Illicit drug use has created an enormous burden at societal, family and personal levels. Every year a significant amount of resources is allocated for treatment and the consequences of illicit drug use in Australia and around the world. Heroin is one of the major forms of illicit drugs that are used illegally. Several independent heroin treatment strategies or interventions exist and state-of-the-art research demonstrates their efficacy and relative cost-effectiveness. However, assessing total potential gains and burden from providing all treatment interventions or varying the mix of heroin treatments has never been attempted. Furthermore, the need to include multiple treatments, multiple important outcomes, and the chaotic nature of drug dependence means cost-effectiveness studies are not able to provide evidence on net benefit of providing heroin treatments over the lifetime. Evaluations of the current mix of treatment provision remain very limited. Thus, this paper will discuss an individual level model which addresses net social benefit over a lifetime, also known as individual sampling model (ISM), that can accommodate the complexity of individuals going in and out of multiple treatments and their corresponding costs and benefits arising from different treatments during the life-course of heroin users in the context of New South Wales (NSW) Australia. This model is intended to serve as an effective tool for economic evaluation and policy making in illicit drug area in Australia.