To change the date and time of the booking of your tickets with seat allocation** you must use the Booking Code (PNR) and the Booking Change Code (CP), which are printed on the tickets (see example, italian only) or which will have been sent via email when buying.

In summary:
1. The new booking must relate to a trip to be made from the moment of purchase and up to two months after departure of the originally booked train.

2. Booking changes are allowed free of charge:

For tickets ticketless, the same procedure applies but booking changes are made only with the ticketless procedure: for requests made on-line, a confirmation e-mail is sent or booking change confirmation is given by the ticket office operator or by the Call Center, or the details of the new booking are displayed on the screen of self-service machines if used.
If a booking is changed online or through the Call Center, on request of the customer, the confirmation can be given also by a text message to your mobile.

PLEASE NOTE
Booking changes online, through the self-service machines or requested by telephone to the Call Center or one's travel agency is only allowed if tickets are issued for one or more trains of the same category (e.g. for the journey, only one ticket was issued for WL from Rome to Trieste or a ticket was issued with two bookings for an ES* service from Turin to Milan and from Milan to Ancona).

If you are a customer registered with the Trenitalia web site, you can make the booking change online (operating every day 24 hours) until the booked train's departure by typing these following codes into the fields below: