Car Seat Expert Answers Your Questions On Car Seat Laws, iSize & More

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When do I need to use a car seat

All children must use a child car seat until they’re 12 years old or 135cm tall, whichever comes first. There are exceptions to this car seat law in extreme circumstances, for example, in the case of children over three, only if it’s an emergency or unexpected journey and only over a short distance. Although the child still has to sit in the back of the car, with an adult seatbelt. Always best to be on the safe side for your child’s safety and to avoid serious injury & fines.

Why does my child need a car seat?

A properly fitting car seat can be life-saving in the event of a collision as they ensure your child is securely fitted to the seat of the car, much like how a seat belt does for someone who fits the seat of the car properly.

What type of car seat is right for my child?

With so many car seats on the market, it can be difficult to decide on the best one for your child. Ultimately, as long as you’re choosing one that is safe for the height and weight of your child and with good safety credentials, you shouldn’t go wrong, after that it comes down to preference. It’s important to take into consideration what you’re going to be using the car seat for. For example, if you know you’re going to be lifting your baby in and out of the car, it’s probably better to go for a lightweight infant carrier with a base that stays in place.

Should I be choosing a car seat based on weight or height?

This can be confusing as there are currently two sets of regulations running parallel. The newer regulation, known as R129, or iSize (explained further below) states that car seats should be fitted by height. Any new ISOFIX car seats introduced to the market after 2018 will be fitted this way. The older regulation, R44, fits car seats by weight. Belted seats are still only available in R44 form. Existing car seats that met the first regulation are still safe and legal to use so both are feasible. For ease if you’re a new parent go with height as this will become standard.

Are the rules the same in cars and vans?


What about taxis?

Most good taxi companies will provide a car seat, if prior notice is given when booking.  However if an appropriate car seat isn’t available a child over three can travel in the rear of the taxi, wearing an adult seat belt. It is illegal for a child under three to travel without a car seat or restraint in the front or rear of a taxi and it is the driver’s responsibility to ensure the child is correctly restrained.

What are the penalties for ignoring the law on using car seats?

The driver is singularly responsible for the safety of everyone in the car, and the penalty for offenders is a £100 fixed penalty notice.

How do I fit a child’s car seat safely? 

As obvious as it sounds, make sure to always read the manual. All car seats should come with fitting instructions so be sure to follow them to the letter, preferably alongside the fitting instructions in your car’s instruction manual. If you are still unsure, the majority of car seat stockists will have a designated person on hand who’s trained to fit car seats properly. It’s always best to check if you’re not sure!

Is it safe to buy a second hand car seat?

In a word, no. Tempting though it may be, you can never be completely sure of the history of a car seat. If it’s been in a car crash, even a minor one, its safety has been compromised.

Do they expire? 

Car seats do not have a set expiration dates and there are no legal requirements that determine their maximum usage. However, manufacturers will recommend a ‘service life’ a bit like a ‘best before’ date, these will vary across different car seat models. It’s best to check each car seat for the manufacturer recommendation.

Is it ok to use the car seat if it’s been in a collision?

The official advice says that even in the case of a mild collision, a car seat can be left weakened meaning it won’t offer the same level of protection in the event of another accident, even if there’s no visible damage. We would always advise against using a car seat after it’s been in a collision.

Are the rules different for children with disabilities?

The rules are exactly the same for children with disabilities or medical conditions although they can use a specialist seat or restraint designed to fit their needs. If your child can’t use a restraint or seat belt because of their condition, a doctor can issue an exemption certificate.

If I have three kids all in car seats, is it safe to have them all in the back at the same time?

It is safe, as long as all three car seats fit securely; in some smaller cars it won’t be possible to have three car seats in the back as there simply won’t be enough room. Children under three must be in a child car seat. If there’s no room for a third child car seat in the back of the vehicle, this child must travel in the front seat with the correct child car seat.


What is iSize?

‘iSize/R129’ is the new safety regulation brought in by the EU in July 2013 to make child car seats easier to fit, provide better protection, and keep children rearward facing for as long as possible. It uses the child’s height to work out the right fit rather than weight and includes a side-impact test to ensure that the seats provide better protection from side impact collisions. All iSize car seats are rearward facing for children up to 15 months which is safer too.

Will Britain leaving the EU impact iSize?

No change will occur to the standards used in the UK, the R129 standard is adopted by many countries outside of the EU anyway, as its pass criteria is very strict.

What is ISOFIX?

