The Australian government implemented a series of private health insurance (PHI) policy reforms between 1997 and 2000. As a result, the proportion of the population with PHI coverage increased by more than 35%. However, this study found significant evidence that the policy reform disproportionately favours high-income earners. In particular, the 30% premium subsidy represents a windfall gain for households which would have purchased PHI even without the rebate. The amount of such gain is estimated to be around $900 million per year, a large proportion of which went to higher income households.