You need to add expenses of sales and commissions to your original cost basis to calculate the cost or other basis amount. The TaxAct interview process does not ask for these items separately; you need to keep detailed records to complete this entry.
To access Form 1099-B and report cost or other basis in the TaxAct program (if you need help accessing Form 1099-B in the TaxAct program, go to our Form 1099-B - Entering Capital Gains and Losses in Program FAQ):
Per IRS Publication 550 Investment Income and Expenses (Including Capital Gains and Losses), page 64:
Form 1099-B transactions. If you sold property, such as stocks, bonds, or certain commodities, through a broker, you should receive Form 1099-B from the broker. Use the Form 1099-B to complete Form 8949 and/or Schedule D (Form 1040).
If you received a Form 1099-B for a transaction, you usually report the transaction on Form 8949. Report the proceeds shown in box 1d of Form 1099-B in column (d) of either Part I or Part II of Form 8949, whichever applies.
Include in column (g) any selling expenses or option premiums not reflected in box 1d or box 1e of Form 1099-B. If you include a selling expense in column (g), enter “E” in column (f).
Enter the basis shown in box 1e in column (e). If the basis shown on Form 1099-B is not correct, see the table How To Complete Form 8949, Columns (f) and (g), in the Instructions for Form 8949 for the adjustment you must make. If no basis is shown on Form 1099-B, enter the correct basis of the property in column (e). See the instructions for Form 1099-B, Form 8949, and Schedule D (Form 1040) for more information.
See this section of the publication for examples.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the webpage or document at the time it is accessed.