Those who move house, rent an apartment or leave a property will have to pay more attention to the calendar. In fact, with the local tax reform one of the most important deadlines of the TARI changes: the declaration relating to the beginning of the occupation of a property or subsequent changes must be presented within 90 days.
The innovation is contained in Legislative Decree 147 of 2026, published in the Official Journal. The provision rewrites various rules on local taxes, from the IMU to the waste tax, but it is precisely on the TARI that the effects can be most immediate for families, tenants and owners who directly use a property.
Tari, what must be communicated within 90 days
The rule is quite simple. From the moment the possession or detention of premises or areas subject to the Tari begins, there are 90 days to submit the declaration to the Municipality or the waste service manager. The same term applies when changes subsequently occur that modify what has been declared.
The most common case is that of a move. Anyone who buys a house and starts using it, anyone who moves into a rented apartment or, on the contrary, leaves a home must therefore promptly update their position. The same can apply to changes in the surface area used, the use of the premises or the number of occupants when this data affects the tariff and is not automatically acquired by the Municipality.
It is better to talk about occupants and not simply members of the family unit: the forms required by the Arera regulation in fact consider both people resident and those domiciled in the property. The concrete methods through which to communicate the changes remain those provided for by your municipality or by the manager.
What changes compared to before
Until the reform, the reference tax deadline for the Tari declaration was, according to the interpretation provided by the Ministry of Economy, 30 June of the following year, unless different deadlines were established by the Municipalities. With the new rules, however, a mobile deadline is introduced directly into national law: June of the following year no longer counts, but 90 days must be counted from the event that gives rise to or modifies the obligation.
For many taxpayers this will not be completely new. The Authority, which also regulates the waste sector, had already introduced the 90-day deadline in 2023 and several Municipalities had already adapted their procedures. But with decree 147 the term now ends directly within the national regulations of the TARI, making the term much clearer also on a tax level.
In other words, those who until now waited until the following year to settle their position should no longer do so: the deadline to keep in mind is the three-month deadline.
There is also a discount for those who compost
The decree contains another innovation that can affect the waste bill. A reduction in the rate must be applied to families who carry out individual aerobic composting of their organic kitchen waste, cuttings and garden prunings. A similar measure is envisaged for some non-domestic users in the agricultural and nursery sectors. However, the law does not establish a single national percentage: to concretely know the extent and methods of the discount it will be necessary to refer to the regulations applied locally.
The sanctions for those who do not submit the declarations correctly will also change. However, the new percentages will only come into effect for violations committed from 1 January 2027: the penalty for failure to declare will be equal to 100 percent of the unpaid tax, while that for an unfaithful declaration will be 40 percent, in both cases with a minimum of 50 euros.
What also changes for the IMU
The reform affects the IMU at the same time. The declaration is directed towards an exclusively online system, with a national model that will have to be regulated by the Ministry of Economy. The deadline of 30 June of the following year remains and a generalized annual obligation is not introduced: a declaration already submitted continues to be valid until there are changes that affect the tax. While waiting for the new ministerial decree, the models already provided for by the legislation remain usable.
The news on the disputed cadastral income is more limited. When the Revenue Agency rectifies an income and the owner challenges it, any final accounts with the Municipality can be made much later. Once the process is concluded, the entity will have until December 31st of the fifth year following the finalization to recover any higher IMU, applying only the legal interest. Within the same deadline the taxpayer will be able to request the refund of the amount paid in excess; the Municipality must make the reimbursement within 180 days of the request.