We study labour market outcomes by formal differentiation at upper secondary and tertiary level in Finland. Using full population register data, we take individuals born in 1976 and explore their socio-economic status and the probability of unemployment by educational qualifications and social origin in early adulthood (age 30) and at occupational maturity (age 40). We differentiate based on the level of maths, the most consequential subject choice at general upper secondary education, and show that subject-level choices divert students to stratified tertiary-level degrees and labour market positions net of prior school performance, social origin and gender. In addition, we show that educational performance and qualifications mediate the association between social origin and socio-economic status by 81-83%, leaving around one fifth to unobserved social origin differences. We also find that there are no major differences between upper secondary school tracks with respect to experiencing unemployment at age 30 or 40. Moreover, further educational degrees do not appear to provide additional protection against unemployment than having obtained an upper secondary qualification.