Polish homeowners can deduct thermal modernization costs up to 53,000 PLN, but must claim them in the year expenses occurred or within six years.
Thermal Modernization Tax Deduction
The thermal modernization tax deduction is available to owners and co-owners of single-family homes. Each taxpayer (owner or co-owner) can deduct expenses for thermal modernization up to 53,000 PLN – these must be documented with invoices from an active VAT taxpayer, i.e., with VAT amount. The list of these expenses is specified in the regulation of the Minister of Investment and Development of December 21, 2018, on determining the list of types of construction materials, equipment, and services related to the implementation of thermal modernization projects (as amended: Journal of Laws of 2025, item 1128). Therefore, one can deduct in an annual return, for example, the costs of window replacement, or replacing an old furnace with a boiler designed exclusively for biomass combustion.
PIT. The Moment of Claiming the Deduction
A reader – a retiree – asked whether he and his wife, who had saved for several years to replace windows in their house, could claim the deduction. He explained that in 2025, they do not have sufficient income from their pensions to claim the deduction. It is lower than the tax-free amount of 30,000 PLN. However, in 2026, he took up employment and expects to have taxable income. He heard that the deduction can be claimed over six years. He asked whether costs amounting to 27,000 PLN could be deducted in the following year.
Deducting Costs in the Annual PIT
“No, because the law does not allow the deduction to be claimed at any time within six years,” says the chief tax advisor at InFakt. According to Article 26h, paragraph 6 of the PIT Act, deductions are made in the declaration for the tax year in which the expenses were incurred (the date of the invoice determines this). Only if there is not enough income to claim the deduction can the deduction be carried forward to subsequent years, but not longer than six years, counting from the end of the tax year in which the first expense was incurred (Article 26h, paragraph 7 of the Act).
Whether the reader will be able to reduce his income in the 2026 return depends on what income he had in 2025. Piotr Juszczyk illustrates this in the following example.
