Form 1099 (in its various incarnations) is an information return that the investment company sends to the IRS to report certain types of transactions. It doesn't necessarily include all of the information that you need to report on your return, although there will be information that the IRS expects to see on your return.Form 8949 and Schedule D are used to report dispositions of capital assets on your tax return. Form 8949 is used to reconcile amounts reported on Form 1099 with the actual gains and losses that you report on Schedule D.You generally don't attach Form 1099 to your return, although if you have a large number of transactions to report on Form 8949 you have an option to prsummary totals on Form 8949 and attach the Form 1099 (or equivalent statement) to your return.You don't have to file Form 8949 - although you still must file Schedule D - when you have a capital gain distribution (reported on Form 1099-DIV). You also don't have to file Form 8949 if all of your 1099-B and 1099-S have basis reported to the IRS for all transactions, you have no adjustments to make to the reported basis, and you have no nondeductible wash sales.