I've just completed my tax return, providing all the necessary information from my P60, P11D etc. I have a private pension on which I claim standard tax relieve, and that's it. I have 3 children (16, 13 and 13), and the calculation for the child benefit received is £2,636.00. Can anyone explain to me why, when I complete my tax return the repayment figure is returned as owing £2,738.60 or £102.60 more than I've received in child benefit. I earn over 60K a year meaning I should payback 100% (or £2636 only), but HMRC have decided that I somehow owe an extra 1.26% . I do not owe anything from previous years and I'm PAYE. So where has this additional child tax come from?