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What are the UK's car seat laws?

  • Parkers outlines the current child car seat laws in the UK
  • Should your baby have a height- or weight-based seat?
  • Latest child seat and car booster seat laws covered

Written by Graham King Published: 11 August 2022 Updated: 13 September 2023

Child or baby seats aren’t just a luxury for parents to keep their backseat riders comfortable – they’re a legal requirement. Until a child is 12 years old or meets the minimum height for an adult seat, by law they must be seated in a proper, protective chair while travelling in a car.

However, some of the finer details of child seat laws can be confusing. There are rules on which car seats to use, how many can be installed and how to properly secure them. And that’s before you get to the rules governing all the different types of child seats. From boosters to 360 degree child seats, it’s worth carefully considering which will be right for you.

In this guide, we’re going to break down what the UK’s laws on child seats say and how you can stay on the right side of them. Need a seat? Check out our picks of the best toddler car seats.

What are the rules for child car seats in the UK?

UK law says that children must be secured into a safety car seat until they’re 12 years old or 135 centimetres tall – whichever comes first. You can find all of the official guidance on the government website, or keep reading here.

What are the UK’s car booster seat laws?

From 1 March 2017, the UK hasn’t approved new backless booster seats for use by children under 125cm tall or less than 22kg in weight. Looked at from the other end, it’s only children over 125cm tall or 22kg in weight who can safely use a backless car seat. However, if you have a booster seat that was manufactured before 1 March 2017 date, the restrictions don’t apply.

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Child thumbs up in car seat
Good quality child seats will keep your children safe.

Height-based child seats vs. weight-based child seats

The height vs. weight question is rooted in changes to the regulations surrounding car seats. They previously revolved around weight as the child’s changing physical characteristic. The current laws use height as the changing characteristic, but since weight-based seats are still cleared for use, the two sets of standards run concurrently. And the debate about which is more relevant persists.

Height-based child seats are known as i-Size. Such seats must have a label showing a capital E in a circle and the code R129, which indicates that they’re approved for use by the EU, therefore they’re legal in the UK.

EU-approved weight-based child seats are also labelled with the circled E logo and the code ECE R44.

Whether height- of weight-based seats are best is a matter of personal opinion – it’s best to try both to find out which works best for you and your child. By selecting a seat designed for the specific height or weight of your child, they will have best possible protection in the event of a collision.

Should UK car seats be forward-facing or rear-facing?

Children up to 15 months of age or 9kg in weight (whichever comes first) must face the rear of the vehicle. Rear-facing child seats help protect the head, neck and spine in the event of a collision.

You can switch to a front-facing child seat once your child is over 9kg in weight or older than 15 months. The seat must be the appropriate height for the child – if their eyeline is above the top of the headrest, the seat isn’t suitable for them. Incidentally, many parents choose to keep using rear-facing child seats for toddlers, because they do still provide better crash protection.

When can babies face forward in a car seat?

Children can face forward in a car seat from the age of 15 months, or when they reach 9kg in weight. At that point, they’re strong enough that their head, neck and spine don’t need the extra crash protection facing the rear provides. However, it’s still not ideal for safety, so many parents choose to keep older children in rear-facing seats.

What’s the difference between ISOfix, Cabriofit, ISOfit and IsoSAFE?

Isofix is the international standard for child seat installation and it ensures your child is secure in the car after every fitting. The Isofix system consists of mounting points attached to the car’s structure and clasps on the seat, both a standardised design so any seat can be used in any car.

Isofit child seats use standard Isofix mounting points to install the seat in the car, but you then use the car’s seat belt to secure the child, rather than an integrated five-point harness. The latter can support a child weighing up to 18kg, beyond that the car’s belts are safer. Therefore Isofit seats can only be used by older children.

Many older cars don’t have Isofix mounting points and that’s where Cabriofit child seats come in. Such seats have Isofix clasps on the base, but they can be retracted out of the way for use in cars that don’t have matching mounts.

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Very young baby asleep in baby car seat
Car seats are available for children of all ages.

Isosafe is a protocol for keeping a child seat stable in the car and is unrelated to the installation of the seat, or the mechanism that keeps the child secure. Brands such as Joie state that their seats are Isosafe compliant.

We’ve noted in our vehicle testing that not all Isofix mounting points are created equal in that the distance between the mounts and the seat cushions varies from car to car. We therefore advise that you do a trial installation of any child seat you’re thinking about getting in your car before you commit to buying it. Likewise, always test your child seat in any car you’re thinking about buying.

Can you put car seats in the front seat?

In most cars, there’s a choice of three or four seats in which a child seat can be installed – front passenger seat, right and left rear seats, sometimes the middle rear seat if it’s wide enough. Note that Isofix mounting points are usually only found on the outer rear seats, though some cars do have them on others including a number of MPVs.

According to safety experts, the back seats are the safest place to put a child seat. However, some parents may still wish to have their child in the front – it’s easier to keep an eye on them when no-one else is in the car, especially if the child is in a rear-facing seat.

It is legal to install a child seat in the front of a car, but you must turn off the front passenger airbag. Pretty much every car made in the 21st Century has some means of doing so. Consult your car’s owner’s manual if it’s not obvious how to do so.

What are the UK laws for carrying children in classic cars without seat belts?

Rear seat belts weren’t legally required on new cars in the UK until 1983. Children over three years old can be carried in the back of such classic cars without being fastened in. However, if you regularly have children in a pre-1983 car, maybe one that was named Parkers Car of The Year way back when, we recommend having rear seat belts installed. There are many specialists who offer a range of solutions, including retrofitting Isofix mounting points in suitable cars.

Is it illegal for children to travel in vehicles without car seats in the UK?

Generally speaking, yes it is. But there are some exceptions to that rule. Child seats aren’t legally required in taxis, coaches, buses or minibuses, but kids over three years old must wear an adult seat belt if one is provided.

You can also get away without using a child seat in a car if the journey is unexpected, necessary and short. For instance, your car may have broken down and you’re getting a taxi to a train station to continue the journey. Again, child over three years old should wear an adult seat belt in the back of the car.

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Girl on ipad in car seat
Keep your child comfortable for a relaxing journey.

These rules are a little complex and it’s easy to get caught out. If your car breaks down and the recovery truck driver offers a lift to a train station, you would only be able to take the offer if his vehicle is a crew cab with back seats. If not, you’ll have to get a taxi.

Our advice is to always use a child seat in any road-going vehicle if it’s at all possible, especially when the journey is long and your child is under three years old. They’ll be much more comfortable and you won’t have to hold them.

What if there’s no room for a child seat in the back of the car?

If your car’s back seat to too small to install a child seat, or it isn’t wide enough for all the child seats you need, children must be carried in an appropriate seat in the front of the car. If you car’s back seat isn’t wide enough for three child seats, there is a potential solution available from Multimac.

The brand’s bench-type child seats offer three or four individual seats, each with a full five-point harness, and fit in the back of many larger family cars.

When does a child not need a car seat?

Children no longer need to travel in a child seat when they reach 12 years of age, or 135cm in height, whichever comes first.