Change of use

Article 23-ter of the code defines as significant in planning terms a change assigning the property or the unit to a different functional category among those the article itself sets out. Moving between functional categories is therefore the decisive test.

Paragraph	Functional category
a)	Residential
a-bis)	Tourist and hospitality
b)	Productive and office
c)	Retail
d)	Rural

The test is therefore functional rather than material: the planning significance of a change of use depends not on the works but on the move between categories. An office turned into a dwelling moves from the productive and office category to the residential one, and the change is significant even where no work at all is carried out.

The resulting distinction is between a vertical change, crossing categories, and a horizontal change, remaining within the same category. The applicable rules differ in each case.

Decree Law 69 of 2024, converted by Law 105 of 2024, clarified a point that had generated uncertainty. It concerns the definition of a change without works.

A change of use is treated as being without works not only where no building work is carried out, but also where any works needed fall within the works of article 6 of the code, meaning permit free activity. The category therefore extends beyond the literal case.

The notion of absence of works is therefore not to be read in a purely material sense. It is a clarification appreciably widening the field of change without works, because it allows the minimal adaptations that ordinarily accompany a change of use to be brought within it.

On this aspect the 2024 amendment introduced a simplification with a minimum consent. The consent required is lighter than under the previous regime.

For a horizontal change, within the same functional category, the rules distinguish change without works, for which a certified notice is required, from change requiring works, for which the consent proper to the works to be carried out is needed. The distinction determines which consent applies.

The same simplifying principle applies to vertical changes of individual units, between different functional categories, even where carried out without works or through permit free activity: in those cases a certified notice is always required. The perimeter remains bounded by the homogeneous zones identified.

The operational rule practice has distilled from this is that the certified notice is the minimum consent for a change of use. Where the works needed would fall within certified notification, the notice applies nonetheless; where the works require a permesso di costruire, the permit is needed.

One point of coordination should be held firmly. Where the change of use sits within a wider project, it is not absorbed by the building work but constitutes a functional component to be assessed expressly. Case law has repeatedly held that where the works significantly affect the building organism, a change of use cannot be handled through simplified consents.

Here lies the most important limit of the whole regime, and omitting it is the main cause of refused applications. Omitting it is the main cause of applications being refused.

A change of use must take place in compliance with the municipal planning rules. The simplifications introduced in 2024 operate within that perimeter and do not override it.

Administrative case law has further clarified that article 23-ter does not automatically prevail over planning agreements in force: unilateral modifications are not permitted and compliance with the original obligations remains paramount. Planning agreements must therefore be checked upstream.

The code also expressly preserves different provision by regional statutes and municipal planning instruments for changes within the same functional category of a whole property. Checking the local framework precedes any assessment.

The correct checking sequence therefore has three steps, in order: the functional category of origin and of destination, the compatibility of the change with the planning instrument and with any agreements, and the applicable consent. Reversing the second and third steps is the most frequent error.

One point of delimitation should be known because it bounds the territorial scope of the changes. Outside that perimeter the earlier regime continues to apply.

The simplifications introduced in 2024 on changes between functional categories operate by reference to the homogeneous zones the rules identify, and it is within that perimeter that a vertical change of individual units is permitted on the conditions provided. Their scope is therefore territorially circumscribed.

Outside that perimeter, and where municipal planning instruments or regional statutes provide otherwise, the assessment reverts to the ordinary rules. The assessment reverts to the local framework.

Checking which homogeneous zone the property falls within is therefore a preliminary step and not a detail of context. It should be carried out on the planning instrument in force, which is also where one checks whether the municipality has introduced provisions of its own.

The guidance and interpretative criteria issued by the Ministry of Infrastructure and Transport provide clarification on these aspects, and consulting them together with the text in force is advisable before setting up a conversion project. They do not, however, have the binding force of legislation.

For changes permitted under the provisions introduced in 2024, the rules disapply the obligation to provide further land for services of general interest and the requirement of a minimum parking provision. That disapplication has a bounded scope.

This is a simplification of concrete weight, because providing standards and parking was in many cases the decisive economic obstacle to conversion projects, particularly in consolidated urban fabric where available land does not exist. Providing standards and parking was in many cases the decisive economic obstacle.

The scope of that disapplication is however bounded by the provisions granting it, and should be checked case by case rather than assumed as a general rule. It must be checked case by case.

A change towards a more onerous functional category triggers payment of the difference in development contribution. The balance must be calculated before the application is filed.

The mechanism is economically significant and frequently discovered late. Municipal tables attribute different infrastructure charge incidences to the functional categories, and moving from a category with a lower incidence to one with a higher incidence generates a balancing payment.

The check should be carried out at the start of the feasibility assessment, by consulting the tables of the competent municipality, and not at the end. On conversion projects covering large floor areas the balancing payment can be the item determining whether the project is viable.

Assuming that without works means without consent is the first, and ignores that planning significance depends on the move between categories and not on the works. Planning significance turns on the category, not on the works.

Checking the consent before checking planning compatibility is the second, and produces formally correct applications for changes the planning instrument does not permit. It produces formally correct applications for changes that are not permitted.

Overlooking planning agreements in force is the third, and case law has held that the national rules do not automatically override them. Case law has held that national rules do not automatically override them.

Treating the change of use as absorbed by a wider building project is the fourth, and omits the express assessment of the functional component. The change component must be assessed expressly.

Omitting the check on the contribution balance is the fifth, and is the one with the greatest financial impact. It is the one with the greatest financial impact.