When living with/hosting other people (spouse, family members, children, friends etc... both EU/EEA and NON EU) the communication of the property disposal (Cessione di fabbricato or Dichiarazione di ospitalità) must be submitted at the local Questura, by 48 hours after the arrival of the person at home (or after have received the keys of the house):

• Form "Dichiarazione di ospitalità" for Non EU citizen regardless the duration of the stay. It must be done for anyone (including minors).  A copy of the form is required for the permit of stay (family purposes inlcuded).
• Form "Cessione di fabbricato" for Italian, EU, EEA  citizen  for more than 30 days (uninterrupted). 

A form must be filled in and signed by the host along with: 

• Copy of the passport of the host (landlord or tenant) and of each guests; for NON EU guests also copy of the Visa (if requested to enter Italy) and copy of the permit of stay or of the postal receipt 
• Copy of the rent contract (it must be signed). 

Download the form and see how to fill it out. 
Download the forms for Questura in Trieste: 

• Form A for ITALIAN and EU citizens (Cessione di fabbricato)
• Form B for NON EU citizens (Dichiarazione ospitalità). 

Who is the host?

It could be the landlord who rents a flat to a tenant or a tenant who hosts family members, children or friends.