Are you able to deduct the cost of purchasing a seat on an exchange (CME, CBOT, NYMEX, etc)? I have not been able to find anything about this online or on ET. Also, just out of curiosity if you lease a seat where are you writing off the expense. I have mine on schedule C, Part II, line 17 Legal and professional services.
No. When you sell the seat, you will incur long-term or short-term capital gains tax on the transaction as if it were a common stock.