Isofix is a child car seat attachment system built into your car. It uses metal anchor points (or metal bars basically) that are set into the seats of your car to make the fitting of car seats easier and therefore safer. This system works with both ISOFIX & iSize car seats. But, it’s important to note that non iSize car seats are still safe and meet the safety regulations set by R44.

If my car seat isn’t iSize do I need to buy a new seat?

No, as long as your car seat fits with current safety regulations (R44), is the right size and is in good condition there’s no need to buy an iSize approved car seat. When buying your next seat do consider it though as they will have been tested under the latest safety standards – always reassuring.

Why is rear facing better?

Before your baby reaches 15 months their neck isn’t developed enough to handle the impact of a collision. This means any involvement in a crash can lead to serious neck injuries. Rearward-facing seats have been proven to be five times safer than forward-facing seats as they hold the head and distribute the force of the impact, avoiding your baby’s head being thrown forward, causing neck injuries, in the event of a crash. We recommend keeping your little one rear facing until they are 15 months.

Why is it better to measure car seat suitability by height rather than age or weight?

Parents use height guides buying clothing but rarely know the exact weight of an older child, so potential misuse is reduced by using height. Children grow at such different rates, so although age and weight can still be considered when working out the right fit, length is the best way of telling whether a seat fits well. It also makes it a lot easier to tell when it’s time to move up in car seat size. iSize has been designed to make this process as simple and safe as possible. But do remember that car seats regulated under R44, which fits by weight, are still absolutely safe to use.

How can I tell if a car seat is iSize?

Handily, they all have a specially designed logo on them. This looks like a child in a car seat with a lower case ‘I’ next to it. (Image below.) Many of the car seat models also have the letter ‘i’ in their name or include the word iSize. But, if you’re unsure, your car seat retailer will always be able to confirm this for you.

Can I have an iSize / Isofix in any car?

No. Although many newer models of car have been designed to accommodate iSize car seats (they have Isofix points installed in the car), it’s still important to check the car seat you want to buy will fit in your car safely. I-Size has been implemented to be a “plug and play” system, so no fitting list is required for using an i-size seat in an i-size certified car seating position. You can check this with the car seat retailer or with the car seat manufacturer’s fitting lists which can generally be found on the retailer/manufacturers’ website.

What ages/heights does iSize cover?

The first phase of iSize only regulates car seats for children up to 105 cm, which is roughly the height of an average 4 year old. Phase 2 for iSize car seats has just been introduced for older children. Children from 100cm upwards can now find seats based on height criteria. Most “Booster seats” are still the R44 type based on weight, best to look for a high back booster seat, rather than a basic backless booster cushion.

Can I still use my current forward facing car seat if my child is less than 15 months old?

Yes, current R44 law states that you can put your child in a forward facing car seat once they are over 9kg (approx. 9 months). The new iSize (R129) law has updated this law to regulate by height and now states that a child should be rearwards facing until at least 76cm (approx. 15 months old). 

The two regulations will run side-by-side for a good few years yet so don’t worry, when the law changes to only allow iSize seats to be sold, you’ll still be able to use your existing car seat, you just won’t be able to buy any old-style car seats from new. So you can still use your current car seat until you’re ready to change.

Booster Seats 

The booster seat laws changed recently – what are they now? 

Car seat manufacturers are no longer allowed to make new backless booster seats for children shorter than 125cm (4ft1) or weighing less than 22kg (3 stone, 6.5 pounds). Children’s measurements vary enormously but as a general guide, this is approximately the size of a six year old. This does not mean no backless booster seats will be available in shops for children of this height – just that car seat companies cannot design and make new backless booster seats for children less than 125cm tall or lighter than 22kg. Manufacturers will still be able to make new backless booster seats for children taller than 125cm or heavier than 22kg.

What is a high-backed booster seat and why are they considered safer for children below a certain height? 

A high-based booster seat is a booster seat with a back support that comes up past the child’s head height. Under new regulations (R129), high-backed booster seats are required for any child shorter than 125 cm or weighting less than 22kg. This is because they offer side impact protection & help to secure the child properly in the seat and help the car seatbelt to fit properly across the child’s body and provide the best protection should a crash occur.

Are backless booster seats unsafe for my child?

Backless boosters are still, for the moment, certified as safe and legal. The new law is designed to gradually phase out the existing recommendation of using a backless booster seats for children 15kg or over. But any backless booster seats already on the market for those 15kg or over are still legal and safe to use. 

