Booster seat/extended harnessed seat or correctly fitted seatbelt
When your child turns 7, they’re not necessarily ready to move out of their booster and into an adult seatbelt.
The law says the adult seatbelt must fit them correctly. If it doesn’t, they’ll need to stay in an approved booster or child restraint until it does. Seatbelt fit varies from car to car and even from position to position in the same car, but most kids aren’t big enough to fit properly into an adult seatbelt until they’re about 10 to 12 years of age (approximately 145cm).
There’s a pretty important safety reason for this – vehicle seats and seatbelts are designed for adult bodies so it’s highly unlikely your child will fit an adult seatbelt when they reach their 7th birthday. A child that moves into an adult seatbelt too early is twice as likely to suffer devastating injuries in a crash.
So persevere, keep your children in the back seat in a correctly fitted booster until it is safe to move.