Introduced for use with tax returns for 2011, this Form 8949 was devised to accommodate the changes in IRS Form 1099-B that also became effective in 2011. Starting with stock sales made during 2011, Form 1099-B provides more information on the cost basis and whether the gains are long-term or short-term. This information is then used on Form 8949 to list each capital gain or loss transaction. The subtotals noted on this form are then used to complete Schedule D of the Form 1040 tax return for your aggregate gain or loss. Therefore, both Form 8949 and Schedule D are required to report sales of securities.
For more details, see the related article in the Tax Center.