Policy makers and advocates in industrialised economies have increasingly couched arguments for addressing homelessness in cost-offset paradigms. In the USA, there is a robust body of evidence demonstrating cost offsets of supportive housing, whereas rigorous evidence from the UK, Europe and Australia is limited. The present article contributes to the evidence base with results drawn from a linked administrative data-set including: police, prison, probation, parole, courts, emergency department, hospital admitted patients, ambulance, mental health and homelessness services data. The results show that in twelve months when people were homeless, they used on average $48,217 (£25,776) worth of government services; in the twelve months as tenants of supportive housing, the cohort used on average, including the cost of supportive housing, $35,117 (£18,773) in government services. Although social work only infrequently draws on cost arguments to substantiate practice and intervention, the article argues that cost-offset evidence is consistent with social work’s commitment to evidence base practice. Moreover, analysis of services that people use when securely housed compared to homeless adds further evidence to demonstrate that people’s actions, and their status as clients, is mediated by resources and opportunities available.