How to fit an ISOFIX Base or ISOFIX Car Seat

ISOFIX car seats are among the safest ones for your little one to travel in. Whether you bought an ISOFIX base for your baby car seat or a toddler or child seat that has ISOFIX connectors, it is important to install correctly in order for the car seat to be safe.  

What does ISOFIX look like on a car seat? 

All of our ISOFIX bases and ISOFIX car seats have two fixing points (yellow metal bars) to attach to the vehicle seat. Our ISOFIX bases have an additional support leg, to provide extra stability in case of a collision. Our ISOFIX car seats for toddlers either have an additional support leg or top tether for extra stability. 

Because we care for your little one’s safety, we have created an installation checklist with safety tips for you as parent to feel confident that your little one’s car seat is installed correctly.  

Before you buy (if you have not done so yet) 

Safety tip 1. Consider the installation method that best fits your car and your lifestyle. ISOFIX car seats are attached onto your car’s ISOFIX fixing points, whereas belted car seats are installed with the seat belt of your car. Discover all pros and cons of ISOFIX vs. seat belt installation, to find out which installation method fits you better.  

Safety tip 2. Also, make sure that your car has ISOFIX. The best way to do so, is to check the user manual of your car. Most new cars will have ISOFIX, but in some cars it is not possible to install a support leg or top tether. Our helpful Car Fitting List will tell you exactly which of our Maxi-Cosi car seats fit your car.

How to fit an ISOFIX base or car seat 

For your little one’s safety it is crucial to install our ISOFIX base or ISOFIX car seat properly. Follow the below 3 steps, to make sure your little one will travel safely:  

1. Pull out the ISOFIX fixing points of our base or car seat. These are the yellow metal bars.  
2. Place the base or car seat on the back seat of your car.  
3. Push the car seat firmly against the back rest to lock the 2 fixing points onto the metal clips of the vehicle seat. You will hear a “click” when this has been done properly.  

For your peace of mind, our ISOFIX bases and car seats have a colour indicator to confirm a correct fit. This way, you can rest assured that your little one is safely installed in the car at all times. 

How to fit an ISOFIX base or car seat - Legs and tethers  

Did you know that ISOFIX bases and ISOFIX toddler seats have a third fixing point? They either have a support leg or top tether that needs to be installed as well.  

Support legs and top tethers are designed to prevent the base or car seat from moving forward in case of a crash. Only ISOFIX child seats are safely secured with the 2 fixing points only.  

Installation of support leg*:  
1. Pull it down, adjust it to the right height and position it on the floor of the car.  
2. Make sure the leg is stable against the floor when you lock it firmly in position. 

Installation of top tether:  
1. Clip the yellow hook onto the ISOFIX fixing point on the boot floor of your car.  
2. Make sure to firmly tighten the tether. 

Just like the two ISOFIX fixings on the vehicle seat, our bases and car seats have colour indicators to confirm when the support leg or top tether is correctly installed. 


*If you use a support leg, for your little one’s safety it is important to check whether the floor of the car has a floor storage compartment. If so, double-check the user manual of our car seat to find out how to install the support leg in combination with the compartment.