As of 2014, if the car contains a front passenger air bag, a child can ride in the front seat if he is no longer using a rearward-facing car seat. These seats are used until a child is 9 to 15 months old or weighs 22 to 29 pounds.
All children must use the proper child car seat or restraint, depending upon their age and weight. Rearward-facing baby car seats should be used from birth through at least an age of 9 months old or a weight of 22 pounds. There are some seats that are rear-facing that fit children up to 15 months old or weighing 29 pounds. Once a child is in a forward-facing car seat, he can ride in the front seat in the U.K.