I would always recommend that parents make the change over to a high-backed booster when possible, and for as long as possible. Even beyond the legal minimum height requirement of 125cm. In fact, I’d advise any parent to keep their child in some form of booster seat until they are naturally tall enough for the seat belt to fit snugly on the shoulder and hips and therefore take the force of an impact. On average this means keeping your child in a booster seat (backless or high-backed) until 150cm or 12 years old. While this may be tricky they really do provide better protection for your child in the event of a crash.

How does the car seat law change affect me?

The law change only affects you when buying a booster seat that came to the market after 9th February 2017. In this instance, if your child is heavier than 22kg or taller than 125 cm then you can buy a backless booster seat, if you child is less than 22kg or shorter than 125cm then you will need to buy a high-backed booster seat. 

It could get a little confusing for everyone as retailers will still be stocking and selling backless booster seats brought to market before the 9th February 2017 law change. This means that backless booster seats will still be in circulation, listed as suitable for children over 15kg despite the revised regulations of 22kg. Ideally, we feel responsible retailers should be changing their stock over to the newly certified booster cushions as soon as they become available. For this reason, Joie does not make or sell any backless boosters.

Can I still use my backless booster seat even though my child is smaller than these new regulations?

Yes you can still use it legally, as long as the booster seat complies with current regulations. However, the new law is designed to increase the safety of your child so I would always recommend high-backed boosters as the best option because of the improved fit of the car seatbelt across your child body.

Car seats for infants

What is an infant car seat?

An infant car seat is generally known as an “infant carrier” one that is rearward facing and is used specifically for littles ones from birth up to 15 months old (approx. 13kg).

Why are infant car seats safer for this age group?

Rearward facing car seats are the safest options for this age group, as before your baby reaches 15 months their neck isn’t developed enough to handle the impact of a collision. This means any forwards facing use too early can lead to serious neck injuries in a crash. Rearward-facing seats have been proven to be five times safer than forward-facing seats, as they hold the head and spread the impact, avoiding your baby’s head being thrown forward in the event of a crash and extreme forces on the neck.

How long should I use an infant car seat for?

Generally your little one will need an infant car seat until they are about 15 months or weigh up to 13kg. However, there are an increasing number of car seats on the market that grow with your child, and enables you to use the car seat until they are much older. It’s incredibly important to make sure that you don’t keep a child in a car seat that they’ve outgrown as the seat will no longer protect them and can actually end up doing more harm than good in the event of a crash.

Are carrycots okay?

No, regular carry cots are designed for carrying your baby when out and about and therefore aren’t a valid replacement for a properly fitting car seat. The good news though is that there is an increasing number of lightweight lie-flat car seats that can be removed from the car and easily used like a carry cot.

Why does the incline of the car seat matter for a new-born?

Essentially, if the incline is too steep for a new-born, the weight of the head will allow them to nod forwards when asleep and not keep the baby in position. If too reclined then in the event of a crash, the impact will be transferred to the baby’s shoulders and neck instead of the car seat bearing the brunt of it which is obviously incredibly dangerous. Likewise the advice nowadays is to limit the time your new-born spends in a car seat. Research funded by The Lullaby Trust shows that new-born babies are at risk of breathing difficulties if left sitting upright (40°) in car seats for over 30 minutes, particularly when travelling in a car. Latest lie-flat infant carriers can help with this if traveling regularly for long journeys.

Additional tips

What are car seat harness clips and should I be using them?

Car seat harness chest clips are designed to make it harder for children to slip the car seat harness off their shoulders. However, as most clips are not permitted under EU regulation, we would advise against using them as you may end up compromising the safety of the car seat.

Why shouldn’t my child wear a winter coat when strapped into a car seat?

The added bulk means that if the child is propelled forward in a crash, the car seat harness will be too loose to be properly effective. It’s a much better idea for the child to be without a coat in the car seat but wrapped up in blankets to keep warm. This has the added benefit that the child can regulate their own temperature too by removing one of the blankets if they get overheated.

Remember to fasten you booster seat back in with the seat belt, if not restrained by ISOFIX, as the seat is only secure when the child is within and the belt attached. Many adults forget to restrain their booster seats when little one isn’t in the car. A loose booster seat can be the most dangerous object in the car when loose……think of it as having the weight of a baby elephant when in a 30mph collision…….fasten it in when you drop them off at school etc.

(maybe even make it little ones job to keep you safe as they get out, they fasten the seat belt back into place, keeping you safe and saving you the job).

About the Author: 

Damon Marriott is the Head of Product Development, Joie UK

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