Ex and I split up 15 years ago, I've been paying the same amount (£332 a month) since 2001 for my daughter who's now 17. In the meantime, I've had two other children but not notified the CSA, largely because I was worried that my ex would start kicking off about contact (like she did for about 5 years after we split up) if her payments were reduced. I've now been told by the CSA that I owe them £700 (nothing compared to some of the horror stories on here, but it's still £700) in arrears due to an error at their end in 2003. I'm challenging the arrears, but it doesn't look as if I'll get anywhere with that judging from what I've read here. I don't care what the ex thinks if 'her' payments are reduced now, as my daughter is perfectly capable of travelling to see me whenever she wants to. If it looks like I'm going to end up having to pay the arrears, is it worthwhile notifying the CSA of my change in circumstances to offset the repayments? Or might they decide I owe more arrears? I'm obviously earning more money than I was in 2003, and have been for some years.