IRS requires details of your SELL transactions to be supplied on some Form 8949,
or on your other forms (e.g. consolidated 1099-B or spreadsheet) which have the same information and in the same manner as Form 8949.
Either way, if you choose to summarize only, you have to mail the transaction details to the IRS within three business days of IRS accepting your e-Filed tax return. (unless you have attached a PDF of the transactions details to your e-Filed return. TurboTax Online will ask for it).
This is the "Mail-in option".
Detail Reporting Exception: if you summarize Category A or Category D, Form 8949 is not needed for transactions without adjustments. No mailing is necessary.
The exception does not apply to wash sales, since they have an adjustment.
Form 8453 is just a coversheet that identifies your situations that require mailing of paperwork.
