Finally on-sale in Australia, ISOFIX car seats are easier to install correctly than child seats relying on seatbelts alone. Here’s how to install an ISOFIX child car seat.

AUSTRALIAN PARENTS had been waiting for ISOFIX child car seats for years, excited by the notion of being able to fit their child’s car seat quickly, easily and securely each and every time. Then, late last year, the Australian Design Rules were changed making it legal to buy and fit ISOFIX child car seats. But, there was a … but to all of that.

The change to the rules doesn’t mean you can simply hop online and order an ISOFIX car seat from overseas. Nope, the seat still has to meet the specific Australian Design Rules and, so far, only Maxi-Cosi and Britax have released product meeting the required standards. Maxi-Cosi hit the market first with Britax (which released an ISOFIX car seat co-designed with Holden) following shortly afterwards.

We’ve been testing the Maxi-Cosi and will feature a review of it shortly, but the aim of this article is to explain how to install a forward-facing ISOFIX child car seat. It’s not necessarily as straightforward as you might think. How to install an isofix car seat ISOFIX mounts. The first thing to do is locate the ISOFIX mounting points which are usually down at the bottom of the seat where the seat back meets the seat base. If your car has ISOFIX mounting points you’ll see them easily enough as they’re usually labelled with the word ISOFIX. We’re used a Subaru XV to install the seat and its mounting points are hidden behind two little flaps; one on each side of the seat (see picture). The XV is able to take two ISOFIX child car seats, some cars, like the Commodore, have three ISOFIX mounting points across the back seat. How to install an isofix car seat ISOFIX seatbelts. On either side of your ISOFIX child car seat you’ll find a belt with a latch. Locate your child seat so that you can access the ISOFIX mounting point and then take one of the ISOFIX belts and latch it onto the car seat proper. You’ll here the ISOFIX seatbelt click when its locked. Then reach over and attach the other side. How to install an isofix car seat How to install an isofix car seat Green is good. Once you’ve latched the two ISOFIX seatbelts into place you’ll notice an indicator on the belt that will show a red band. Grab the strap and tighten the seatbelt until the indicator band shows green. Then repeat the process on the other side. It took me about five minutes of mucking around to get both indicators to go green (they kept showing a slither of red) and I ended up having to put my entire body weight onto the seat to tighten the ISOFIX belts to get a solid green band. How to install an isofix car seat   How to install an isofix car seat Top tether. Taking the top tether strap, latch it onto its mounting point which can either be up on the roof of the car, on the back of the rear seat or up on the parcel shelf, depending on your vehicle. After you’ve latched the top tether strap double-check that there’s no slack and that the indicator on the ISOFIX belts are green.


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  1. Nice review! In the UK, the ISOFIX is sufficient to secure the seat and no additional tether strap is required. I find the difference in laws between countries interesting and would like to know what testing has been undertaken to confirm that ISOFIX alone is not sufficient without the additional tether strap.

        1. That can be good or bad. A top tether will hold the seat more securely and acts as an independent restraint. However, in a crash you want energy absorption. So having the seat move forwards (pivoting on the mount points) is not necessarily bad. It means the seat back is there to help with whiplash. The same concept is seen with active head restraints, and even seatbelts have some elasticity. Child seats do too, which is one reason they aren’t to be re-used after a major crash. So I don’t necessarily agree that making a seat fitting super-tight is a good idea, and that’s also the same reason manufacturers say the top tether should have the slack taken out, but stop short of saying “tighten”.

  2. The seat is tested with one or the other installation style… Isofix OR seat belt install. PLEASE TAKE THAT LITTLE BIT OF INFO OUT BEFORE YOU HURT SOMEONE WITH YOUR “EXTRA SAFE TACTIC” Car seat Manufactures do not recommend BOTH at once!!!!

    Also. The top tether strap should not be tight! It should have the slack taken out only!!!!!! This is very important for the restraint to be able to work properly!

      1. Thank you Isaac, There is a really great face book page called “Child restraints. Is your child restrained correctly?” You should join and continue to do more articles on car safety.

        Members on there will be happy to help you with it 🙂

  3. Hi Isaac- great article. The car seat manual states that isofix is not to be used in conjunction with the seatbelt. It is one or the other. Hopefully you can correct this 🙂

  4. You twat. Did you read the manual.
    You must be the2% who still stuff up isofix.
    Its either isofix or seat belt. Using both is less safe as it puts extra stress on the seat. The teather when rear facing sjould just have the slack taken out. Not super tight.
    Please read the manual you just told parents to put their child in danger by installing wrong.

    1. The article has been amended. I didn’t discuss the fitting of a rear-facing child seat and nor did I see it should be super tight, just that it should be as tight as possible; to me that’s the same as saying there shouldn’t be any slack. – Isaac

      1. Thanks FingerDiddle, but I can’t condone the language or statement. I made a mistake and wrote the wrong thing in the article but have now corrected it after some of the comments here and further research. I never intended to mislead parents and am grateful for all of the comments, good or bad on any article that Practical Motoring publishes. And, we’re not too big to admit when we’ve written the wrong thing. – Isaac

  5. Infasecure also have an ISOFIX seat on the market. Please do a bit more research when writing car restraint articles. A motoring writer does not make you an expert on car restraint safety. A lot of people could potentially follow your bad advice, and there is already a lot of ignorance and bare minimum attitude to safety out there. You have such a great platform, it would be great to have some well informed and well researched articles regarding best practice for car safety out there! PS Spelling error on ‘here it click’

    1. Hi C, thanks for your thoughts. I never said I was an expert in car restraint safety, but I do have small children and have spent plenty of time fitting different types of car seats to different types of cars. Now, before I get howled down, I don’t believe that makes me an expert. Yes, I suggested you should use both a seatbelt and the isofix latches, and this was wrong. This has now been corrected. My suggestion to pull the top tether tight could also have been misconstrued, so I have corrected the article to state that slack should be removed.
      My aim with the article was really just to show potential ISOFIX seat buyers how they should fit the seat… you’ll notice none of the pictures show a seatbelt in use, so, I believe the photos are still relevant and useful and now that the article has been amended, hopefully it will be seen as helpful. – Isaac

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