@bone true I am not a tax pro either and that disclaimer apply. I just stick in my futures brokerage tax form in Turbotax and it calculates it
like this. Just like I said it does. I am not sure what offsetting position your are referring to, but probably that's part of the equities side of the calculation, taking into account wash sales and what not. All I am saying is after one is done calculating the equities and futures side separately, they can be offset against each other (the ST & LT part). At least, that's what my understanding is, and that's what Turbotax is doing for me since forever, and I am yet to hear from IRS with any objections