Yes, the collateral margin changes according to price variations in the security.
For intraday option writing, can I use whole of pledged margin or 50% cash rule is applicable to intraday as well.
@samurai Yes, you can use the entire pledge for intraday option writing. The 50:50 is applicable only for overnight F&O positions.
You can check this post for Pledge-related queries.
@ShubhS9 suppose I take a hedged position intraday. Sell an otm nifty option worth 500 and buy an otm nifty option worth 200. the hedged margin comes to around 25k. Now how much of this will be taken from the pledged margin as pledged margin cant be used for option buying. Should I have Rs. 200 in cash and the rest 24.8k will be used from the collateral margin?
Yes, the amount needed to buy options should be available in cash.
No, the option credit can be used to fund the buy option trade if buy premium is less than sell premium.