The tax identification number (codice fiscale) is a code to identify citizens in their dealings with the Italian Public Administration. Every Italian citizen is issued with one by default at birth, but also foreigners residing in Italy are required to have one, for example to obtain a residence permit, open a bank account, register for the National Health Service, rent an apartment, request a telephone line, etc.
EU/EEA citizens must show a valid passport or equivalent ID; non-EU / EEA citizens must have a valid passport with appropriate visa (if required) as well as a photocopy of the passport (of the pages clearly showing personal data and visa) and/or residence permit. Alternatively, the tax identification number can be requested before arrival to Italy from the Italian diplomatic authorities in the country of residence.
Foreign citizens entering Italy with a research visa will receive a certificate of attribution of the tax number at the time of the convocation to the Immigration Desk (Sportello Unico per l'Immigrazione - SUI).