Booster cushion for tall 3 year old?

[Kittle]

Hello, I don't think I've ever posted on here before but I'd really appreciate some advice!

My ds will be 3 yrs 7 months next month when we'll need to take him in a taxi. He is very tall, the height of some 5 year olds. So I'm wondering whether he's tall and heavy enough to sit on a booster cushion rather than the high-sided booster seat that we generally use now.

Has anyone used a booster cushion (i.e. one of the small cushions that are recommended for 4 yrs plus) with their tall 3 year old? If so, would you advise trying it?

We could take the bigger booster seat, which would be more awkward to carry but of course if it's safer I don't care about that.

Thank you very much in advance :-)

I think it is done by weight limit.

From memory the child must be 18kg for a simple booster seat.

The combined booster/high-backed seats are suitable from 15kg.

Hope that helps.

Booster cushion alone is not recommended before 22kg. Much safer to use a high back until then but not actually illegal to just use a cushion from 15kg