The Italian Revenue Agency ruled in Response No. 158 that owners selling Superbonus-upgraded property cannot use co-owner construction costs to reduce their capital gain, confirming that tax relief under Articles 67–68 of the Income Tax Code applies only to the owner who actually financed the work. 

The Italian Revenue Agency clarified on 10 August 2026 through Response No. 158 that owners selling property upgraded through the Superbonus cannot claim construction costs paid by their co-owners to reduce their taxable capital gain.

The ruling clarifies how the new capital gains tax—introduced by the 2024 Budget Law and governed by Articles 67-68 of the Income Tax Code (TUIR)—applies when property ownership is split and improvements are financed by only one owner.

The case involved a mother and daughter holding inherited and purchased shares in a property that underwent Superbonus renovations between 2021 and 2023. The son financed all 110% tax-credit work and claimed the benefits himself. Now selling their shares, the mother and daughter asked whether they could add his construction costs to their tax basis to reduce their own capital gain. The Agency said no.

Only inherited shares escape the new tax

Properties acquired through inheritance remain exempt from the capital gains tax introduced in the 2024 Budget Law. When ownership is mixed—part inherited, part purchased—the exemption applies only to the inherited portion. The taxable capital gain is calculated separately for each ownership interest. The Agency’s position, restated from Response No. 208/2024, makes clear that the exemption does not extend to shares purchased for cash.

The Agency also confirmed that a sworn property appraisal can serve as the cost basis when original purchase or construction documents no longer exist (Response No. 86/2026). This matters because many properties upgraded years ago lack full documentation.

The cost belongs to the owner who paid it

Here is the crux. Article 68 of the TUIR allows property costs to be added to the tax basis when calculating gain. But the law limits this benefit to expenses actually incurred by the selling owner. Since the mother and daughter paid nothing for the Superbonus work, they cannot increase their basis using the son’s outlays. The property improvements are real. The tax relief is not transferable between owners.

This is where timing intersects with treatment. Eligible Superbonus costs receive different tax coverage depending on when the sale occurs:

• Sold within 5 years of work completion: construction costs are excluded from the capital gain calculation entirely.
• Sold after 5 years: 50% of eligible expenses are included as part of the property’s cost basis.

In this case, the sale occurs in 2026, well beyond five years from the 2021–2023 work period. The mother and daughter would benefit from the 50% cost inclusion only if they personally financed part of the work. Since they did not, the rule does not apply to their shares.

An alternative for specific taxpayers

The 2024 Budget Law (paragraph 66, Article 1, Law No. 213/2023) preserves the option of a 26% substitute tax. Taxpayers meeting the conditions can elect this flat rate instead of calculating capital gain under the standard rules, offering certainty in cases where the conventional method yields higher liability.