Car seats and boosters provide critical protection for infants and children in the event of a car crash. In California, children are not permitted to ride in the front seat of a passenger vehicle until they are at least eight years of age.To answer the question "when can a child sit in the front seat", all children aged eight years and younger must ride in the back seat in CA. California Vehicle Code 27360 states that children under the age of 2 must ride in a rearfacing car seat. Schedule an Appointment: call 408.848.2324. Families that meet the income requirements and complete the class will receive a free car seat. Clinic in the Park's Boosters in a Bag. Children under the age of 8 must be in a car seat or booster seat in the back. It is best for children to ride in a seat with a harness as long as possible, at least to 4 years of age. Children who are at least 60 pounds and at least 6 years of age (up to 15) can be sufficiently restrained in a vehicle safety belt.