CO2 Cost Allocation in 2026: A Phased Approach and Obligations for Landlords

As of January 1, 2023, the CO2 Cost Allocation Act (CO2KostAufG) no longer requires tenants to bear the full burden of the annually increasing CO2 levies on fossil fuel-based heating energy. Landlords in the Nuremberg metropolitan region bear between 0 and 95 percent of the costs, depending on the building’s energy efficiency-an obligation that must be recalculated with every heating bill and carries significant consequences if neglected.

What the CO2KostAufG regulates-and why it particularly affects landlords

The CO2 tax on heating oil, natural gas, and other fossil fuels has been rising in stages since 2021. By 2026, it will reach 55 euros per ton of CO2. The federal law from 2022 aims to incentivize landlords to renovate energy-inefficient buildings: Those who rent out a poorly insulated house bear the lion’s share of the CO2 tax themselves. Those who modernize automatically reduce their burden.

The law applies to all residential buildings with a central heating system powered by natural gas, heating oil, liquefied petroleum gas, or coal. Separate regulations apply to residential buildings where tenants settle heating costs directly with the utility provider. District heating is generally exempt as long as the district heating provider passes on the CO2 costs itself.

Important for landlords in Nuremberg, Fürth, and Erlangen: The obligation to calculate the tax lies solely with the landlord. They must include the correct CO2 landlord share in every annual heating cost statement and withhold it from the tenant. If this breakdown is missing, the statement is considered formally incorrect.

The 10-Step Model: CO2 Emissions Determine Cost Allocation

The following table shows the official emission classes according to the CO2KostAufG and the resulting cost allocation. A 100-m² apartment in Nuremberg with a gas consumption of 12,500 kWh/year (typical for an older building constructed in 1970) and a CO2 price of €55/t serves as a calculation example.

Level	CO2 Emissions (kg/m²/year)	Tenant Share	Landlord Share	Example CO2 Costs for 100 m² (€/year)	Of which Landlord (€)
1	< 12	100%	0%	~55	0
2	12-17	90%	10%	~70	7
3	17-22	80%	20%	~85	17
4	22-27	70%	30%	~100	30
5	27-32	60%	40%	~115	46
6	32-37	50%	50%	~130	65
7	37-42	40%	60%	~145	87
8	42-47	30%	70%	~160	112
9	47-52	20%	80%	~175	140
10	> 52	5%	95%	~190+	~180+

Source: CO2 Cost Allocation Act (CO2KostAufG) Annex 1, Federal Environment Agency CO2 Price Path 2026. Calculation example: own calculation based on Federal Network Agency emission factors, as of Q1 2026.

The CO2 emission value is derived from the building’s energy performance certificate or-more precisely-from the actual consumption bill for the previous year. For an unrenovated Wilhelminian-style building in Nuremberg’s Gostenhof with 65 kg CO2/m²/year, Level 10 means: The landlord pays nearly 180 euros per apartment out of pocket each year solely as a CO2 levy.

Obligation to Calculate with Every Heating Bill

Landlords cannot simply set the CO2 costs once and then forget about them. Since the price of CO2 rises annually and actual energy consumption changes from year to year, the calculation must be redone with every heating bill. In practice, this means:

• The building’s CO2 emissions are determined using the fuel bill and the emission factors from the Federal Environment Agency.
• The emission value is divided by the heated living area (not the gross floor area!).
• The landlord’s share is calculated in euros using the tier table.
• The landlord’s share is deducted from the total CO2 tax amount and shown separately on the bill.

> The valuation tool from leadmarkt.ch provides an initial assessment of your property’s energy efficiency and thus its value-data-driven and ready in just a few minutes.

For landlords managing multiple units in a Nuremberg apartment building, we recommend the free CO2 tax calculation provided by the DENA calculation tool (dena.de/co2kostenaufteilung). This tool automatically determines the emission class and the correct share based on the energy bill.

Penalties for Failure to Comply and Tenant Challenges

An incorrectly calculated or missing CO2 certificate in the heating cost statement has several consequences. The tenant may reduce the total heating cost statement by 3 percent, even if the error affects only the CO2 item-just as with other violations of the Heating Cost Ordinance. In addition, the tenant can demand a correction and reclaim overpaid amounts retroactively for the standard three-year statute of limitations.

Tenants’ associations in Nuremberg and Fürth-particularly the Mieterverein Nürnberg e.V.-are actively informing members about the CO2KostAufG and checking bills for completeness. Landlords who have not yet included a separate CO2 line item in their bills should have the bills for the years 2023 through 2025 reviewed retroactively.

GEG Renovation Obligation and CO2 Pressure: The Interconnection

The CO2KostAufG does not operate in isolation. It is closely linked to the Building Energy Act (GEG) and the Building Modernization Act (GModG). Anyone operating a building in energy efficiency class 9 or 10 not only pays the high landlord share of the CO2 levy-they are also obligated, in the event of a change of ownership or a comprehensive renovation under GEG § 47, to significantly improve the energy standard.

