Note: This article is for general information only and does not constitute legal advice. The content is based on publicly available case law and statutory texts. For a binding assessment of your individual situation, please contact a lawyer or tenant association (Mieterverein).
Heating costs are the largest individual item in the Nebenkostenabrechnung — on average they account for more than 50% of total operating costs. The Heizkostenverordnung (HeizkV) is intended to protect tenants from non-transparent bills. Even so, around two thirds of all heating cost bills contain errors. In this article, you will learn which rules apply, what you should check, and which options you have.
The 50-70% Rule: Consumption Instead of Area
The core principle of the Heizkostenverordnung (§ 7 HeizkV): heating costs must largely be billed according to actual consumption. The landlord must divide the total costs into two parts:
- Consumption share (50-70%): calculated based on the individually recorded consumption values for your apartment — those who heat less pay less.
- Basic cost share (30-50%): distributed by living space (m²). This share covers provision costs and heat losses in the building.
The usual allocation key is 60/40 (60% consumption, 40% area).
When a 70% consumption share is mandatory: In buildings that do not meet the 1994 Wärmeschutzverordnung, are heated with oil or gas, and mostly have insulated pipes, at least 70% must be billed by consumption (§ 7 para. 1 sentence 2 HeizkV). This affects a large share of older buildings.
Hot-Water Costs: Separation Is Mandatory
If a central heating system also prepares hot water (a so-called combined system), hot-water costs must be separated from heating costs (§ 9 HeizkV). This can be done as follows:
- Best method — heat meter: a central meter directly measures the energy used for hot-water preparation in kWh. Since the end of 2013, this method has been required where technically feasible.
- Substitute formula (§ 9 para. 2): if no heat meter can be installed, the hot-water heat demand is calculated as: Q = 2.5 × hot-water volume (m³) × (hot-water temperature − 10 °C).
- 18% flat rate: as a last resort, 18% of the total costs are applied as the hot-water share. If the stated hot-water share is above 30%, this is a warning sign.
Review tip: Is the 18% flat rate used even though a heat meter is installed? That would be a breach of § 9 HeizkV.
The 15% Reduction Right (§ 12 HeizkV)
Your strongest tool as a tenant: if the landlord bills heating costs not based on consumption even though they are required to do so, you can generally reduce your total cost share for heating and hot water by 15%.
Triggers for the reduction right:
- No recording devices (heating cost allocators/heat meters) installed
- Bill entirely by area instead of consumption
- No heat meter for hot-water separation
- No interim reading when tenants change (although technically possible)
- Allocation key outside the 50-70% corridor
Additional reduction rights since 2021:
- 3% if remote-readable devices are missing (retrofit obligation until December 31, 2026)
- 3% if monthly consumption information (UVI) is missing
In extreme cases, the HeizkV provides for a reduction of up to 21% (15% + 3% + 3%). The reduction right must be actively asserted — it does not apply automatically.
Calculation example: Your heating cost share according to the bill is €1,200. The landlord billed entirely by area (no consumption share). Reduction: €1,200 × 15% = €180. You pay only €1,020.
CO₂ Costs: Landlords Must Share the Cost
Since 2023, the CO₂-Kostenaufteilungsgesetz (CO2KostAufG) has applied. The CO₂ price on fossil fuels (gas, oil) is split between tenant and landlord — according to a 10-level model based on the building's energy condition:
- Well insulated (below 12 kg CO₂/m²/year): tenant pays 100%, landlord 0% — because the landlord has already invested.
- Average (27-32 kg CO₂/m²/year): 60% tenant, 40% landlord.
- Poorly insulated (above 52 kg CO₂/m²/year): tenant pays only 5%, landlord 95% — the renovation pressure lies with the owner.
CO₂ price 2025: €55/tonne. 2026: price corridor of €55-65/tonne (start of auctioning).
The landlord must show the CO₂ costs in the heating cost bill separately and state the level assignment. If this information is missing, you have an additional 3% reduction right.
Consumption Recording and Remote Reading
The landlord is required to equip your apartment with devices for recording consumption — typically heating cost allocators on radiators and hot-water meters.
Important deadlines:
- By December 31, 2026: all non-remote-readable devices must be retrofitted or replaced with remote-readable devices. In case of breach: 3% reduction right.
- By December 31, 2031: all remote-readable devices must be compatible across manufacturers (interoperability).
- Monthly consumption information (UVI): where remote-readable devices are present, the landlord must provide your energy consumption monthly and free of charge — including a comparison with the previous year. If this information is missing: 3% reduction right.
Defective devices (§ 9a HeizkV): If a device has failed or cannot be read, the landlord may estimate consumption — for example based on the previous year's consumption. However, at most 25% of the building area may be estimated. Above that, consumption-based billing is no longer possible.
