When you enter your 1099-B for Stock Sales, your Gain or Loss is reported on Schedule D in your tax return. TurboTax does this automatically for you after you enter all your stock sales.
The most important aspect in determining Gain or Loss is the Cost Basis of the stock you sold in relation to the Sale Price.
A. Your net loss is calculated on Schedule D and carried to line 7 of form 1040. You are only allowed to deduct $3000 of losses, each year, against ordinary income. So, line 7 will be not more than (minus) $3000. Any excess will carry over to next year.
In TurboTax (TT), enter your stock sales at: - Federal Taxes tab (Personal in Home & Business)