Well put, cstfx.
Let me add this, briefly. Daal, have you ever placed any cash forex trades? More specifically, are you aware of what information a typical retail forex broker/dealer provides to you at year-end?
Here's why I ask. Let's accept, for the moment, your claim that Brazil taxes gross (profit only), rather than net (profit - loss) proceeds from trading, as you suggest... even though that doesn't make any sense whatsoever to those of us on the outside.
In the US, at least -- where you seem to be keen to conduct business -- the only document you'll receive at year-end (if you're lucky) is a 1099-INT, statement of net interest, either earned or charged, on your forex trading acccount. Neither you nor anyone else will ever receive anything showing your P/L... gross, net or any other kind. It's left up to... you guessed it... you, the trader, to correctly calculate your income from trading that forex account for the year and comply with your personal tax requirements, if any.
Given that basic year-end reporting reality in the retail forex world at this time, is it possible that you are kind of looking for a solution in search of a problem?