A cost of illness (COI) study was undertaken to estimate the magnitude and range of lifetime effects associated with child maltreatment in Australia, using an incidence-based approach. Costs were primarily estimated through calculation of population attributable fractions (PAFs) to determine the marginal effects of child maltreatment on a range of outcomes. PAFs were then applied to estimates of expenditure, inflated to 2014-15 Australian dollars, projected over the life course, according to a baseline age of incident cases for child maltreatment in 2012-13, and discounted at 7% per annum. Sensitivity analysis was conducted using a best and lower bound estimate of incidence of child abuse. The best estimate of the total estimated lifetime financial costs for incident cases of child maltreatment in 2012-13 was $9.3 billion (a cost per child maltreated of $176,437), with a lower bound of $5.8 billion. The best estimate of lifetime costs associated with reduced quality of life and premature mortality (non-financial costs) for all incident cases of child maltreatment in 2012-13 was $17.4 billion, or $328,757 per child maltreated. The considerable lifetime costs associated with child maltreatment warrants an expansion of existing investment in primary and secondary prevention and targeted support services for children and families at risk. (C) 2016 Elsevier Ltd. All rights reserved.