My oldest turned five in feb and is still I. A harnessed booster. She will remain in the harness till she outgrows it . She'll hit the height limit before wait . I think we have at least another year . Current youngest is still rear facing at 16 months . He will be rear facing till the limit of his seat . Pretty much every child around my oldest age is in high back or no back boosters already . It makes my hear plumet everytime I see it .