Starting in November 2026, the stricter GModG requirements will take effect: For complete renovations and roof replacements, buildings must achieve at least energy efficiency class D. For owners in the Nuremberg metropolitan region with older buildings constructed between 1950 and 1975-which often fall into levels 8 through 10-this means: The financial pressure from CO2 taxes and renovation obligations is increasing at the same time.

Those who invest now in exterior wall insulation, window replacement, or a heating system upgrade can lower the building’s emission class and thus immediately move into a lower cost tier. A calculation example: A Nuremberg apartment building with four 80-square-meter units that is renovated from Level 9 to Level 4 will save the landlord approximately 500 to 700 euros in CO2 costs per year starting in 2026-plus the KfW subsidy, which reduces renovation costs by 15 to 25 percent.

Practical Implementation: How the CO2 Component Is Included in the Heating Cost Statement

The CO2 cost allocation does not need to be billed separately-it is integrated into the heating cost statement already required by the Heating Cost Ordinance (HeizkostenV). For landlords who work with a heating cost billing service (Techem, Ista, Minol, etc.), these providers now offer automated CO2 cost allocation. Those who prepare the bill themselves can find free support in the DENA calculation tool at dena.de/co2kostenaufteilung.

The process in detail: The fuel supplier reports the included CO2 tax in its annual statement. The total emissions of the building are calculated using the emission factor of the respective fuel (e.g., natural gas: 0.201 kg CO2/kWh according to the Federal Environment Agency). Dividing this by the heated living area yields the specific emission value in kg CO2/m²/year. This value determines the tier classification and thus the landlord’s share of the CO2 tax.

The challenge for landlords lies in data collection: Those who do not have an energy audit and do not know the building’s living area precisely may end up in the wrong tier. Incorrectly calculated CO2 shares-whether too high or too low-require subsequent correction. It is therefore worthwhile to conduct a thorough one-time building data collection and update it annually.

Local Characteristics: Older Neighborhoods with High Renovation Needs

In the Nuremberg metropolitan region, there are distinct older neighborhoods that particularly often fall into the high CO2 tiers. Nuremberg’s Gostenhof district with its Wilhelminian-style apartment buildings, the Fürth Südstadtgürtel, and older apartment blocks in Erlangen-Bruck are typical areas where landlords will bear up to 95 percent of the CO2 tax in 2026 without renovation. In Schwabach, too, the Old Town Ring and along Nuremberg’s Ringstraße feature numerous unrenovated Wilhelminian-style buildings for which the tiered model entails significant annual additional costs.

The appraisal committees of the cities of Nuremberg, Fürth, and Erlangen note in their 2024/2025 annual reports that energy-inefficient residential buildings (Classes E-H) already command significant price discounts of 8 to 18 percent compared to comparable renovated properties. The CO2 cost burden further exacerbates this trend. For landlords, the message is clear: The CO2 price, currently 55 euros per ton, will continue to rise according to the Federal Climate Protection Act-to 65 euros in 2027 and an estimated 85-100 euros by 2030. Those who remain in Level 10 now will pay significantly more out of pocket with each passing year.

Common mistakes in CO2 cost allocation-and how to avoid them

During the first practical phase since 2023, several typical sources of error have emerged in the Nuremberg metropolitan region. The most common: Landlords use the living space specified in the lease as the basis for calculation instead of the heated living space of the entire building. If the stairwell is heated but not included in the heated area, this distorts the emissions calculation-and thus the tier classification.

Another mistake: Fuel bills sometimes include multiple energy sources (e.g., gas + heating oil from transitional stock). Those who apply only one emission factor risk arriving at an incorrect total CO2 amount. The emission factors from the Federal Environment Agency are listed separately for each energy source and must be allocated proportionally.

Finally: heat supply contracts. Those who receive district heating or contracting often have their CO2 allocation assigned in advance by the supplier. In this case, a double CO2 calculation may occur. The supplier must explicitly confirm whether the CO2 costs in their bill have already been allocated in accordance with the CO2 Cost Allocation Act (CO2KostAufG) or whether the landlord must perform the allocation themselves.

Conclusion for Landlords in Middle Franconia

By 2026, the CO2 tiered model will no longer be a mere bureaucratic footnote-it will be a tangible cost factor that must be recalculated with every heating bill. Landlords with high emission classes in unrenovated older buildings are already paying substantial amounts out of pocket today. The price of CO2 will continue to rise through 2030. Those who renovate now not only reduce their own share of the costs but also increase the property’s market value.

The combination of CO2 cost pressures and the renovation obligations under the GEG and GModG makes an active renovation roadmap an economic necessity for all landlords with older properties in the Nuremberg metropolitan region-not just a voluntary climate protection measure. Those who act early will benefit from KfW funding still available and increased rental income from energy-efficient properties.

Before making concrete investment decisions, it’s worth taking a look at the valuation tool from leadmarkt.ch - it takes energy efficiency features into account and provides a data-driven assessment of which renovation measures will actually increase the property value in your location.

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Created by the my-home.de editorial team in collaboration with regional real estate analysts. Data as of May 2026.