The legitimacy of inequality concerning the income distribution in market economies is based on the assumprion of a dominant individual performance and the assumed existence of equal chances. To test the empirical relevance of this assumption requires the analysis of the determinants of the income level as well of income mobility. Whereas the scientific discussion traditionally is centered on the lower income range and poverty, the upper range of the income distribution with high income is rarely investigated. This is valid the more the self-employed are regarded. The term study is analyzing the determinants of high working income of the self-employed (200% of mean as the wealth line) in Germany. We distinguish between individual (human capital, working hours) and structural (social origin, discrimination, region etc.) determinants of the income level. Theoretical background are the prominent income theories. Microdatabase is the socio-economic panel (SOEP). With multivariate paneleconometric approaches (Probit- and Tobit panel model) the single hypotheses are tested. Central result: high income is above all a question of social origin. The social background influences via education and social networks the level of working income. Individual factors compared to the structural influences are rather of lesser importance in determining high income of the self-employed.