Cantpay
you seem to be under some miscomprehension.
You say you paid the £450 happily, which would be what CSA said, plus more. Thats good of you.
If you were out of work you could have paid less. Your agreement was such that it wasnt court ordered I think, just an agreement. Even had it been CSA calculated you could have asked for an adjustment according to your income at the time.
Yes, your ex would have jhad less, but if you were not earning she wouldnt really have been able to complain. No-one would be calculating the shortfall and making you pay in the future, thats plain wrong.
The only time you would have to pay in the future is if you didnt tell them of a change of circuymstances, and it became arrears. Even then you could appeal and given the evidence, got your arrears reduced.
But similarly if your income increases then your contribution increases. Not index linked, but at the % calculated as reasonable, because, as others said, you are the child's father and frankly 15% is peanuts considering how much of your wages would go towards supporting a child if you were still married. Wouldnt even cover nursery if you were both working, never mind food, clothing, activities, holidays, etc. You still get 85%.
And it is exactly because you are a single man, not having to deal with the responsibility of having a child live with you, that you have been able to concentrate on building your career and getting to the position you are in now
I think, and you clearly state, that what you actually object to is being told what to do by an outside agency. You deliberately set up a ltd company so your 'wages' are minimal. Shame on you.