Background The impact of mental disorders has been assessed in relation to longevity and quality of life; however, mental disorders also have an impact on productive life-years (PLYs). Aims To quantify the long-term costs of Australians aged 45–64 having lost PLYs because of mental disorders. Method The Survey of Disability, Ageing and Carers 2003, 2009 formed the base population of Health&WealthMOD2030 – a microsimulation model integrating output from the Static Incomes Model, the Australian Population and Policy Simulation Model, the Treasury and the Australian Burden of Disease Study. Results For depression, individuals incurred a loss of AU$1062 million in income in 2015, projected to increase to AU$1539 million in 2030 (45% increase). The government is projected to incur costs comprising a 22% increase in social security payments and a 45% increase in lost taxes as a result of depression through its impact on PLYs. Conclusions Effectiveness of mental health programmes should be judged not only in terms of healthcare use but also quality of life and economic well-being.