What are the consequences of selling a house below its cadastral value?

Real estate has a cadastral value, calculated as the income multiplied by 5 percent and a coefficient; this serves as the basis for taxes—registration, mortgage, and cadastral. The law does not require selling at a minimum price, but quoting a price below the cadastral value creates risks for both parties: tax audits and joint liability.

Under the price-to-value system, mandatory for individuals since 2006, taxes are always calculated based on the cadastral value, not the stated price, so the buyer doesn't save money and pays according to the cadastral value. However, if the price is too low, for example, less than 70 percent of the OMI, the tax office assumes unspecified payments and initiates a revaluation based on the OMI, mortgage, or appraisal, a recalculation of the seller's capital gain, and penalties ranging from 90 to 180 percent plus interest.

Let's take an example for 2025: a yield of 800 euros gives a cadastral value of 800 × 1.05 × 115.5 = 96,600 euros; if the declared price is 60,000 euros, a suspicious difference of 36,600 euros could lead to a revaluation and a fine of up to 65,880 euros.

The buyer bears joint and several liability and pays additional taxes and penalties, even if they paid little, while the seller faces a revaluation of the increase and personal income tax based on the actual amount, plus penalties.

To avoid inspections, it's safe to indicate a price no lower than the cadastral value, use the "price-to-value" mode, which is automatic for individuals, conduct an appraisal if the price is low due to objective reasons such as dampness or a nearby landfill, conduct only bank transfers, not cash, and when selling to relatives, indicate a symbolic price with a reasoned deed, taking into account the risk of indirect donation.

There is no minimum price by law due to freedom of contract, but the cadastral value remains the minimum tax base; the coefficients for 2025 are 110 for first-time homes and 120 for second and other properties.

During an audit, joint liability applies: the tax authority can collect from both parties through notification, payment, and forced collection.

Ultimately, a price reduction of 10–20 percent is usually low-risk if justified; a price reduction below 70 percent of the OMI is high and requires expert review and an experienced notary; and selling to children is medium-risk with a deed of nominal value and probate consultation. Useful links: Agenzia Entrate website for prezzo-valore and the OMI for 2025.