Anyone replacing an old oil or gas heating system with a heat pump in 2026 can receive a KfW 458 subsidy of up to 70 % of the eligible costs. For a single-family home that currently means up to 21,000 €.
From 21 July 2026 this calculation shifts. For households with a taxable income above 30,000 €, the maximum subsidy drops to 19,600 €, and it keeps falling every six months after that. The date of your application therefore decides several thousand euros.
This concerns many existing buildings from the 1990s and 2000s whose oil or gas boilers are now reaching the end of their usual service life. Around Wildau, Königs Wusterhausen, and Zeuthen there are plenty of houses like this.
The four building blocks of KfW 458
The heating grant is a KfW subsidy programme for owner-occupiers. It combines a base grant and three bonuses that are added together. The total never exceeds 70 % of the eligible costs.
| Building block | Rate | Condition |
|---|---|---|
| Base grant | 30 % | Installation of an eligible heating system, for example a heat pump, biomass, or connection to a heating network |
| Climate speed bonus | +20 % | Replacement of a still functioning oil, coal, gas, or night-storage heating system, owner-occupiers only |
| Efficiency bonus | +5 % | Heat pump using a natural refrigerant or ground, water, or wastewater as its heat source |
| Income bonus | +30 % | Taxable household income of up to 40,000 € per year |
Only those who combine all three bonuses reach the full rate. An owner-occupier on a low income who swaps an old oil boiler for an efficient heat pump adds up to 30 plus 20 plus 5 plus 30, or 85 %. The payout is still capped at 70 %.
For most owner-occupiers the base grant and the climate speed bonus are the norm, 50 % together.
What counts as an eligible heating system
Funding covers the switch to a system that runs mainly on renewable energy. That includes heat pumps, biomass systems, solar thermal, and connection to a heating network. Simply repairing an existing fossil-fuel heater gets nothing from KfW 458.
Why 21 July 2026 matters
The eligible costs for a single-family home stand at 30,000 €. At 70 % funding that comes to up to 21,000 € in subsidy. On 21 July 2026 this ceiling is lowered for households with a taxable income above 30,000 €.
- Until 20 July 2026: up to 21,000 € subsidy, that is 70 % of 30,000 €
- From 21 July 2026: at most 19,600 € for households with taxable income above 30,000 €
- After that, falling further every six months, down to around 13,200 € by 2030
If you are planning the replacement anyway, file the application before the cut-off date. For a planned heat pump the date alone makes a difference of 1,400 €. What counts is the date of the application. Check the exact cut-off rules before applying, as the details can change at short notice.
In practice, several weeks pass between the first quote and the submitted application. A specialist firm has to inspect the building, estimate the heating load, and write a solid quote before the contract with the condition precedent is in place. If you still want to catch 21 July 2026, do not leave the process to the last week.
Two income thresholds show up here that have nothing to do with each other. The 30 % income bonus applies at a taxable household income of up to 40,000 €. The reduction of the maximum from 21 July 2026 hits households above 30,000 €. Anyone in between, at 35,000 € for instance, still gets the bonus but on the lower ceiling.
Apply before you hire
The subsidy is only granted if the application reaches the KfW before the work begins. Anyone who hires the installer first and thinks about funding afterwards goes away empty-handed.
To make both fit together, the contract with the executing company is signed subject to a condition precedent. The order only counts as concluded once the funding approval is in hand. This way the contract is documented early enough for the cost calculation without the work having begun in the eyes of the KfW.
A heating swap rarely stands alone
A new heat pump only runs economically if the building envelope plays along. In a poorly insulated older building with old windows it needs high flow temperatures and uses a lot of electricity.
KfW 458 is only about the heating system. Insulating the top-floor ceiling, new windows with a U-value of 0.95 W/(m²K), or an insulated facade run through other funding pots. Measures like these can be bundled in time so the site is set up once rather than year after year.
That is why the heating swap often comes at the end of a larger renovation, together with insulation, windows, and a renewed facade. For these works the BAFA grant for individual measures offers separate subsidies, and the tax break under section 35c of the Income Tax Act lets you check what pays off without a KfW application.
We have coordinated renovations like this several times, most recently for the Berlin Workshops for People with Disabilities, where we fully gutted an existing building, renewed the roofs, and brought the facade up to current energy standards. As a turnkey and renovation contractor, we plan the heating swap as part of the overall schedule and coordinate it with the other trades.
How to sort out your case
Whether it pays to apply before 21 July for your project, and how KfW 458, BAFA grants, and the tax break split up sensibly, is something we work out in a free initial consultation. You will find an overview of all programmes on our funding page.
Call us on +49 3375 95 09 70 or write to us via the contact form. We build across Berlin and Brandenburg within roughly 50 km of Wildau.
