ATM/ ITM whatever - if you are a buyer of an option you have to pay full price.. where does the question of Margin come in to it? - If you area seller of an option ( naked) then yes then margin comes in to picture - If you are a buyer of a Option spread then again you have to pay full price of the spread - If you are a seller of a Option spread then your max loss is fixed and you need cash = max loss - How much for a long option.. based on expiry time and ATM/ITM just check few live prices on your platform