One of the main features of health insurance is moral hazard, as defined by Pauly (1968); people face incentives for excess utilization of medical care since they do not pay the full marginal cost for provision. To mitigate the moral hazard problem, a coinsurance can be included in the insurance...

In this paper we discuss the efficiency properties of insurance markets where supplementary private insurance is allowed to exist together with a compulsory government insurance plan. Our main conclusion, which is contrary to both those of Besley (1989) and Selden (1993), is that in a simple...