I'm pretty sure it's 12 years of schooling after college. 4 years of medical school plus 6-8 years of fellowship. Thus 12 after college + 3 years to pay back debt + 7.5 years to get even is age 22 + 22.5 years = 45. Of course the reality is that someone who has worked at Microsoft for as long as the guy in the comparison is going to average more than 100K a year in compensation over 22.5 years. So my figure of the salaries evening out at 50 is pretty reasonable I think.