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Fastening systems such as ISOFIX, Top Tether and LATCH ensure greater child safety in the car. Learn how to use each one correctly
Child safety in cars is one of the issues that most concerns parents and guardians. With the increase in the number of vehicles on the streets and the importance of protecting children on any journey, correctly securing the child seat in the car makes all the difference in the event of an accident. And it is in this context that terms such as ISOFIX, Top Tether and LATCH emerge — systems developed precisely to facilitate the safe and standardized attachment of child seats.
But what is ISOFIX? How does it differ from other systems? And what is the correct way to use it? In this article, we will explain everything you need to know about the main child restraint systems, how they work, which cars are required to have them, and the most common installation errors.
What is ISOFIX?
ISOFIX is an internationally standardized child seat attachment system that aims to ensure greater safety and ease of installation. The name comes from “International Standards Organization FIX“, that is, an ISO standard that fixes the child seat directly to the car’s structure.
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Unlike the traditional seat belt, the ISOFIX secures the child seat using rigid metal hooks connected directly to the vehicle chassis, without relying on belts. This significantly reduces the risk of installation errors, increasing the child safety in the event of a collision.
How the ISOFIX system works in practice
- The vehicle must have two fixed metal hooks at the base of the rear seat.
- The ISOFIX compatible child seat has two arms with locks that fit into these hooks.
- The system issues a click when the installation is done correctly.
- Some models include visual indicators (green/red) to confirm the fit.
- The attachment is made directly and rigidly, without the use of the car's seat belt.
In addition to the two main hooks, most modern vehicles also have a third anchor point called Top Tether, which reinforces security.
Top Tether: what is it and what is it for?
The Top Tether is a third anchor point that works as an “additional belt” attached to the top back of the car seat. It is anchored to a hook located behind the seatback (it may be on the floor, backrest or trunk, depending on the car).
The main function of Top Tether is:
- Prevent the child seat from moving forward in frontal collisions.
- Reduce the risk of neck and head injuries in children.
This system complements ISOFIX and is mandatory in many countries — including Brazil, in models manufactured from 2018 onwards.
What is the LATCH system? Is it the same as ISOFIX?
The LATCH (Lower Anchors and Tethers for Children) system is the American equivalent of ISOFIX. It works with the same goal: to provide an easier and safer way to secure a child seat in the car.
The difference is in some Technical details:
- No ISOFIX, the hooks are fixed to the car seat and the seat has rigid arms for fitting.
- No LATCH, The car seat has straps with clips, which attach to the car's hooks (instead of rigid metal arms).
In Brazil, the ISOFIX system is the officially adopted standard. However, some imported or compatible child seats may also support LATCH, which does not prevent their use — as long as they are installed correctly.
Which cars have ISOFIX in Brazil?
Since January 2018, Brazilian legislation requires that all new vehicles sold in the country leave the factory with ISOFIX and Top Tether anchor points for at least two rear seats.
That is:
- Cars released after 2018 must have ISOFIX and Top Tether.
- Older models may not have this feature.
- You can check whether the vehicle has ISOFIX by consulting the owner's manual or observing the presence of icons with baby chair in the back seats.
How do I know if my car seat is compatible with ISOFIX or Top Tether?
A child seat needs to be certified and compatible with the ISOFIX system to fit correctly on the car's hooks. Some child seats offer:
- ISOFIX attachment with Top Tether (most common and safest).
- Fixation with ISOFIX and seat belt (In some cases, Top Tether may be optional).
- Fixation only with seat belt (for cars without ISOFIX).
A Inmetro certification label must be present on every child seat sold in Brazil, and it generally indicates the type of compatible attachment.
What are the risks of attaching the car seat incorrectly?
According to vehicle safety studies, more than 50% of child seats are installed incorrectly, which completely compromises its effectiveness. Among the most common errors are:
- Not locking ISOFIX correctly
- Forgetting to attach the Top Tether (when required)
- Use loose child seats, just resting on the bench
- Using a poorly positioned or loose seat belt
These errors increase the risk of serious injuries in collisions or sudden braking. Therefore, it is essential to follow the instructions in the manual for the child seat and the car, as well as to test the seat after installation.
Child safety in the car: what does the law say?
In Brazil, the use of child seats is mandatory depending on the child's age and weightaccording to Brazilian Traffic Code (CTB):
- Baby seat: from 0 to 1 year (or up to 13 kg)
- Car seat: from 1 to 4 years (or between 9 kg and 18 kg)
- Booster seat: from 4 to 7,5 years (or up to 1,45 m tall)
- Car seat belt: from 7,5 years old, if you are taller than 1,45 m
The fine for those who do not use the equipment correctly is R$ 293,47 and 7 points on your license, in addition to putting the child's life at risk.
Frequently asked questions about ISOFIX, Top Tether and child seats
▶ What is ISOFIX and what are its advantages?
It is a system that attaches the child seat directly to the car's structure, without relying on seat belts. It reduces the risk of incorrect installation.
▶ Does every car have ISOFIX?
No. Only those manufactured from 2018 onwards are required by law to have the system.
▶ Can I use a car seat with ISOFIX in a car without ISOFIX?
Yes, as long as the car seat also has the option of being attached with a seat belt. Read the manufacturer's manual.
▶ What is Top Tether?
It is an extra strap that attaches the top of the car seat to the car, increasing stability and safety.
▶ What is the difference between ISOFIX and LATCH?
Both have the same purpose. ISOFIX uses metal arms; LATCH uses straps with clips.
Child safety in the car starts with correctly securing the car seat
Knowing how to properly secure a car seat is essential to protect children in the event of an accident. Using the ISOFIX system with Top Tether or, in some cases, LATCH, offers a safe, reliable and easy-to-install method — especially when compared to traditional seat belts.
Child safety in the car depends on the correct use of the right equipment, at the right age, in the right car. And this includes understanding what ISOFIX is, checking that your vehicle is compatible and not putting off installation until later.
