I am in the mix at the moment and if she were to go to Centrelink, they would send her to CSA. CSA cannot do an assessment past 3 months or 9 months in very exceptional circumstances. She would have to file with the courts for an order for CSA to go back beyond the 3 months and if they did find that she was owed $xyz then it is then up to the father to pay it - but CSA cannot enforce the payment if it was private collect at that time and additionally, Centrelink would look at her payments and if she received any payments during that time (Fam tax for example) she would be deemed overpaid and would have a Centrelink debt regardless if the father paid or not. Further more, for her to enforce the payment if CSA find that he owes (this is after she has got an order from the court), she would then have to file with the courts to get an enforcement order of some kind. So it wouldn't be worth her while.