CO₂ costs: does the landlord pay too? (CO2KostAufG 2026)

What is the CO₂ cost split?

Fossil fuels such as natural gas and heating oil carry a CO₂ price in Germany — and it sits inside your heating bill. Tenants used to pay this surcharge alone. Since 1 January 2023 the Kohlendioxidkostenaufteilungsgesetz (CO2KostAufG) (carbon-cost allocation act) has changed that: tenants and landlords share the CO₂ costs.

The most important fact first: for residential buildings a 10-step model (§ 5 CO2KostAufG) decides who pays how much. The logic is fair — the worse a building is insulated and the more CO₂ it emits, the larger the landlord's share, because the landlord controls the insulation and the heating system.

The 10-step model for residential buildings (§ 5 CO2KostAufG)

What matters is the CO₂ emissions per square metre of living space per year. Depending on the value, one of ten steps applies:

CO₂ emissions (kg/m²/year)	Tenant share	Landlord share
52 and above	5 %	95 %
47 to < 52	20 %	80 %
42 to < 47	30 %	70 %
37 to < 42	40 %	60 %
32 to < 37	50 %	50 %
27 to < 32	60 %	40 %
22 to < 27	70 %	30 %
17 to < 22	80 %	20 %
12 to < 17	90 %	10 %
under 12	100 %	0 %

Rule of thumb: poorly insulated building = high landlord share. If you live in an energy-efficient new build, by contrast, you bear the CO₂ costs alone.

Your strongest lever: a 3 % reduction (§ 7 Abs. 4 CO2KostAufG)

It is the landlord who must calculate and deduct the share — not you. If the landlord fails to do so, or doesn't supply the necessary figures, you have a reduction right:

Achtung: If the landlord does not bill the CO₂ split, or does so without the required information, you may reduce your share of the heating costs by 3 % (§ 7 Abs. 4 CO2KostAufG). Assert the reduction actively and in writing to the landlord.

Step by step: how to check your share

1. Look for the split. Is a CO₂ cost split shown in the Heizkostenabrechnung at all? If not, your 3 % reduction right applies.
2. Check the emissions. Which value (kg CO₂/m²/year) is used, and which step does it fall into?
3. Compare the step. Match the assigned step and landlord share against the table above.
4. Verify the deduction. Was the landlord's share actually deducted from your heating costs — or merely shown but not offset?
5. Mind the deadlines. As with any Nebenkostenabrechnung you have 12 months from receipt to raise objections in writing (§ 556 Abs. 3 BGB).

Residential vs. non-residential buildings

	Residential	Non-residential (commercial)
Allocation	10-step model (§ 5 CO2KostAufG)	50/50 split (§ 8 CO2KostAufG)
Landlord share	0–95 %, by CO₂ emissions	50 %
Planned from 2025	–	own step model

Common mistakes

• No CO₂ split in the statement — although mandatory since 2023.
• Wrong step — the CO₂ emissions are understated, making the landlord's share too small.
• Share shown but not deducted — the relief never actually reaches you.
• Reduction right unused — you don't claim the 3 % under § 7 Abs. 4 CO2KostAufG.

HausMaus makes it easier

HausMaus is free for tenants and helps you check your Heizkosten- and Nebenkostenabrechnung item by item — including whether the CO₂ cost split under the CO2KostAufG is present and the landlord's share has been correctly deducted. The app shows you the 12-month deadline under § 556 BGB and, on request, drafts the matching objection if the split is missing or wrong. Wohnen, geregelt.

See pricing – free for tenants →