The first step in understanding property taxation and reporting is to know what the cadastral value represents and how it is formed. In practical terms, the calculation always begins from the rendita catastale, which must be increased by a statutory factor of 5% and then multiplied by a coefficient that depends on the purpose
of the valuation. This resulting figure becomes the taxable base used in several contexts, from municipal levies to registration duties in a transfer. Knowing when and which multiplier applies is essential to predict taxes and to prepare accurate documentation for a sale or succession.
Although the origin is the same, the number you arrive at for local taxes often differs from the number used in transfer procedures. The two calculations
diverge because they apply different coefficients after the 5% increase: the IMU computation uses one set of multipliers aimed at municipal taxation, while the price-value system that supports registration and transfer formalities uses another. It is also mandatory for parties to declare the actual sale price in deeds, even when an alternative cadastral-based value is shown for specific administrative purposes.
How the calculation works and a concrete example
To convert a cadastral income into a taxable amount you perform two operations: a 5% uplift to the rendita catastale and then multiplication by the applicable coefficient. For example, if the uplifted rent is €525, applying the IMU coefficient of 160 for residential categories (group A, excluding A/10) produces a taxable base of €84,000. If the same €525 is multiplied by the price-value system coefficient used for a primary residence—115.5—the resulting reference value is €60,637.50. This simple arithmetic highlights how the choice of multiplier changes the taxable base and, consequently, the tax burden or recorded value in administrative acts.
What that example means for owners
The example emphasizes that different fiscal uses produce different outcomes: the IMU-driven figure tends to be higher than the amount used for registration under the price-value approach. Owners and buyers should therefore expect divergence between amounts used to calculate municipal duties and those used in notarial or registry contexts. For planning purposes, it is wise to simulate both paths and to keep documentation showing the declared sale price, because administrative procedures may require the actual transacted figure despite alternative cadastral declarations.
Coefficients by category and special rules
Multipliers vary by cadastral group and by purpose. For IMU purposes the main coefficients include: group A (residential, excluding A/10) 160; A/10 (offices and studios) 80; group B 140; shops C/1 55; and cellars/garages (C/2, C/6, C/7) 160. Under the price-value system for transfers, key multipliers are: first home in group A (except A/10) 115.5 and second home in the same group 126; offices A/10 63; shops C/1 42.84; group B 147. Some types in group D may use lower coefficients (for example 63 for certain categories). Pertinences such as garages or cellars typically follow coefficients aligned with their reference category.
Pertinence, declarations and required evidence
Legal distinctions among cadastral groups matter: group A covers private dwellings, B includes public or collective buildings, C groups commercial units and related pertinences, D covers special structures, and F lists units not used for production. When drafting a deed the parties must still declare the actual sale price, and if works have altered the property or a bonus has been used without updating records, an adjustment may be required. Proper classification and timely updates protect owners from under- or over-declarations and from future compliance actions.
Rights valuation, reform background and what owners should expect
Rights such as usufruct and naked ownership are converted into monetary values using standard tables that account for the usufructuary’s age and the legal rate. The table currently in force for these calculations is the one referenced to 2026, and it is used when allocating values in successions or transfers. Separately, a structural reform of the cadastre is included in the policy document for 2026–2028: it aims to modernize mapping tools, detect unregistered units and integrate property, registry and tax data into a unified owners’ registry to strengthen compliance and make rendite more consistent with market values.
The reform effort has already produced field activities: a reconnaissance phase covered 60 provinces and approximately 65% of the territory, and authorities sent about 3,000 compliance letters—1,800 of which concerned units without a registered rent. The planned improvements seek transparency, periodic adjustment mechanisms and tools for municipalities and the revenue agency to identify unregistered or incorrectly classified units. For owners this could mean more frequent requests to update cadastral entries after public-backed renovations and a closer match between possession and formal registration.
Ultimately, understanding the mechanics—the 5% uplift, the different multipliers, and the distinction between tax purposes and transfer accounting—is essential to manage taxes and legal documents. For precise figures and to handle special cases (for example complex group D units or usufruct valuations), use an up-to-date calculator or consult a qualified professional who can factor in local rules and the ongoing reforms.