The «Gli immobili in Italia 2026» report puts municipalities' remaining IMU headroom at €1.1 billion, 7% of receipts. With rates close to the maximum, the tax now grows through cadastral income, starting with 20,000 compliance letters by year-end.
«Gli immobili in Italia 2026», the report published by the Finance Department of the Ministry of Economy and the Property Market Observatory of the Revenue Agency, opens with the headline figures: €6,088 billion of residential wealth, 67.4 million registered units with a cadastral income, 75.8% of households owning the home they live in. For owners of income-producing property the useful chapter is a different one, on the new IMU rate template.
It says that municipalities have almost run out of room.
Little headroom left on rates
Since 2025 councils have had to set IMU rates through a standard template, which makes the choices of nearly eight thousand authorities comparable for the first time. 7,314 municipalities, 98.9% of those examined, adopted it. 57.5% apply a single rate, the rest differentiate by category. The remaining headroom for higher revenue is estimated at about €1.1 billion, 7% of actual IMU receipts.
Most councils are therefore already close to the 10.6 per mille ceiling, or 11.4 where the old TASI surcharge applied. Property taxation as a whole yields about €42 billion a year, 7.7% of total tax revenue.
Collection and the tax base
With rates capped, two routes remain: collect what is already due, or widen the base. The report uses machine learning to estimate IMU and TARI collection efficiency and finds room for improvement without touching rates. The second route is already under way.
By year-end the Revenue Agency plans to send around 20,000 compliance letters to owners of buildings that exist on the ground but not in the cadastre, or appear there in a version overtaken by extensions, changes of use or new construction. The anomalies come from comparing cadastral maps with aerial imagery. Press accounts differ on the scope: some focus on properties renovated with tax bonuses since 2019 and never re-rated, others on buildings missing from the register altogether. Some sources report that around 70,000 properties have already been updated voluntarily.
Cadastre and planning are separate
The letter is not a tax assessment. It asks the owner to check and, if the omission is confirmed, to file a Docfa update, possibly with reduced penalties.
What is often missed is that updating the cadastral income regularises nothing in planning terms. An unauthorised extension recorded in the cadastre is still unauthorised, now with a certain date and a document describing it. Cadastral conformity declared in the deed and planning conformity are separate checks, and aerial monitoring makes it more likely that discrepancies surface after completion, at the new owner's expense. In fragmented portfolios, holiday homes and rural complexes, plans, actual condition and building permits should be compared during due diligence.
The bill for non-residential assets
Main residences outside the luxury categories are exempt, so IMU falls on second homes, let properties, shops, offices, warehouses and building land. The report counts more than 6.5 million let units and about 6.6 million held at the owner's disposal.
Under current rules the risk of rate increases is limited, and IMU can be modelled as a stable cost relative to cadastral income. That income, however, has become the moving variable. Every update reflecting a renovation, every building that surfaces, every revised classification raises the tax without any council vote.
Developers face one more check. Buildings built for sale have been exempt since 2022 while unsold and unlet, provided the formal requirements, including the declaration, are met. On unsold stock inherited from stalled schemes this cannot be taken for granted.
A tax that grows from below
A general revision of cadastral values has been discussed repeatedly over the past decade without being completed, and its political cost makes it unlikely soon. The report shows that routine maintenance of the cadastre achieves a similar effect on a smaller scale, without public debate. Tax risk on property is moving from the council resolution to the individual cadastral record.