Capital losses are deducted from ordinary income, not from taxes. You can deduct a maximum of $3000 of capital losses a year from ordinary income. For futures trading reporting Form 6781 and Schedule D are used.
For some there is a carry over possibility as well. Note the loss when you file to establish the possibility of a carryover. Commonly, sometimes lousy traders find mentors. then the mentor has an additional task of explaining the attitude of the government (local, state and fed) about how modern "Robin Hooding" works. there is No Way you can give away profits and not pay taxes on profits after a certain point. When you try to trade via a NFP to keep the tax money, then you have the problem of the brainless non incentivized IRS supervisors and congressional IRS liaisons. You have to trap them and mix them up so they make errors. They give up. It is best to find an established NFP or NGO and just make money for them. you do not need that kind of money anyway and why let the government spend it foolishly. One small tip. There are class action suits occasionally where people collect from the instrument mismanagement(stock of a corporation). If you trade in the period where the fault occurred, you cannot participate in the class action if you position traded the stock and made money. People in class actions and their lawyers are not willing to share with profit makers. Although, it is a very humorous process of getting screwed by losers whop bet on losers.
Section 1256 contract gains and losses (futures) are "capital gains and losses" with lower 60/40 tax rates - 60% is long-term capital gain even on day trade. Loss carryback election: Many traders don't realize you can elect to carry back a Section 1256 loss 3 tax years, but only against Section 1256 gains. At tax filing time, make that loss election in a box up top on Form 6781.