Child support

Quick question about child support.

My eldest is off to Uni so I’m now paying for three kids instead of four. When i check the calculator for the new payments I probably naively thought this would drop roughly 25% a month but in fact has only dropped 9%.

wages etc haven’t changed much at all since i checked last year. In fact when i add the eldest (doesn’t ask for age just added a 4th) to the calculation to add a 4th kid i get roughly the same monthly cost as 3

Does this sound right enough?

Isn’t the calculation something like X for the first kid, .6X for the second and .2X per kid after that? Might explain it

That might but it doesn’t explain how the calculator says id be paying less for 4 kids than I would for 3.

I’m tired but i cant see how this works