**Abstract**

Almost all health care services in the Slovenian basic benefits package are paid for from two financial sources: compulsory and complementary health insurance (CHI). Although this is unusual, around 90% of the population is insured under CHI. CHI covers the costs of copayments for most of the services. One of the advantages of the CHI is that it enables the public sector to shift the costs of service onto the private sector, which can compensate for the higher costs through premiums. Its administrative costs are low, the risk selection is low due to the equalisation schemes in place, and costs of copayments for the socially weak are covered by the state budget. Out-of-pocket costs are low due to most of the population being insured in CHI. On the other hand, there are many disadvantages of this unique amphibian health system. Besides the higher complexity and costs of such a health insurance system, CHI premiums are flat and regressive. The voluntary nature of CHI is highly questionable as the copayments can be as high as 90% of the total service costs. And last, but not least, CHI removes an incentive for the providers and payer to aim for efficient services.

**Keywords:** complementary health insurance, Slovenia, risk selection, inequality, efficiency
