Heating Replacement Funding 2026: KfW Subsidies for German Landlords

If your rental property’s heating system is approaching the end of its life, or you’re staring at a Sonderumlage decision in your WEG, understanding the 2026 KfW heating subsidy programme is one of the most consequential financial decisions you’ll make as a landlord. Get it right and you can fund 35% of the equipment cost and pass on 10% of the residual cost to tenants. Get it wrong and you leave thousands of euros on the table or, worse, install a heating system that’s no longer eligible for subsidies under the rules that took effect this year.

This guide walks through everything a private landlord needs to know about KfW programme 458 (Heizungsförderung für Privatpersonen, Wohngebäude) in 2026, including the catches that don’t appear in the marketing brochures.

The headline number is misleading

You’ll see “up to 70% subsidy” plastered across every heat pump installer’s website. That number does not apply to landlords. It’s the maximum a low-income owner-occupier can claim by stacking every available bonus.

For a private landlord renting out the property, the realistic maximum is 35% of eligible costs:

• 30% Grundförderung (base subsidy), available to everyone, including landlords.
• 5% Effizienzbonus, for heat pumps using natural refrigerants (e.g., propane R290) or brine/water (geothermal) heat pumps.

The two largest bonuses are explicitly closed to landlords:

This is the single most misunderstood point in the BEG programme. The 70% figure exists. It just isn’t yours.

Eligible costs are capped per unit

The KfW doesn’t subsidise an unlimited spend. It applies a maximum eligible cost ceiling per residential unit:

Example calculation for a 10-unit Mehrfamilienhaus:

Unit 1:        €30,000
Units 2-6:    €75,000  (5 × €15,000)
Units 7-10:   €32,000  (4 × €8,000)
─────────────────────
Total cap:   €137,000

If the actual heating system upgrade costs €120,000 in this 10-unit building, the entire amount is eligible. At a 35% landlord subsidy rate, you’d receive €42,000 from KfW.

If costs run to €180,000, only €137,000 is eligible. Your subsidy is capped at €48,000 (35% of €137,000), and you bear the full €43,000 above the ceiling yourself.

What’s actually covered

The eligible costs aren’t limited to the heating unit itself. KfW 458 covers:

• The heating equipment (heat pump, biomass boiler, solar thermal, district heating connection, fuel cell, etc.)
• Installation labour
• Deinstallation and disposal of the old system
• Drilling for ground heat probes (for geothermal systems)
• Replacement of radiators or installation of underfloor heating to make the new system work
• Buffer tanks, hydraulic balancing, and control systems
• Energy consultant fees (Energieeffizienz-Experte)

This is a meaningful detail: the radiator replacements that low-temperature heat pumps often require are themselves subsidised. You don’t have to absorb that cost separately.

Eligible heating systems

KfW 458 covers any heating system that meets the 65% renewable-energy rule under the current GEG:

• Heat pumps (air-water, brine-water, water-water)
• Biomass heating (pellet, wood chip, with strict particulate emission limits)
• Solar thermal
• Connection to a district heating network (Fernwärme), including biogas networks
• Hybrid systems combining renewables with a backup gas/oil unit
• Fuel cell heating (Brennstoffzellenheizung)

What’s not subsidised: pure gas or oil heating, even if highly efficient. The Gebäudemodernisierungsgesetz expected mid-2026 may abolish the 65% rule, but as of April 2026 the rule still applies for funding purposes.

The new 10 dB noise rule (effective January 1, 2026)

This is a recent change that has caught many installers and landlords off guard. From January 1, 2026, air-source heat pumps must be at least 10 dB below the EU sound power limit to qualify for KfW funding (previously: 5 dB).

In practice, this rules out a significant portion of mid-range air-source heat pumps. Before signing a contract, verify with your installer that the specific outdoor unit on the quote meets the new threshold. If you ordered equipment in 2025 but install in 2026, the 2026 rules apply at the date of subsidy application.

This change does not affect ground-source (geothermal) heat pumps, which already operate well below the threshold.

The new § 559e BGB: 10% rent surcharge with subsidy deduction

Until 2024, landlords could add 8% of modernisation costs to the annual rent under § 559 BGB. For heating replacements, the new § 559e BGB (effective January 1, 2024) introduced a separate, more landlord-favourable mechanism:

10% of net heating modernisation costs can be added to the annual rent, but with two mandatory deductions:

1. Subtract the KfW subsidy received (the actual amount, not the eligible base).
2. Subtract a 15% Erhaltungskostenpauschale (maintenance flat rate) representing the portion considered routine repair, not improvement.

Cap: The total resulting rent increase from a heating replacement cannot exceed €0.50 per m² per month, applied for six years.

Worked example

A landlord installs a €40,000 heat pump in a 4-unit building with a total of 280 m²:

Heating cost (gross):                  €40,000
Less: KfW subsidy (30% base):         -€12,000
Less: Maintenance flat rate (15%):     -€6,000
─────────────────────────────────────────────
Modernisation base:                    €22,000
× 10% annual surcharge:                 €2,200/year
÷ 280 m² ÷ 12 months:                   €0.65/m²/month

Capped at:                              €0.50/m²/month
Annual cap (280 m²):                  €1,680/year
Six-year total:                       €10,080

In this case, the cap costs the landlord €520 per year (€3,120 over six years). If you can structure the build so the per-m² figure stays under €0.50, you capture the full surcharge. Above that threshold, the cap kicks in and the rest is non-recoverable.

