What you mean?
I didn't withhold anything from forex gains due to my write-offs from penny stocks.
Even after this years gains, I should still have more write off available, and they withheld like 30% from my job in NY which I expect back.
I'm not really a tax guy, so give me more details :D
To be successful in the trading game, find a sound strategy and then learn and understand the rules of your strategy.