The percentages are individual judgments, not statutory rates. Take the range as orientation and stay towards the lower-to-middle end if the case isn't clear-cut.

4. 4

   Reducing too much and overlooking the arrears

   The withheld amount adds up. Once it exceeds one or two months' rent, termination without notice looms (§ 543, § 569 BGB). When in doubt, pay under reservation.

5. 5

   Acting orally instead of in writing

   Notice, reduction amount and reservation belong in text form, sent verifiably – otherwise in a dispute it's your word against theirs.

What the calculator can do – and what it can't#

So you read the result correctly: the calculator above computes two things exactly – the reduction amount from the rate and the gross rent, and the cumulative withheld amount over the duration. Both are pure arithmetic. The rate itself, by contrast, it cannot take off your hands: it depends on the severity, duration and provability of your specific defect and is estimated by the court in a dispute. That's why it outputs a range and not a single figure.

What the calculator deliberately does not judge is whether your defect is "material" enough, whether your evidence holds or whether special features apply in the individual case. That's a legal assessment. It tells you what order of magnitude you're in and when it gets risky – the final assessment of a contested case belongs to the tenants' association or to a lawyer specialising in tenancy law.

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