Application process: step by step

The KfW 458 process has tight sequencing. You must apply before signing a binding contract. This is the single most common reason for application rejection.

Step 1: Engage an energy efficiency expert or qualified contractor

You cannot file a KfW 458 application yourself. You need a Bestätigung zum Antrag (BzA), a confirmation document signed by either:

• A registered Energieeffizienz-Experte (listed on the dena Expertenliste), or
• A qualified Fachunternehmen registered in the Energie-Effizienz-Experten-Liste für Fachunternehmen.

The BzA confirms the planned heating system, the eligible costs, and that the technical minimum requirements are met.

Step 2: Sign a conditional contract

You need a delivery or installation contract in place, but it must explicitly state that it only takes effect once KfW approves the funding. This protects you from being locked into a contract before the subsidy is confirmed.

Step 3: Submit the application via “Meine KfW”

Log into the KfW customer portal at kfw.de, fill in the application using the BzA data, and submit. KfW typically responds within a few weeks.

Step 4: Execute the work (within 3 years)

Once you have the funding commitment (Förderzusage), you can proceed with the installation. KfW gives you three years to complete the project.

Step 5: Bestätigung nach Durchführung (BnD)

After the system is installed and commissioned, the energy expert or contractor produces a Bestätigung nach Durchführung confirming the installation matches the application.

Step 6: Identity verification and disbursement

Submit the BnD plus required documents (invoices, identity verification) via the portal. KfW disburses the subsidy directly to your bank account.

Strategic implications: when does it make sense?

Even with the 35% landlord subsidy, a heating replacement is rarely a positive-NPV decision in pure cash terms, especially compared to repairing an existing functional boiler. The economics shift in your favour when you account for:

1. The CO2KostAufG cost share. Under the new CO2 cost-sharing law, a landlord with an inefficient gas heating system bears 50–95% of CO2 costs (potentially €200–€600/year per unit). A heat pump cuts this share to 0–10%. Over a 15-year horizon, the avoided CO2 costs can fund a significant portion of the upgrade. Use our rental yield calculator to model this.

2. AfA depreciation on the unsubsidised portion. The heating system is added to the building basis and depreciated. Use our AfA calculator to model the tax effect at your marginal rate.

3. Property value uplift. Energy-efficient buildings command higher sale prices and lower vacancy. Properties with poor energy ratings (F/G) increasingly trade at meaningful discounts.

4. GEG forced replacement timing. If your boiler fails after the 65% rule applies in your municipality (post-Wärmeplan), you have no choice. Voluntary replacement at a moment of your choosing is cheaper than emergency replacement.

5. The § 559e rent surcharge. Even capped at €0.50/m²/month for six years, the surcharge offsets a non-trivial share of the unsubsidised cost.

What about the Gebäudemodernisierungsgesetz?

The CDU/CSU-SPD coalition agreed in February 2026 to replace the GEG with a new Gebäudemodernisierungsgesetz, expected by mid-2026. The headline change is that the 65% renewable-energy rule will be abolished, restoring the freedom to install gas or oil boilers (with restrictions returning in 2029).

Does this kill the case for a heat pump? Not necessarily, for two reasons:

1. KfW funding remains tied to renewable systems. A gas boiler will not be subsidised even after the GEG is replaced.
2. The CO2 cost share continues to penalise inefficient heating regardless of the GEG.

If you’re at the decision point now, it likely makes sense to proceed under the existing rules rather than wait. The new law’s exact provisions are not yet final, and your boiler is unlikely to wait for them.

Common mistakes to avoid

• Signing the contract before applying. This permanently disqualifies you from funding. The contract must be conditional on approval.
• Assuming the 70% headline applies to you. It doesn’t. Plan around 35% maximum.
• Forgetting to deduct the subsidy from the modernisation surcharge. § 559e BGB requires it. Failing to do so makes the rent increase legally challengeable.
• Buying an air heat pump before checking the 10 dB rule. A unit ordered in late 2025 may install fine but fail the 2026 funding criteria if the application is dated in 2026.
• Skipping the Energieeffizienz-Experte. You cannot self-file a KfW 458 application. The BzA is mandatory.
• Letting the 3-year completion window lapse. Funding commitments expire if the project isn’t completed in time.

Quick reference: KfW 458 for landlords in 2026

The bottom line

The KfW heating subsidy in 2026 is meaningful for landlords, up to 35% of eligible costs, plus the right to pass on 10% of the residual to tenants under § 559e BGB. But it’s far less generous than the 70% headlines suggest, the eligibility rules tightened in January with the 10 dB noise threshold, and the application process must be sequenced carefully to avoid disqualification.

For most landlords with a functional heating system, the rational play is to plan the upgrade now so you can move quickly when the boiler fails or the WEG triggers a Sonderumlage, rather than scrambling under emergency conditions. Use our mortgage calculator to model the financing of any unsubsidised portion, and the AfA calculator to capture the tax depreciation that comes alongside the subsidy.