How to calculate a rent reduction correctly
The formula is: reduction amount = gross warm rent × reduction rate × (days with the defect ÷ days in the month). Example: your gross warm rent is €900, the heating fails on 10 of 31 days in January, and the reduction rate is 20%. Calculation: €900 × 0.20 × 10 ÷ 31 = €58.06. You pay €841.94 for January instead of €900. You take the reduction rate from a rent reduction table. If the defect affects only one room, you also weight the figure by that room's share of the living value from the Hamburg table, which you will find further down.
In short
- Under § 536 BGB (German Civil Code), the rent is reduced automatically when there is a defect. You only have to calculate the amount correctly.
- The basis is the gross warm rent (Bruttowarmmiete), not the net cold rent (Federal Court of Justice, judgment of 6 April 2005, VIII ZR 192/04).
- The rent is reduced only for the days on which the defect existed. If the defect is in a single room, that room's share of the living value counts as well.
- If the landlord demands additional service charges, reduce that demand at the same rate too.
Which defects give you the right to a rent reduction?
If one or more defects lower the quality of your home, § 536 BGB gives you the right to reduce the rent in proportion. Defects come in many forms.
For example:
- a heating failure (especially in winter)
- construction noise in the neighbourhood
- mould on the walls of the flat
- water damage, or
- loss of hot water
Every case on this incomplete list gives you the right to reduce the rent.
The amount should be neither too high nor too low. Too low, and you give money away. Too high, and you risk legal trouble later.
That leaves two options: read up on every detail of the subject yourself, or hand your case to legal experts.
Information you need for the calculation
To work out the correct reduction amount, you need the reduction rate, the gross warm rent, the amount of the service charges and the share of the living value of the rooms affected by the defect.
The last figure matters because
- not every room has the same living value (compare the living room with the cellar), and
- not every room is affected by the defect in the same way (mould in the cellar and bathroom, but not in the living room)
The courts have already set these shares (Regional Court of Hamburg, 24 May 1983, 16 S 332/82). Broken down by room, they form the so-called Hamburg table:
- Living room: 28 per cent.
- Study: 20 per cent.
- Bedroom: 12 per cent.
- Kitchen: 10 per cent.
- Bathroom: 10 per cent.
- Storage room: 7 per cent.
- Guest WC: 3 per cent.
- Balcony: 10 per cent.
Finally, note exactly how long the defect lasted. Time is a key factor in the calculation.
The reduction rate
The reduction rate expresses, as a percentage, how much the defect impairs the use of your flat. It depends on how serious the defect is and how long it lasts.
Many factors feed into the reduction rate, for example
- the size and location of the flat
- the technical standard
You do not need to work out the reduction rate yourself. The rent reduction tables, published afresh each year, list the values that fit your case.
How the reduction amount is calculated
First you need the correct assessment basis. If the defect existed for only 10 days, the rent cannot be reduced for the whole month.
Example calculation:
Your gross warm rent is €580 and the defect existed for 9 consecutive days from 25 February to 5 March.
So we are looking for the correct time basis. Because the defect spans two months and lasted less than a full month, you proceed as follows:
€580 × 4 days (defect in February) ÷ 28 days = €82.86; for March, likewise
€580 × 5 days (defect in March) ÷ 31 days = €93.55
Adding the two gives the assessment basis: €176.41.
That is the basis. What we want to know is the amount by which the rent may actually be reduced. The rent reduction table mentioned above answers that.
Suppose the table gives a reduction rate of 25% for the defect in our example. The reduction amount is then:
€176.41 × 25% = €44.10
Deduct this amount from the gross warm rent: €580 − €44.10 = €535.90
Important: factor in the service charge prepayments
If the landlord demands additional service charges (because the actual service charges exceed the prepayments), you reduce that amount proportionally too. An example:
Gross warm rent €580
Landlord's additional service charge demand €400
Reduction rate 25%
For simplicity, assume the defect existed for 2 full months. Without a rent reduction, the annual rent would be:
12 months × €580 (gross warm) + €400 (additional service charges) = €7,360
With the rent reduction, you first reduce the gross warm rent for 2 months, then do the same with the additional amount demanded.
- Step 1: €580 − 25% (reduction rate) = €435 (reduced warm rent per month)
- Step 2: 10 months × €400 ÷ 12 + 2 months × €25 (reduced service charge demand per month) = €383.33 (reduced service charge demand per year)
The €25 is the monthly service charge demand reduced by the 25% reduction rate (€400 ÷ 12 − 25%).
Putting all the components into the formula gives a reduced annual rent of:
10 months × €580 + 2 months × €435 + €383.33 = €7,053.33
The annual reduction amount including service charges is: €306.67
Without the service charges, it is only: €290
2 months × €580 (gross warm) − 25% (reduction rate). So you give money away. Depending on the reduction rate, the amount lost can be much higher.
The service charge statement is therefore an essential part of the calculation. Without knowing the service charges actually incurred, you cannot calculate the reduction amount correctly, or it will come out too low.
Experts help you calculate the rent reduction
As you can see, calculating the correct rent reduction is fairly complex. That would not matter much if there were no legal consequences at stake. If the reduction is too low, that is annoying at best. If it is too high, the landlord can in theory claim damages and even terminate the tenancy.
So back to the question from the start of this article: is it wiser to read up on every detail yourself, or to leave the calculation to specialists? The choice is yours.
CONNY is on your side
- Fill in the online questionnaire and get your result straight away.
- We review your case and, once you instruct us, enforce your rent reduction claim.
- You receive your payout. CONNY covers all legal and court costs.
Thousands of tenants have already reduced their rent with CONNY.
With CONNY you have a trusted partner who calculates your rent reduction correctly and enforces it. You pay only if we succeed.