Many nations have established workers' compensation systems as a feature of their social protection system. These systems typically provide time-limited entitlements such as wage replacement benefits and funding for medical treatment. Entitlements may end for workers with long-term health conditions before they have returned to employment. We sought to determine the prevalence of transitions to alternative forms of social protection, specifically social security benefits, among injured workers with long-term disability, when workers' compensation benefits end. We linked Australian workers' compensation and social security data to examine receipt of social security payments one year before and after workers' compensation benefit cessation. Study groups included (1) injured workers whose workers' compensation benefits ceased due to reaching a 260-week limit introduced by legislative reform (N = 2761), (2) a control group of injured workers with at least 104 weeks workers compensation income support (N = 3890), and (3) a matched community control group (N = 10,114). Adjusted binary logistic regression examined the odds of transitions to social security in the injured worker groups relative to the community control group. Within 12 months of workers' compensation benefit cessation, 60% (N = 1669) of the exposed group received social security payments, of which 41% (N = 1120) received the unemployment allowance and 19% (N = 516) the disability pension. Among the work injured control group, 42% (N = 1676) received social security payments after workers compensation benefits ceased. Transitions to social security payments were significantly more common than community levels for both exposed (OR 25.0, 95%CI = 20.7, 30.1) and work injured control groups (OR 4.7, 95%CI = 4.2, 5.3). Many injured workers with long-term health problems transition to social security when their workers’ compensation benefits cease. Transitions were more common among workers whose claims ended due to legislative reform which time-limited benefits. Design and implementation of system level policy reform should consider the social and economic impacts of transitions between separate social protection systems.