The extent of social health insurance (SHI) and supplementary private insurance is frequently analyzed in public choice. Most of these analyses build on the model developed by Gouveia (1997), who defines the extent of SHI as consequence of a choice by self-interested voters. In this model, an indicator reflecting individuals' relative income position and relative risk of falling ill determines the voting decision. Up to now, no empirical evidence for this key assumption has been available. We test the effect of this indicator on individuals' preferences for the extent of SHI in a setting with mandatory SHI that can be supplemented by private insurance. The data is based on a DCE conducted in the field with a representative sample of 1538 German citizens in 2012. Conditional logit and latent class models are used to analyze preference heterogeneity. Our findings strongly support the assumptions of the models. Individuals likely to benefit from public coverage show a positive marginal willingness to pay (MWTP) for both a shift away from other beneficiary groups toward the sick and an expansion of publicly financed resources, and the expected net payers have a negative MWTP and prefer lower levels of public coverage.