The Most Common Errors in Heating Cost Bills
Analyses of millions of bills show: around two thirds contain defects. The most common errors:
- Allocation key missing or wrong: the selected key (e.g. 60/40) is missing from the bill or lies outside the permitted 50-70% corridor.
- Entirely area-based billing: the landlord ignores the duty to bill by consumption.
- Vacancy costs allocated to tenants: heating costs for vacant apartments are distributed among the remaining tenants.
- Repair costs hidden: repairs and new purchases (e.g. a new burner) are not allocable — but sometimes appear under "maintenance" or "operation".
- Missing hot-water separation: in combined systems, the hot-water share is not calculated separately.
- Excessive metering-service costs: costs for Techem, ista, or Brunata that amount to more than 15% of total heating costs.
- CO₂ costs not shown: the landlord's share of CO₂ costs is missing from the bill.
More about general billing errors is available in our article The 5 most common errors in Nebenkostenabrechnungen.
New Since 2024: Heat Pumps in the HeizkV
Until October 2024, central heat pumps were exempt from consumption-based billing (the so-called "heat pump privilege"). This privilege has been abolished.
Since October 1, 2025, buildings with a central heat pump must also be equipped with recording devices and bill by consumption. The transition period (until September 2025) for installing devices has expired.
For you as a tenant, this means: if you live in a building with a heat pump and billing is still only by area, the 15% reduction right applies from October 2025.
Heating Cost Benchmarks: Are You Paying Too Much?
The Heizspiegel 2025 (data: billing year 2024) provides comparison values for a 70 m² apartment in an apartment building:
- Natural gas: approx. €1,030/year (€14.70/m²/a)
- Heating oil: approx. €1,030/year (€14.70/m²/a)
- District heating: approx. €1,225/year (€17.50/m²/a)
- Heat pump: approx. €680/year (€9.70/m²/a)
If your costs are significantly above these values, this may be due to poor insulation — or to billing errors. At heizspiegel.de, you can enter your own values and compare them.
A comprehensive guide to checking your entire bill is available in Utility costs too high? How to check your bill.
How to Proceed: Your Rights Step by Step
- Check the bill: is the allocation key correct? Are only allocable costs included? Is the CO₂ share shown?
- Compare: is your amount above the Heizspiegel average? If yes, a closer review is worthwhile.
- Request receipt inspection (§ 259 BGB): you have the right to inspect all receipts: fuel invoices, metering-service provider invoices, maintenance invoices, consumption data for all apartments.
- Object: in writing, within 12 months after receipt of the bill. Name the specific errors. Tips and a template are available in our objection guide.
- Assert the reduction right: in case of breaches of the HeizkV (no consumption share, missing remote reading, missing UVI), request the relevant reduction.
Further Reading
Have Heating Costs Checked Automatically
Are you unsure whether your heating cost bill is correct? NeKo Check reviews your entire Nebenkostenabrechnung automatically — including heating costs, allocation key, hot-water separation, and CO₂ costs. If errors are found, you receive an understandable report with a finished objection letter.
Frequently Asked Questions
What does the Heizkostenverordnung regulate?
The Heizkostenverordnung (HeizkV) requires that heating and hot-water costs in buildings with central heating be billed mainly according to actual consumption — not only by living space. At least 50%, and at most 70%, of the costs must be distributed by consumption.
What is the 15% reduction right?
If the landlord does not bill heating costs by consumption even though required, § 12 HeizkV provides for a 15% reduction right. Since 2021, up to 3% can be added for missing remote reading and 3% for missing monthly consumption information — up to a maximum of 21%.
How are CO₂ costs split between tenant and landlord?
Since 2023, the CO₂-Kostenaufteilungsgesetz (CO2KostAufG) applies a 10-level model. The worse the building's energy balance, the more the landlord pays — from 0% (below 12 kg CO₂/m²/a) to 95% (above 52 kg CO₂/m²/a). The CO₂ price is €55/tonne in 2025.
May my landlord bill heating costs entirely by area?
Generally no. The HeizkV requires consumption-based billing. Only in a few exceptions (e.g. passive houses below 15 kWh/m²/a, two-family houses with owner occupancy) may billing be entirely by area. If the landlord breaches this, the 15% reduction right applies.
What are reasonable heating costs per square meter?
According to Heizspiegel 2025, average heating costs for a 70 m² apartment are about €14.70/m²/year (gas), €17.50/m²/year (district heating), or €9.70/m²/year (heat pump). Values significantly above this may indicate poorly insulated buildings or billing errors.
Do metering-service costs (Techem, ista) have to appear in the bill?
Yes. Costs for device rental, reading, and billing are allocable. However, if metering-service costs are more than 15% of total heating costs, this is a warning sign for excessive costs that you can object to.