British Law requires both parents to contribute, if the children are resident in the UK and both parents are resident in the UK then the calculations of support for the children are worked out based on who has custody of the children and on a proportionate basis of the earnings of both parents.
Saying that the system is vastly unfair and causes great pain to all concerned.
My personal knowledge of this? Well I have a lovely 24 year old daughter and one way or another we managed to avoid the Child Support Agency for 19 years. We did both contribute my ex partner (a Scottish lassie) worked sometimes and I gave everything I could whether Shona was working or not, it was not easy for either of us but our reward is our grown up daughter Gemma who has made us both proud.
I hope I do as well for my new Filipino daughter Gemma's little sister who is only 3 years old just now
Not the first time I have posted this picture hereI am very proud of my daughter!