The best way to see how much child maintenance is payable is to go onto the government website and input your details into the calculator ( https://www.gov.uk/calculate-your-child-maintenance). If you do not know the paying party’s income you can ask the Child Maintenance Service (CMS) to carry out a calculation. They will have access to HMRC records.
You then need to agree the amount payable with your former partner and if that is not possible ask the CMS to deal with payment (additional fees will have to be paid). The calculation is based on the paying parent’s gross income less pension contributions and there is a reduction depending upon the number of nights the children stay overnight.
Child maintenance payments usually stop when a child reaches 16 (or 20 if they’re in full time education up to A-level or equivalent).
The court can only deal with child maintenance in limited circumstances, for example, if the paying party’s income exceeds the CMS limit or the child is living abroad.
The court can make orders in relation to the payment of school fees and associated expenses.
School fees can be paid from a parent’s income or a capital fund may be available. Please bear in mind that payment of school fees is not on the top of the list when it comes to looking at the needs of the family as a whole.