A heating replacement in a rented flat raises two questions that tenants ask most often: who decides about it, and who ends up paying? The answer lies in the interplay of ownership, heating law and tenancy law. This guide separates the decision, the costs and the possible rent increase, so you can classify each step correctly. German terms appear in brackets where they matter.
Short answer: The landlord, as owner, usually initiates the heating replacement. Under section 559 subsection 1 of the German Civil Code (BGB, Bürgerliches Gesetzbuch), the landlord may pass on 8 percent of the costs per year through the rent. Under section 559 subsection 3a sentence 3 BGB, the rent increase when a heating system is installed is capped at 0.50 euro per square metre within six years. Last updated: November 2026.
The most important points in brief
- The decision on the heating replacement lies with the landlord as the owner of the building.
- Under section 559 subsection 1 BGB, the landlord may raise the annual rent by 8 percent of the costs incurred for the flat.
- For an eligible measure with subsidy actually used, section 559e BGB sets a different rate: 10 percent of the costs minus the third-party funds.
- According to the wording of section 559 subsection 3a BGB, heating systems also carry a cap of 0.50 euro per square metre of living space within six years.
- The general cap of 3 euro per square metre within six years continues to apply alongside it.
- If you want to claim hardship, notify the reason in good time after the announcement.
Who decides about the heating replacement?
The owner and landlord decide on the heating system of the building. As a tenant you usually have no direct influence on the choice of system, but you do have influence on the costs that later feed into the rent. This is where tenancy law and heating law meet.
Heating law determines which systems may be used and which duties apply. According to the specialist portal, the rules changed in 2026 because the Building Energy Act (Gebäudeenergiegesetz) was reissued under the name Building Modernisation Act (Gebäudemodernisierungsgesetz). You should check the exact duties against the official statutory text, because the portal does not reproduce the full wording. The guide on the Building Modernisation Act for tenants covers the heating rules in more depth (in German).
Who pays for the heating replacement?
At first the landlord bears the costs of the measure. The modernisation levy (Modernisierungsumlage) allows the landlord to recover part of them through the rent. The share for ordinary maintenance (Instandhaltungsanteil) has to be deducted. According to the specialist portal, the landlord must determine this share or estimate it.
For you, this means that the costs do not arrive as a single payment. They show up in the rent over several years. The amount depends on how expensive the measure was, whether a subsidy was paid and how the caps apply. A close look at the announcement is therefore worthwhile.
How high may the rent increase be?
The table below shows the limits named in the statutory text (retrieved on 2 November 2026). The amounts refer to each square metre of living space and do not apply as a flat sum to every flat.
| Case | Rule | Source |
|---|---|---|
| Levy without a subsidy | 8 percent of the costs per year | Section 559 subsection 1 BGB |
| Levy with a subsidy | 10 percent of the costs minus the third-party funds used, cap 0.50 euro per m² within six years | Section 559e BGB |
| Cap for heating systems | at most 0.50 euro per m² within six years | Section 559 subsection 3a sentence 3 BGB |
| General cap | at most 3 euro per m² within six years, or 2 euro where the rent is below 7 euro per m² | Section 559 subsection 3a sentences 1 and 2 BGB |
The table only summarises the rules named. Whether they apply in your case depends on the announcement and the actual costs.
What does a worked example look like?
Assumption: The modernisation costs are 20,000 euro, the subsidy 6,000 euro and the living space 80 square metres. After deducting the maintenance share, 17,000 euro of costs that can be passed on remain (assumed; the size of the deduction depends on the case). After deducting the subsidy, 11,000 euro remain, and 10 percent of that per year is 1,100 euro, or about 91.67 euro per month. However, the cap for heating systems limits the increase to 0.50 euro per square metre, which is 40 euro per month at 80 square metres.
The example shows that the arithmetical levy and the actual increase can diverge. The decisive factor is the cap that the landlord has to respect. The calculation is a model with assumed values, not a statement about your flat.
What applies if the landlord receives a subsidy?
If the measure is subsidised, the calculation shifts. Section 559e BGB names the rate of 10 percent of the costs minus the third-party funds for this case. The cap of 0.50 euro per square metre within six years also applies here. Whether and to what extent a subsidy was promised is shown in the funding notice, which you can ask the landlord for.
Tenants should check whether the landlord has taken the subsidy into account in the calculation. A calculation without the deduction of the subsidy merits a precise enquiry.
When can you resist the levy?
Hardship can lead to the levy being dropped. According to the specialist portal, the tenant must notify the reason for hardship in good time after the announcement. Anyone who states the reason later may lose an opportunity. Whether a hardship exists is always assessed on the individual case.
Read the announcement carefully. Pay attention to the costs, the information on subsidies, the maintenance share and the size of the announced increase. In case of doubt, a tenancy law advice service, for example a tenants’ association, can help.
Frequently asked questions
May the landlord simply replace the heating?
The decision on the measure lies with the landlord as the owner. Limits under tenancy law follow from the rules on modernisation, in particular from the announcement and the caps. Whether a replacement is permissible in your case therefore depends on the circumstances.
Do I have to pay for the new heating?
You do not pay the costs as a single sum, but through a possible rent increase. The rent may only rise within the framework that the modernisation rules and the caps allow. How much this amounts to in an individual case is shown in the landlord’s calculation. The announcement should state the costs and the basis of the calculation so that you can check the levy.
What happens to the maintenance share?
The maintenance share is the part of the costs that, according to the specialist portal, may not be passed on through the modernisation levy. The landlord has to determine it or estimate it. You can ask for clarification of this point in the announcement.
Which heating costs arise afterwards?
The rent increase concerns the basic rent. The landlord settles the ongoing heating costs separately through the heating cost statement. The guide on checking the heating cost statement explains how to review it (in German).
How to proceed now
- Read the announcement of the heating replacement in full and note the costs, the subsidy and the announced increase.
- Check whether the maintenance share and the subsidy have been deducted in a traceable way.
- Compare the announced increase with the cap of 0.50 euro per square metre for heating systems.
- Notify a possible reason for hardship in good time after the announcement, if it applies.
- Seek advice from a tenants’ association or a tenancy law service if anything is unclear.
Related guides
- Climate, energy and costs 2027: The overview for tenants and students
- Building Modernisation Act: What changes for tenants when heating
- Checking the heating cost statement: Deadlines, distribution and typical errors
- Reducing heating costs: What tenants can do without renovation
Sources: Section 559 BGB, rent increase after modernisation measures, section 559e BGB, rent increase after installing a heating system (both in German, gesetze-im-internet.de, retrieved on 2 November 2026) and Specialist article Miet-Check: Heating replacement as a landlord, status October 2026, secondary source for maintenance share and hardship (in German).
Last updated: November 2026. This guide is general information, not individual advice.
