Centrelink payments going into a bank account cannot be directly garnisheed. Although, the amount that does not fall under the ‘saved amount" can be garnisheed. The ‘saved amount" is your Centrelink payments for the four weeks before the garnishee order was made minus anything you have withdrawn from the account in that four weeks.
Whatever, centrelink payments are not spent in the four weeks is the amount that can be garnished. In other words, if the recipient of the centre link payment spends all of their centrelink payments within the four week period, there is no amount that can be garnisheed.