The microsimulation approach combined with reweighting contrasts with a popular method of examining population ageing, which combines population projections with age-specific per capita expenditures on a range of benefits in order to obtain projected social expenditures. These are typically combined with GDP projections based on age-specific labour force participation and unemployment ratios, along with productivity growth assumptions. While accounting frameworks of this type have proved useful, they necessarily lack the kind of policy modelling, detail and heterogeneity available in microsimulation models. 1 The microsimulation model used here is the Melbourne Institute Tax and Transfer Simulator (MITTS). This is a behavioural tax microsimulation model allowing detailed examination of the potential effects.
