If you want to replace your old oil or gas boiler with a heat pump or another eligible system, you can get a large share of the costs back from the state. For this to work, you need to apply for the heating subsidy before any work begins on site, and in the right order. This is exactly where many applications fail: a contract signed too early without the right clause or a missing document can cost you the entire grant.
In this guide, we show you step by step how the application for KfW grant 458 works, which documents you need and which deadlines apply. We also summarise how the grant is made up, what changed in summer 2026 and which typical mistakes you should avoid. Status: October 2026. The current information published by KfW always takes precedence.
Which heating subsidies are available in 2026?
Funding for replacing a heating system is provided through the Federal Funding for Efficient Buildings (BEG). For private owners of residential buildings, KfW grant 458 is the relevant programme. Eligible systems include heat pumps, biomass heating, solar thermal systems and connection to a building or district heating network. Other individual measures, such as optimising an existing heating system, are handled by the Federal Office for Economic Affairs and Export Control (BAFA) instead. You can read what is required for hydraulic balancing in the guide Hydraulic Balancing 2026.
Amended conditions have applied to new applications since 21 July 2026. Anyone who applied before that date will be funded under the previous rules. According to KfW, the climate speed bonus and the maximum funding amount will gradually decrease from 1 February 2027. In addition, the Building Modernisation Act (GModG) came into force on 29 July 2026, abolishing the previous 65 per cent requirement for new heating systems. This does not change the funding logic: grants are still only available for the systems eligible under the BEG.
How the grant is made up
According to KfW, the heating subsidy consists of basic funding and up to two bonuses. The basic funding amounts to 30 per cent of the eligible costs. It is generally available to all private owners, including landlords. Owner-occupiers who replace a working old heating system can also receive the climate speed bonus. It currently stands at 16 per cent and will decrease by 4 percentage points every six months from 1 February 2027 until it expires in August 2028.
The income bonus depends on the taxable household income of owner-occupiers and has three tiers: 40 per cent up to 30,000 euros, 30 per cent up to 40,000 euros and 10 per cent up to 50,000 euros. According to KfW, households with children under 18 can deduct 10,000 euros from the income taken into account. Overall, the funding rate is capped: usually at 70 per cent, and at up to 80 per cent for low-income households.
For the first residential unit, costs of up to 28,000 euros are eligible. In addition to the heat generator, this includes related measures such as planning, removal of the old system, necessary adjustments to radiators and pipework, and hydraulic balancing. From February 2027, this maximum amount will fall by 750 euros every six months. Lower amounts per unit apply to further residential units in apartment buildings.
| Component | Amount according to KfW | Who can receive it |
|---|---|---|
| Basic funding | 30 % | Private owners, including landlords |
| Climate speed bonus | 16 %, decreasing from 01.02.2027 | Owner-occupiers replacing an old heating system |
| Income bonus | 10 to 40 % depending on income | Owner-occupiers with household income up to 50,000 euros |
| Total funding rate | at most 70 %, up to 80 % for low incomes | Depends on the combination of bonuses |
Applying for the heating subsidy: the steps in the right order
Step 1: obtain a quote and sign a conditional contract
First, you obtain a quote from a specialist contractor. You may sign the supply or service contract before applying, but it must contain a condition precedent or a condition subsequent. This means that the contract only takes effect, or only remains in force, if the funding is approved. Without such a contract, you cannot submit the application.
Step 2: have the confirmation for the application (BzA) prepared
Next, the contractor or an energy efficiency expert prepares the confirmation for the application. It documents the planned measure and the expected eligible costs and contains a BzA ID, which you need for the application. Check that the details match the contract.
Step 3: submit the application in the "Meine KfW" portal
You apply for the grant yourself online in the "Meine KfW" customer portal, not via your bank. After registering, you enter the BzA ID, add your personal details and provide information on your income if required. Work on site may only begin once the application has been submitted. Anyone who starts earlier loses their entitlement to funding. If you start after applying but before approval, you bear the risk of a rejection yourself.
Step 4: receive approval and install the heating system
After the review, you will receive the funding approval in the portal. According to KfW, you then have up to 36 months from approval to complete the project. During this phase, the contractor installs the new heating system, carries out hydraulic balancing and commissions the system.
Step 5: submit proof and receive the payment
Once the work is complete, the contractor or expert prepares the confirmation after completion (BnD). You upload this together with the invoices in the portal, and you also have to verify your identity. The deadline for submitting proof is stated in your approval. After a successful review, KfW pays the grant into your account.
Documents and technical requirements
- Quote and supply or service contract with a condition precedent or subsequent
- Confirmation for the application with BzA ID
- Proof of income if you apply for the income bonus
- Invoices, confirmation after completion and proof of hydraulic balancing
For heat pumps, the funding also sets technical requirements, for example regarding the noise emissions of the outdoor unit and the refrigerant used. The exact limits are set out in the KfW technical minimum requirements. Have the contractor confirm before signing that the planned unit is eligible. You can read what is technically possible in existing buildings in the guide Heat Pumps in Older Buildings.
Avoiding typical mistakes in the funding application
The most common mistake is a contract without a condition. Anyone who signs a normal order and only applies afterwards is excluded from funding. Starting work too early is just as critical, for example if the contractor removes the old boiler before the application has been submitted. Pure planning and advisory services, on the other hand, do not count as the start of the project.
Another stumbling block is discrepancies between the quote, the confirmation for the application and the final invoice. If the unit or the scope changes during the project, check with the contractor whether this affects the funding. Also keep an eye on the deadline for submitting proof. Finally, the heating subsidy cannot be combined with tax relief for the same measure. Our guide Heat Pump Funding 2026 answers the most important questions about heat pumps.
Frequently asked questions
Can I apply for the heating subsidy retrospectively?
No. The application must always be submitted before work begins on site. A heating system that has already been installed will no longer be funded through grant 458. Tax relief may still be an option in that case.
Do landlords also receive the heating subsidy?
Yes, the basic funding of 30 per cent is also available to landlords. The climate speed bonus and the income bonus, however, are reserved for owner-occupiers.
Can the grant and the tax bonus be combined?
Not for the same measure. You choose either the KfW grant or the tax reduction for energy-related renovation under Section 35c of the German Income Tax Act. Which option is better for you depends on your personal situation.
When is the grant paid out?
Only after the work has been completed and your proof has been reviewed. According to KfW, the grant can be combined with the supplementary loan 358 or 359 for interim financing.
Conclusion
Applying for the heating subsidy above all requires care with the order of steps. First come the quote and the conditional contract, then the confirmation for the application and the application in the "Meine KfW" portal. Only then does installation begin, and at the end you submit the proof. Because bonuses and maximum amounts will decrease from February 2027, early planning pays off. Before applying, check the current conditions directly with KfW. You will find suitable units and accessories for your project in our Heat Pumps and Heating categories.
