Student or Learner
I'd like to know if I can say this sentence. The meaning I want to convey is that I am talking with my friend about a task of which the deadline was yesterday.
It's possible to use 'You are supposed...', but with reference to a future obligation (that might be met): 'You are supposed to have done this by tomorrow'.
That one's more likely than the one I suggested in a general case, but I think people would use 'You are supposed to have done this...' to emphasize the process - meaning 'You should be well on the way to having it done by now'.