Child car seats and airbags: the rules for the theory test
Updated •4 min read
A rear-facing baby seat must not be fitted into a seat protected by an active frontal airbag, because in a crash it can cause serious injury or death to the child (Highway Code rule 101). Gov.uk says you must deactivate front airbags before fitting a rear-facing seat in a front seat.
This page sets out the child seat rules that appear in the Highway Code and on gov.uk, and where the driver's responsibility lies. It is for learners revising for the car theory test, and is not legal advice.
The airbag rule
There are two statements to learn, and they say the same thing from different sides.
- Rule 101 says a rear-facing baby seat must not be fitted into a seat protected by an active frontal airbag.
- Gov.uk says to deactivate any front airbags before fitting a rear-facing baby seat in a front seat (gov.uk: child car seats, the rules).
Gov.uk also says child car seats must not be fitted in side-facing seats.
Height, age and seat belts
Children must normally use a child car seat until they are 12 years old or 135 centimetres tall, whichever comes first (gov.uk). Children over 12, or taller than 135cm, must wear a seat belt.
Rule 100 says a baby seat, child seat, booster seat or booster cushion must be used if a child is under 1.35 metres tall. It must suit the child's weight and be fitted to the manufacturer's instructions.
Rule 100 also puts the duty on the driver. The driver must ensure that all children under 14 wear seat belts or sit in an approved child restraint where required.
Height-based and weight-based seats
Gov.uk describes two ways seats are approved:
- Height-based seats carry an "E" in a circle and an R129 label. They must be rear-facing until the child is over 15 months old.
- Weight-based seats carry an "E" in a circle and an ECE R44 label, and are grouped by weight.
| Weight group | Child weight |
|---|---|
| Group 0 | up to 10kg |
| Group 0+ | up to 13kg |
| Group 1 | 9kg to 18kg |
| Group 2 | 15kg to 25kg |
| Group 3 | 22kg to 36kg |
Only approved seats can be used in the UK, so check the label rather than relying on the age or height alone.
Passengers aged 14 and over
Rule 99 says you must wear a seat belt in cars, vans and other goods vehicles if one is fitted. Adults and children aged 14 and over must use a seat belt or child restraint, where fitted, in minibuses, buses and coaches.
Exemptions exist for medical exemption certificates, and for deliveries or collections under 50 metres in goods vehicles.
How it shows up in the test
Questions on this area tend to turn on one fact: who is responsible, which seat position, or which threshold applies. The responsibility for children under 14 is the driver's. Gov.uk does not publish the questions or say how many are about child restraints.
Our revision guide shows how to fit these rules into a plan, and our Highway Code guide explains how the book relates to the test. You can try the free practice questions to see how the rules are asked.
Check your knowledge
The free theorytest.ai diagnostic shows whether safety and passenger rules are a weak area. theorytest.ai is independent and is not affiliated with the DVSA. Always check the current rules on gov.uk, because seat approvals can change.
Frequently asked questions
Can you put a rear-facing baby seat in the front with an airbag?
Not with an active frontal airbag. Rule 101 forbids it, and gov.uk says to deactivate front airbags before fitting a rear-facing seat in the front.
How long must a child use a car seat?
Until they are 12 years old or 135 centimetres tall, whichever comes first, according to gov.uk.
How long must a height-based seat face backwards?
Gov.uk says height-based seats must be rear-facing until the child is over 15 months old.
Who is responsible for children wearing seat belts?
The driver. Rule 100 says the driver must ensure children under 14 wear seat belts or sit in an approved restraint.
Are child car seats in the theory test?
Child restraints are in the Highway Code, which the questions are based on. Gov.uk does not say how many questions cover them.