To Amir,
Actually, there are no specific tax regulations governing taxes on forex trading results yet. Even so, you can voluntarily report it. Regarding the amount, we think this follows general tax rules.
Tax regulations state that anyone with an income of more than Rp. 54 million in a year is obliged to pay taxes. Thus, if you feel that your net income/profit from forex trading in a year has exceeded that amount, you may report your taxes.
Hopefully this can help.