Yes, upload your entire 1099 composite, including transactions into TurboTax. Then you should not be asked to mail 8453 for 1099-B summary statements in the future.
If you reported your investment sales using the summary total method, then you will have to send supporting documents (I.e Form 1099B). Its possible you may have chosen this method unintentionally as it is usually reserved for taxpayers with large volumes of transactions who don't want to list every transaction or are unable to import because of the volume.
You do not really need to mail Form 8949, but you do need to mail your supporting statements, such as your brokerage statements (Form 1099B) and Form 8453.
When you use this summary method of reporting (i.e. you just entered your summary totals and not each individual transaction), in some cases, the IRS still wants you to send the same details that are shown on Form 8949 (i.e. sales date, cost, sales price, adjustments, etc) but they allow you to send supporting statements instead of actually filling out every single transaction on Form 8949.
Most people send their 1099-B forms received form their brokers as these usually contain all the information for the transactions
.
Note: In limited situations, you’re allowed to summarize investment sales without providing complete details, but TurboTax will tell you when your sales meet this criteria and will not prompt you to mail any statements.
