The law on child car seats

You'll want your little one to be as safe as possible when travelling by car.

What are the rules?

Babies, toddlers and children must use a car seat or booster cushion until they're either 12 years old or 135cm tall, whichever comes first (GUK 2015). The seat must be appropriate for your baby's height and weight, and must be EU approved, as indicated by a label showing a capital E in a circle (GUK 2015).

After this, it gets a little bit complicated. This is because there are currently two sets of regulations running in the UK.

Under the existing regulations, car seats are classified by weight, so you know which seat to buy based on how heavy your baby is. But a new EU regulation is changing this, so that eventually all car seats will be classified by height instead. The regulation is also bringing in other rules, such as changing how car seats can be fitted.

For the time being, both regulations are running at the same time, so the rules depend on which type of seat you buy (GUK 2015):

Weight-based car seats

Your baby will need to be in a rear-facing car seat until he weighs more than 9kg (GUK 2015). However, there's no need to move him to a new seat as soon as he reaches this weight. In fact, it's safest for him to stay rear-facing for as long as possible. You only need a new seat when the top of your baby's head is level with the top of the seat.

When your baby reaches 15kg to 25kg, he can use a child booster seat instead of a baby seat. And once he's over 22kg, he can use a booster cushion (GUK 2015).

Height-based car seats

These new seats are known as i-Size seats, and can only be used in cars with Isofix points. If you choose this type of seat, your baby will need to be rear-facing until he's over 15 months (GUK 2015). After that, you can use any i-Size seat that's appropriate for his height.

Whichever type you choose, never put a rear-facing seat in the front of your car if it has an active airbag. Even for forward-facing seats, check that it's safe to use them with your car's airbag before putting them up front.

Find out from your car’s handbook, or the manufacturer, how far the bag inflates, and make sure the car’s seat is as far back from the dashboard as possible. Only put your child in the front if you have no other choice.

Are there any exceptions?

Children under three years can sit with you in the back seat of a taxi if you don't have your car seat with you, provided that the taxi has a fixed partition between the front and back seats. At all other times, or if you're using a taxi that doesn't have a fixed partition, your child will need to be in his car seat, even for short journeys.

Children three and over, who are less than 135cm tall and under 12 years can only travel in the back of a car using an adult seat belt if:

• They are in a taxi with a fixed partition between the front and back seats.
• They are travelling a short distance "in an unexpected necessity". This is to cover emergencies where you might have to collect your child, or someone else's, at short notice, and don't have the right car seat with you.
• You need to carry three children but can only fit two car seats in the back of the car. In this case the third, and preferably tallest, child should use an adult seat belt.
• Some classic cars don't have any seat belts fitted. If you are travelling in this type of car, children age three and over are allowed to travel in the back unrestrained. However, just because it is legal, doesn't make it safe.

What's wrong with children using adult seat belts?

If your child uses an adult seat belt before he is tall enough, the lap part of the belt sits too high on his stomach. In a crash this could damage his internal organs. There is also a risk of him slipping under the belt.

I need to buy a new child seat. What should I look for?

Child restraints are designed for specific weight ranges of child, so weigh your child before you buy.

There are different categories of car seats suitable for different age ranges. Those that meet European safety regulations will have an E and 44.03/44.04 or .03/.04 on the label, meaning they meet European safety regulations. They'll also show the group number, or weight range of child, for which it is designed. The new i-Size seats are slightly different, as explained below.

Weight ranges may vary from one manufacturer to another, but they tend to follow these guidelines:

• Group 0 and Group 0+: rear-facing infant carriers for children up to 10kg and up to 13kg respectively (from birth to nine or 12 months).
• Group 1: child seats for children 9kg to 18kg (about nine months to four years).
• Group 2 and 3: booster seats and cushions for children from 15kg to 25kg (about three and half years to six years) and from 22kg and up to 36kg (about six years to 12 years). Many models in these groups can be modified to accommodate your child as he grows.

What's different about i-Size car seats?

i-Size is a new European standard for car seats. It came into effect in July 2013, with the aim of making buying a car seat simpler and safer (Which? 2014). It means that car seats will have to pass more tests in order to be sold (Which? 2014). Changes made by this regulation are going to be gradually phased into the UK until around 2018.

i-Size seats are fitted into a car using the Isofix system, which will reduce the risk of car seats not being fitted properly. Most cars made from 2007 onwards are fitted with an Isofix system, so fitting a car seat should be simple and easy for everyone (i-Size nd). The new regulation is also striving to make car seats that fit in all cars.

Another important change is that i-Size car seats will be based on your child's height, rather than her weight. This should make it easier for you to tell if your child is in the right-sized car seat.

The i-Size regulation is being introduced gradually, so there aren't many i-Size car seats available yet. For this reason, you don't need to worry about replacing your car seat with a new i-Size seat yet. The old car seat regulations (R44/04) will run alongside the new i-Size regulation until around 2018, but i-Size will eventually replace it (i-Size nd).

What are the penalties for breaking the law?

If your case goes to court, you could be fined up to £500. Find out more at www.gov.uk.

See our guide to buying a Group 1 car seat.