How is a rent reduction calculated?
Rent reduction in Germany is calculated based on the gross warm rent (Bruttowarmmiete) – the base rent plus all utilities and heating costs. This was established by the Federal Court of Justice (BGH) in its landmark ruling of July 20, 2005 (Az. VIII ZR 347/04).
The formula is:
Example: With a gross rent of €900 and mold in the bedroom (reduction rate 15%) over 20 days:
Rent reduction takes effect automatically by law (§ 536 BGB) – you do not need to apply for it. However, you must first notify your landlord of the defect in writing (Mängelanzeige).
Rent reduction table: How much for which defect?
The amount of rent reduction depends on the type and severity of the defect. The following values are based on published court rulings and serve as guidance:
Mold in the apartment
All 14 rulings →Minor
10 %
median of 6 rulings
Small mold spots, single area, e.g. bathroom or window area
Moderate
23 %
median of 4 rulings
Mold in living areas, multiple spots, musty smell
Severe
78 %
median of 4 rulings
Large-scale mold, health risk, multiple rooms affected
Heating failure / no hot water
All 19 rulings →Minor
10 %
median of 6 rulings
Heating works with limitations, single room affected, temperature 16–18 °C
Moderate
25 %
median of 5 rulings
Heating failure in multiple rooms, temperature below 16 °C
Severe
73 %
median of 8 rulings
Total heating failure in winter, apartment uninhabitable
Water damage / burst pipe
All 17 rulings →Minor
8 %
median of 4 rulings
Cosmetic damage, small area affected, discoloration
Moderate
23 %
median of 4 rulings
Significant water damage, room impaired, damp walls
Severe
80 %
median of 9 rulings
Severe flooding, multiple rooms affected, apartment barely habitable
Noise / construction noise
All 21 rulings →Minor
8 %
median of 5 rulings
Occasional disturbance, daytime, e.g. sports field or neighbor
Moderate
20 %
median of 11 rulings
Regular noise disturbance, construction work, affects daily life
Severe
40 %
median of 5 rulings
Extreme constant noise, day and night, apartment barely habitable
Power outage
All 11 rulings →Minor
8 %
median of 7 rulings
Partial outage, one area, limited supply (e.g. hot water only after a delay)
Moderate
20 %
1 ruling
Outage in the whole apartment for one to several days, e.g. no hot water
Severe
100 %
median of 3 rulings
Long-term total outage: no light, no heating, no hot water
Pests / vermin
All 10 rulings →Minor
10 %
median of 3 rulings
Minor infestation, single area, e.g. silverfish in bathroom
Moderate
15 %
median of 4 rulings
Significant infestation, multiple rooms, quality of life severely affected
Severe
100 %
median of 3 rulings
Massive infestation, health risk, apartment uninhabitable
Elevator defective
All 8 rulings →Minor
6 %
median of 4 rulings
Lower floors (up to 3rd floor), short outage
Moderate
10 %
median of 3 rulings
Middle floors (4th–6th floor), longer outage
Severe
20 %
1 ruling
Upper floors (7th floor and above), long-term outage, elderly/mobility-impaired tenants
Median reduction rates of the court rulings in our rent reduction table, per severity level. The figures update with every new ruling; individual cases may differ.
View the complete rent reduction table with all court rulings →
Frequently asked questions about rent reduction
Is rent reduction calculated from gross or net rent?
Rent reduction is always calculated from the gross warm rent – base rent plus all utilities including heating costs. This was decided by the BGH in its 2005 ruling (Az. VIII ZR 347/04).
Do I need to announce the rent reduction?
No, rent reduction takes effect by law. However, you must notify your landlord of the defect (Mängelanzeige). Only from that point on may you reduce the rent. A 14-day deadline for repair is standard.
Can I reduce rent retroactively?
In principle yes, but only from the point when you notified the landlord of the defect. Tip: Pay rent under reservation of reclaiming the amount, then you can demand the difference back later.
How much percent rent reduction for mold?
It depends on the extent. Median of the rulings in our rent reduction table: 10% for small spots in one place, 23% for mold in several places in living rooms, 78% for extensive mold with a health risk. Use the calculator above for an estimate in euros.
Can I reduce rent without a lawyer?
Yes. For out-of-court claims, you do not need a lawyer. What matters is a proper defect notification, the right reduction rate, and correct calculation. Our calculator and letter generator help you with that.
What happens if I reduce too much?
If you withhold too much rent, the landlord could terminate the lease for non-payment. That is why it is important to follow court rulings and calculate the reduction correctly. When in doubt, pay under reservation and reclaim the amount later.
Rent reduction per day or per month?
Rent reduction is calculated on a daily basis. If the defect exists for only part of the month, the monthly rent is divided by 30 and multiplied by the number of affected days.
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