You should always use the address where your car is going to be parked for most of the year. In the case of students, this will be at their university and not at their parents’ home.  Don’t be tempted to use the latter (unless you live at home while attending university) as it could result in any claim you make being rejected and your policy voided.  This is because your premium is based on the area where your car is located most of the time, which may be considered a higher risk compared to where your parents live.