I have asked this question in IB's board and hasnt got too much response so i might give it a try here. Here is the situation: I want to sell deep ITM long term put on some income trust to avoid forign tax withholding, so i need to be precise on how much interest i will be responsible for in order to determine whether to just buy the stock or sell ITM put. Let's use the real world data for illustration The trust pays 0.22 monthly current price is 17.80 july 22.5 put is quoted at 5.5/6.0 The margin on selling the options is premium received + 20% of market value which is 5.50+3.56 = 9.06 From my understanding, i wont be receiving any interest on the 9.06 margin The question i have is, does the 5.5 i received treated as cash and i will be able to use it right away to invest in something else or perhaps be eligible to receive interest from IB or do i have to wait for the options to expire in july before i can touch that 5.5?