at age 8 and older or taller than 4'9". All children age 12 and under should ride in the back seat.
Tweens - age 8 and older
When children outgrow their booster seats, (usually at age 8 or when they are 4'9” tall) they can use the adult seat belt in the back seat, if it fits properly (lap belt lays across the upper thighs and the shoulder belt across the chest).