There are multiple options for living in Milan. Bocconi has 6 different residences dedicated for students. From what I experienced, there are only 3 available for international students, Residence Bocconi, Arcobaleno, and Spadolini. However, Arcobaleno is the only international residence and the others require a late housing application and then you are given the option for the other residences. In addition, there is an option for finding an apartment, which is generally cheaper.
For housing through the university, I recommend paying everything up front or as early as possible if that's what you decide to do. You can start in the dorms and then move out if you'd like. The bill comes at the end of every month and the window to pay without a late fee is very small only one to two days.
According to Bocconi's Website, there are 2 ways to pay your rent:
1- You may pay the amount indicated on the your bill directly to a bank in Italy; Bocconi suggests that you pay it at Banca Popolare di Sondrio located at Via Bocconi 8, Milano which is the Bocconi bank (right next to Residence Bocconi): Mon-Fri from 8:30am to 1:30pm and from 2:45pm to 3:45pm. You may pay it at the bank by cash just showing the bill you received.
2- You may pay the amount indicated online by credit card at http://www.scrignopagofacile.it: as a non-registered user. You can make payment using the "payments" function by inputting the codes from the payment notice received. In addition you need to indicate: name, address, post code, town, province, amount to be paid, due date and a description of what is being paid. All this information is available on the bill; NO TAX CODE (codice fiscale) is required. These details are necessary for generating a receipt for the payment. The website indicated is in the Italian language therefore you have to choose the 3rd box on the right called “UTENTE ANONIMO” and then click the button “ENTRA”. You will then have to click on “Pagamento con avviso (predeterminato)” and then on “M.Av. Elettronico” putting the code of the notice of payment in the box called “codice identificativo”.
The online payment system is very unreliable. You can go into the housing office and talk to them about it and they will tell your there is something wrong with your credit card. This is not the case, it is their system. That's why I recommend paying up front if you can and are willing to commit. For more questions e-mail Laura Matera at housing.isd@unibocconi.it.