Isofix base confusion

[Fourleafclover93]

I can't find the answers to these questions on Google so hope someone can help on here.

Currently have an ickle bubba stage 0 car seat and isofix base which came with travel system. I will soon need a bigger car seat for DS. Looking at one that is extended rear facing and lasts until he is around 12. Not decided on which brand yet but not ickle bubba.

Will the new car seat fit my isofix base or do I need a new base for different brand/bigger seat?

The ones I'm looking at mentions a top tether can be used. My current isofix base has a support leg so does that mean i don't need to use top tether? Not sure if my car is compatible with top tether or not. I still need to check

Thanks

The next stage seats don't tend to use a base and have the connectors for isofix attached to the shell of the seat.

@dementedpixie thanks

You won't need a base for the next seat. But I would personally not bother with any of the ones that go up to 12. The decent ones are forward facing, so only really suitable for older children. The ones that have a rear facing mode incorporated are a false economy as well as being less practical and less safe than seats which cover just one (max 2) stages.

It's better to get an extended rear facing seat - either a cheap belt fitted one, or an isofix spinning one up to approx 18kg, or a Swedish style one up to 125cm/25kg. Then after this seat is outgrown get a high backed booster seat that only covers that stage. It's much cheaper to do it this way, and you get a better seat covering each stage :)

If you look at seats with top tether then you must check you have the tether anchors in your car. If not then they won't be compatible, as the tether is essential.