I use LVX and clear through IB. I did a risk reversal today and calculated my margin to be 14k. I just took the formula for short naked put and put it in excel to get the margin (https://www.interactivebrokers.com/en/index.php?f=marginnew&p=opt). When I check my margin through IB, the RegT margin shows 14k, but my initial margin is 35k and has slashed my excess liquidity by such. I had no margin previously and sufficient funds in the account. I called IB to inquire why this happened and how they calculated it but customer service was awful and provided me no answers. "I didn't write the code" and "I don't know but it's right" was all they could tell me. Can anyone help me out here?