I think that if it does work out that he has overpaid then it just means he wont need to pay for a while until its all sorted. So i think you can safely spend the money that you have, and any over or under payments will be sorted between CSA and X. Just bear in mind that maybe in the future you may not receive any payments until its all evened out, but i dont think they will make you give any money back to anyone. I do see where your coming from that the money its been based on and what he is spending isnt his income, and i agree that that will come into account. Maybe just call CSA agency and ask a as a general inquiry what happens if your partner over pays. I am sure they will help you out!!