Hi All I am having some trouble working out the IB margin formula which is: 100% * option market value + (20% * underlying market value - out of the money amount or 10% * strike price, whichever is greater) or $2.50 * multiplier * number of contracts, whichever is greater. Now, If I have 1 short Put open position on XYZ which is at a stock price of $80, and my short position has a strike of $70, can someone calculate the margin requirment? Thanks!

1) Take option premium 2) add 0.20 * (8000 -1000) or add 0.10 * 7000 or add $250 whichever of the three is greater. In this case, it's option premium + 1400 Mark

CBOE site has a margin calculator that you may find useful. Fill in your info(prices, strategy, etc) and it will tell you what the requirement is