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UK car seat laws: make sure your child’s booster seat is legal

Choosing the right car seat protects your child in the event of an accident. But if you are caught with an unsuitable or incorrectly fitted booster seat, you could be hit with a £500 fine. Read our guide on how to buckle up safely.

Woman looking at car seats

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What is the law on child car seats?

In the UK, a child must use a car seat until the age of 12 years old or 135cm tall, whichever comes first. Children taller than 135cm or over the age of 12 are required to wear a seatbelt, like an adult.

If your child does require a car seat, you can select which seat is appropriate based on their height or weight (more about car seat categories below).

Always ensure that the seat you are buying is EU-approved for use in the UK – just look for a label with a capital “E” in a circle.

In addition to the “E”, the label on approved height-based seats should show “R129” and on approved weight-based seats should show “ECE R44”.

Only an EU-approved car seat can be used in the UK.

What are the penalties for breaking the law?

Drivers currently face a fine of up to £500 and three penalty points for using the wrong child restraint.

What do car seat groups mean?

Car seat groups are based on weight ranges and may overlap one or more of the seat categories.

The car seat group numbers are:

  • Group 0: 0-10kg (approximately birth to 6-9 months)

  • Group 0+: 0-13kg (approximately birth to 12-15 months)

  • Group 1: 9-18 kg (approximately 9 months to 4 years)

  • Group 2: 15-25 kg (approximately 4-6 years)

  • Group 3: 22-36 kg (approximately 6-11 years)

When can my child sit in the front seat with a booster seat?

Children aged between three and 12, or up to the height of 135cm (4’4”) in the UK and 150cm in Ireland (4’9”), can travel in the front passenger seat of a vehicle, provided that they are secured in a booster seat.

Once a child exceeds a height of 135cm (4’4”), they may travel without a booster seat in the front of the car.

However, it is illegal to have the passenger airbag switched on when a child in a rear facing car seat is in the front seat as the airbag could cause serious injury in the event of an accident.

For children in a forward-facing seat, the passenger seat should be pushed back as far as possible so that the airbag will not make an impact and injure the child.

However, safety experts agree that the safest place for a child is the middle rear seat (so long as it has a 3-point seatbelt). This is furthest away from the sides of the car and is less likely to be hit during impact.

What’s more, the back seats are generally considered safer as there are fewer distractions for the driver while on the road.

There are some exceptions when a child over the age of three does not need to legally use a car seat:

  • In a taxi or minicab, but they must wear a seatbelt and travel in the rear. Children under three should travel in a taxi or minicab without a seat belt for safety reasons as it can cause injury in a crash.

  • For journeys in a coach or minibus where a suitable car seat is not available, but they must use a seat belt. If there is no adult seat belt fitted, children must travel in the rear seats of the minibus or coach.

  • Children over the age of three are also legally allowed to use an adult seat belt in a private car if making an unexpected but necessary journey over a short distance.

Does my child need a rear-facing car seat?

All babies must be rear facing until they are 15 months old, as before this their necks are not strong enough to withstand the pressure of a head-on collision in the forward-facing position. Groups 0 and 0+ are rear facing.

Are there special car seat rules for babies?

Many infant car seats come as part of a wider travel system and can be clicked into the pram chassis with adapters. But professional advice remains that car seats are for travelling and not for prolonged naps – babies should be sleeping in a flat position wherever possible.

According to the Lullaby Trust, babies should not be in a car seat for longer than two hours at a time and they should be taken out frequently.

How long can I leave my baby in a child car seat?

If you will be travelling for a lengthy period of time, it is advised that you stop for regular breaks to allow you to check on your baby and change their position.

The Lullaby Trust charity recommends that ideally, a second adult should travel in the back of the car with your baby, or if you are travelling alone it is helpful to secure a mirror to enable you to observe your child.

If at any time your baby slumps forward, the Lullaby Trust recommends that you immediately stop and adjust their position.

When can my child use a forward-facing car seat?

Once your child has outgrown their rear-facing car seat, the next step is a Group 1 forward-facing seat with a five-point harness. This should last until the age of four – or around 18 kg. 

The harness can be adjusted as your child grows and the side impact wings provide extra protection for your child’s head and body during impact.

Should I consider a combination car seat to save money?

Combination seats, also known as extended or multi-group seats, can be adjusted as your child grows and cover more than one group, for example – group 1, 2 and 3 seats, which are suitable from 9-36kg – or from nine months to 12 years. 

While the initial cost may be higher, thanks to the flexibility of height-adjustable straps and multiple reclining positions, a combination car seat can prove a good investment over the long term.

However, with this option, you are still required to adhere to the safety guidelines for the weight of your child at any one time.

Isofix vs i-Size - what’s the difference?

i-Size is a new European standard for child car seats that forms part of regulation R129 (basically the height-based seats approval system mentioned above). 

The idea behind i-Size is that children will be seated in an appropriately-sized seat based on their height, outgrowing it only when they exceed the maximum height listed on the label.

i-Size is currently running alongside the old regulations but many new cars are now “i-Size ready”, so it’s worth checking if you have the option to go down the i-Size route when buying a new car.

I-Size seats are only compatible with cars that have Isofix, which is a safety system that uses fixed anchor points to secure the car seat in place, rather than seatbelts.

The idea is that this will be considerably safer as it reduces human error when fitting because attaches the seat to the car with a reassuring click.

You can buy some car seats that come with built-in Isofix connectors while others require the use of an Isofix base to be installed in your car.

How much do car seats cost?

The amount you spend on a car seat will vary, with rear-facing and forward-facing options costing anywhere between £50 and £350.

The good news? Car seats can last for years – meaning they can be reused for siblings - and become less expensive as your child gets older. However, keep in mind that plastic can get brittle with age and car seats have an expiry date. 

When do car seats expire?

Each manufacturer will have a recommended ‘service life’ date for individual products – which are a bit like a ‘best before’ date. This varies across different car seat models and brands.

If you can’t find an expiry date sticker, a good rule of thumb is to avoid anything that could be more than five years old.

Should I buy a second-hand car seat?

While you may be able to bag a bargain by buying a used car seat, be careful. 

The Royal Society for the Prevention of Accidents recommends that you avoid second-hand car seats altogether as you can never be confident that it hasn’t been involved in an accident, even when buying from those you trust.

While you may not be intentionally misled, minor damage can be forgotten or overlooked but still affect the safety of the car seat. 

What if my car seat is stolen or damaged?

If you are in an accident or have had your car seat stolen from your vehicle, you might be able to make a claim on an insurance policy.

However, this type of cover is not always included with a car insurance policy – figures from Defaqto show that nearly a quarter of comprehensive car insurance policies wouldn’t pay out for a replacement.

What's more, those that do pay out in the event of a claim don't offer the same level of cover across the board, with only half of insurers offering a full reimbursement.

If you have more than one car on a multi-car policy or if you take out temporary car insurance to drive a friend’s car, make sure you remember to transfer the car seat to the whichever car you are driving.

What should I look for to ensure my car seat is properly installed? 

If the seatbelt or harness is loose, twisted or appears to sit incorrectly across your child, make sure that you correct the placement before you head off.

During winter months, be mindful to remove your child’s bulky coat before adjusting the slack as the thickness of the material can leave the harness too loose to be effective in an accident.

Alternatively, place your child into the car seat without their jacket and buckle them up tightly. Then, simply pop the coat on 'the wrong way around' by sliding it over the arms and laying it over their upper body.

This will still protect your little one from the cold, without compromising the safety of the harness.

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