Do I need proof of identity?

The Swiss Transfer Ticket is only valid with your Identity Card or Passport, which must be shown with the ticket if you are subject to an inspection.

How is my age determined?

Your age is determined on the first date of travel, regardless if you have a birthday during your trip (eg if you are aged 15 at time of departure, you can have a child’s ticket, even if you turn 16 before your return).