Rules presented here apply to both those who are in Italy for WORK or STUDY purposes.

In 1997 Italy joined the Schengen System which implied a removal of internal border controls, giving total freedom of movement within all the territories of the Schengen agreement signatory member states.
The Schengen Area comprises the national territories of the countries that already applied the Convention: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Italy, Luxembourg, The Netherlands, Portugal, Spain, Sweden, Iceland, Norway, Slovenia, Estonia, Latvia, Lithuania, Poland, Czech Republic, Slovakia, Hungary and Malta.
According to the law decree D. Lgs. nr. 30, dated February 6th 2007 regarding the "Application of the Directive 2004/38/CE about the right of EU citizens and their relatives to freely circulate and stay in Member States” starting from April 11th 2007, EU citizens and Non-foreigners are allowed to move without restriction throughout Italy and without applying either for the visa or the stay permit upon arrival.

Your entry

Non-foreigners are those Nationals of all the European Union, the Schengen States and the European Economic Area member countries (Austria, Belgium, Bulgaria, Cyprus, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lichtenstein, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom) who benefit from the same visa exempt status.

Your stay

Short stay (less than 90 days) - During the first 3 months of your stay in Italy, no particular requirements have to be fulfilled, apart from holding a passport or other identity documents valid for expatriation.

Long stay (more than 90 days) - Any EU/Non-foreigner citizen has the right to stay in Italy more than 90 days if:

• s/he is an employee working in a position of subordination to and under the direction of another person (Article 2094 of the Civil Code), under a contract of employment;
• s/he is a self–employee performing work activities under an independent contract, under which one party undertakes, for a fee, to perform a task or service without the ties of subordinate status and using predominantly his or her own labour;
• s/he is in possession both of sufficient income/means of support for the whole duration of the stay and of a valid health insurance policy covering all expenses in case of emergency treatment in Italy.

After 90 days of uninterrupted stay in Italy, the applicant has to register at the Municipality of the city where s/he lives (Comune - "Ufficio Anagrafe"), by providing some proof of employment or financial resources, which can be in the form of bank statements, tax returns or a contract.
For further details, please check the following link at CINFORMI.

The registration will automatically imply the change of residence from the home Country to Italy and the necessary fiscal consequences.