I stumbled across this sentence while reading a book:
It's not due in tomorrow.
it refers to a piece of homework.
After looking up the word "due" in several dictionaries, I suppose "due" means expected and "due in" is not a fixed phrase.
I wonder why they don't just say "It's not due tomorrow.". If a preposition is compulsory, why isn't it "on" because "tomorrow" is a day?