On the IB margin site it says for a short box i will be charged margin according to this rule: Maximum (((Long Call Price + Long Put Price - Short Call Price = Short Put Price) * -102%), (Long Call Strike - Short Call Strike)) But in the margin preview for a 100 point ES($50) it says only $200ish. iirc all of these futures options are still margined like stock, so would help my cash balance. Anyone with any boxes with IB tell me what their margin requirement looks like? Apologies if i am missing something obvious.