Income bonus: what your income adds to the German heating grant
The income bonus rests on two German tax assessments and on who is registered at the address. This page shows how KfW works out the figure and what it accepts as proof.
Worked through by Radif Partners · Editorial policy · How we calculate
Your income bonus
Income bonus
40 %
| Income counted | €28,000 |
| Overall ceiling | 80 % |
| Grant on €28,000 (gas, 20 years) | €22,400 |
The income bonus (Einkommensbonus) is a top-up on the KfW 458 heating grant for owners who live in the house or flat as their main residence. It is 40 % up to €30,000 of taxable household income, 30 % up to €40,000 and 10 % up to €50,000. KfW takes the average from the tax assessments for the second and third year before you apply, so 2023 and 2024 for a 2026 application. If a child under 18 with a child benefit entitlement lives with you, KfW counts €10,000 less, once. Together with the basic grant and the climate bonus the rate is capped at 70 %, or 80 % up to €30,000. A couple with €36,000 and €42,000 on their two assessments averages €39,000 and receives €19,600 for a €30,000 heat pump replacing a 25-year-old gas boiler. With a child in the household they move down one band and get €22,400.
Who gets the income bonus
The bonus is only for owners who live in the home being funded, and only for that one home. You count as an owner-occupier if, when KfW receives the application, you are registered there as your main or only residence; ownership is shown by the land register extract (Grundbuchauszug). A property you let out receives the basic grant but no income bonus (grants for landlords). In an owners' association each owner-occupier claims the bonus through an additional application linked to the association's own (heating grant in a WEG). A holiday home or a house you keep while working abroad does not qualify, because it is not your main residence.
The bonus funds the same heating replacement as the basic grant: heat pump, biomass, solar thermal, fuel cell or connection to a heat network. The rules are in no. 8.4.5 of the BEG EM guideline of 17 August 2026 and on pages 4 and 5 of information sheet 458, both in German only.
Three bands and the family allowance
Until 20 July 2026 there was a single band: 30 % up to €40,000. Since 21 July 2026 the bonus has three bands, and for families every limit moves up by €10,000. The right-hand column shows the most a single-family house replacing an oil boiler can receive when costs exceed the €28,000 cap.
| Income, no child | with child | Bonus | Total rate | Grant at most |
|---|---|---|---|---|
| up to €30,000 | up to €40,000 | 40 % | 80 % | €22,400 |
| up to €40,000 | up to €50,000 | 30 % | 70 % | €19,600 |
| up to €50,000 | up to €60,000 | 10 % | 56 % | €15,680 |
| above €50,000 | above €60,000 | 0 % | 46 % | €12,880 |
In the first band the basic grant, climate bonus and income bonus would add up to more than 80 %, and the ceiling cuts off the rest. In the second band the general 70 % ceiling applies. Without the climate bonus, for example because the gas boiler is under 20 years old, the income bonus alone reaches the ceiling less often.
How KfW works out household income
The starting point is taxable income (zu versteuerndes Einkommen) as printed on the German income tax assessment, not gross salary. It is the figure after work expenses, special expenses and allowances. According to the ministry’s questions and answers, it does not matter whether the tax office deducted child allowances. The household is every owner registered at the home on the application date, plus their spouse or partner registered there. Their incomes are added up per year, then KfW averages the second and third calendar year before the application.
For a 2026 application that means 2023 and 2024. By the same rule a 2027 application would use 2024 and 2025, though KfW has not yet published an example for that year. For separated spouses who were still assessed jointly, half of the joint income counts. Income earned abroad is included. The special rule in section 2(5a) of the Income Tax Act, which would add back certain capital income, is expressly not applied. If you file jointly in Germany but your partner lives abroad and is not registered at the home, only the registered owners count.
Five households, recalculated
| Household | Counted | Bonus | Grant |
|---|---|---|---|
| Couple, assessments €36,000 and €42,000, 25-year-old gas boiler, €30,000 heat pump | €39,000 | 30 % | €19,600 |
| the same couple with a seven-year-old child | €29,000 | 40 % | €22,400 |
| Retired owner, €24,000, oil boiler, €26,000 heat pump | €24,000 | 40 % | €20,800 |
| Family, €55,000, one child, 25-year-old gas boiler | €45,000 | 10 % | €15,680 |
| Single owner, €45,000, gas boiler only 12 years old | €45,000 | 10 % | €11,200 |
For the retired owner the cost is below the cap, so the 80 % rate applies to the full €26,000. In the last case there is no climate bonus, leaving 30 % basic grant and 10 % income bonus. For the couple, the child adds €2,800, because the allowance shifts both the band and the ceiling.
Grant for your house
Grant
€15,680
| Grant rate | 56 % |
| Eligible costs | €28,000 |
| Your share | €16,320 |
Applying now, heat pump, guideline of 17 Aug 2026.
What KfW wants as proof
Income is checked not when you apply but when you submit evidence after installation. You then upload to the “Meine KfW” portal the tax assessments for both years for yourself and every adult household member who counts, the registration certificates of everyone counted (and of the child for the family allowance), and a land register extract naming all relevant owners. KfW does not accept payslip summaries (Lohnsteuerbescheinigung) or pension notices. For applications with an income bonus under the 07/2026 version of the information sheet, submitting evidence is expected to open from January 2027, according to the sheet.
You choose the bonus in the application itself. According to the KfW product page, changing the bonus afterwards is generally not possible. If you are unsure which band you fall into, run the grant calculator first and put your two assessments next to the limits in the table above.
The bonus and your application date
The income bonus rates stay the same until the guideline ends. What falls is the cap on eligible costs and the climate speed bonus. The couple with a child would receive €21,800 instead of €22,400 if they applied from 1 February 2027. In the first band the difference is small, because the ceiling already trims part of the climate bonus. For the rest of the bill, the top-up loan offers an interest discount with its own, higher income limit of €90,000. The steps are under how to apply, the full programme under KfW 458.