IRS requires details to be listed on Form 8949,
or on your own forms (e.g. consolidated 1099-B) which have the same information and in the same manner as Form 8949.
Either way, if you choose to summarize, you have to mail the transaction details to the IRS within three business days of IRS accepting your tax return.
Form 8453 is just a cover sheet you will include when you have made the mail-in election. It is not to be signed.
Exception: if you summarize Category A or Category D, Form 8949 is not needed for transactions without adjustments. No mailing is necessary. TurboTax won't ask you about wash sales if you don't check the box.
As an active investor, be aware that your category Box A sales without adjustments do not require Form 8949, so there is no reason to import those transactions.
Instead use the "enter a summary" option to put your numbers on Schedule D Line 1a.
--
If you have wash sales, it gets more complicated since those adjusted transactions have to be itemized on Form 8949 and the summary totals adjusted accordingly.
Enter the wash sales on Form 8949, then use the subtotal results on the bottom of that form to know how much to subtract. Be sure to NOT check the adjustments box in the summary window.
TurboTax does not have an "import transactions with adjustments only" option ; it should !
