It is a well-established finding that social origin matters in the transition to graduate education and that social inequality in this regard is shaped by previous educational pathways and rational decision-making. This study is situated within the German context, where bachelor’s degrees were introduced during the Bologna Process, and extends previous research on the transition from bachelor’s to master’s programs in three ways: first, I draw on prospectively measured estimations of costs, benefits, and success probabilities to analyze their relevance in explaining social inequality. Second, I differentiate between intentions for immediate enrollment in a master’s program and delayed enrollment which might be especially attractive to students from low social origins. Third, I assume that many students consider a master’s degree as the only viable option, and therefore ignore high costs or a low probability of success in their decision. The analyses are based on data from 8166 bachelor’s students in the third year of their studies in German higher education (National Educational Panel Study, Starting Cohort 5). First, decompositions reveal that preceding educational trajectories and rational calculations explain about three quarters of the social origin gap. Second, multinomial regressions show that the intention for delayed enrollment in a master’s program is less socially selective than for immediate enrollment. Third, I estimate how costs and success probabilities interact with expected benefits of a bachelor’s degree. If students expect very low returns from a bachelor’s degree, estimations of costs and success probabilities have at best minuscule effects on their plans.