Do you have to have CSA? If you need it, fine, but if you don't maybe it will be easier if it's not paid rather than have to pay it back. Can Centrelink help at all?

I assume the ATO know he's overdue with his tax returns? Otherwise I'd suggest dobbing him in.
Tashybabe
i had to lodge for CSA, if i didn't, then Family Tax a and b would be cut to the minimum.

ATO, CSA and FAO are already chasing him for late tax returns. (nasty letters).
i don't need to dob him in, because of the above. The approp. gov departments already know he is behind with tax returns.