@gfwantsmoney I'm not going to put in figures because the minute you do that you go down a rabbit hole of comparisons and what things should or shouldn't cost and what is or is not necessary. In general terms though, I don't include in my calculations of cost my mortgage or utilities as ex has those too, but factoring in food at home and school, uniforms, sports kit, clothes and shoes for school and home, bus fare, activity fees (one sport each, one set of music lessons total), phone bills (modest, like £10pm each), entertainment eg trips out once a month or so, pocket money - teaching money management so they get some on a card every month, laptop for school use etc, the maintenance I get covers 1/4. It was significantly less of a % when I was also paying for childcare over and above what was covered by tax credits. I earn a decent wage so only ever got the childcare element and not WTC.
Of course there is no one size fits all and it will never be fair while they try to operate a system like that. But as a pp said, there is zero political will to address this properly and fund a system that would be fair to ALL parties. I don't think high earners should be capped - why would you NOT want your children to benefit from your wealth, especially if they are with the other parent most of the time - I'm not sure many people would see it as good parenting if 26/30 days the kids were in cramped and pretty average settings with no hobbies or outings but get taken on some amazing holiday once a year by a disney dad. I get that "fear" that the money isn't spent on the kids but that's another well worn trope isn't it? An RP who dares to ring fence some of their own money for their own use is "spending the maintenance on gin" or whatever. My ex thought this and was disabused at mediation. He thought that so long as he topped up the "gap" between my total earnings and the household cost that was enough. The mediator had to explain to him that I was entitled to some of my wages for my own use, not that it should ALL be swallowed up by the household.
What I do know, is that if I ring fenced 18% of my salary and ONLY used that for the kids, they'd run out of everything long before the end of the month and I would have a fuck load more money to spend on myself than I currently do. And the joke of all that is that he is actually paying the CMS amount. I'm not even arguing from the position so many are in where they receive little or nothing, but its still not right. And I am 100% sure there are NRPs or partners of them on here who could absolutely legitimately complain that they are getting the shitty end of the stick. The one thing we mostly agree on is that the system is buggered and does not work for pretty much anyone.