In India all stock and index options are European in nature. That means such options cannot be exercised before the expiry, unlike American options. Let us say you are holding a Reliance 920 call option on the F&O expiry day which you had purchased at a premium of Rs.21. On the expiry day, the stock is quoting at Rs.965 but the call option is quoting at a discount at Rs.43. Remember, not to leave the option to expiry. If you square up the option at Rs.43, you will only pay 0.05% STT on premium value but if you leave to expiry, it will be treated as a stock (being an ITM option) and will be charged STT at 0.125% of actual value. That can make a huge difference so remember to always square your call options on expiry date even if the price is below the intrinsic value. Also when you own options, the time value becomes zero close to the expiry. As well close out the position when you have intrinsic value and time value in your favour. That is a trade off that you need to look at.