My ex-girlfriend and I broke up about 3 years ago now and I have been paying child maintenance to her but I do not think its fair and I’m not sure on how to try to complain about it. We basically share the care of our son 50/50 but this is not agreed in any legal sense, just what we have mutually agreed. Originally she had him 100% of the time for the first few months, before she agreed to share. I have been making the payments to her this whole time, as technically she has a lower take home salary to me, but I recently found out through a mutual friend of ours that she is actually on near enough the same salary as me but she voluntarily contributes a large proportion to her pension. I’ve worked it out on this salary calculator https://www.income-tax.co.uk/ and figured out her salary from the information the friend has given me. I believe she also receives some sort of child tax credits, that I do not. I don’t think its fair that I am sending her money due to her income that she has CHOSEN to have. Our costs for his care are the same, so why am I paying some of her share? How can I go about appealing please?