How does the option work if both calls in the vertical call are in the money?
Do I have to have the capital to buy 100 shares of that stock in order to make a profit or could I just get the difference?
First, congrats, if both calls of a bull vertical spread are in the money (ITM) then you are in the max gain area. Second, I always (ok, maybe 95% of the time) treat vertical spreads as one position and open or close both strikes in a single transaction. Third, it depends on how much time is left in the option.
Assuming that there is still time remaining (i.e. it’s not the expiration date) you can close both positions at the same time for just the difference in the spread.
If, however, it’s the day after expiration and you don’t have enough capital in your account to buy 100 shares, you might get a nasty gram from your broker for not monitoring (closing) the positions before automatic exercise.
Only in rare situations would I allow an option to expire ITM. Normally I try to close verticals within the last 7-10 trading days.