My 1099-b does not have a cost basis in line 1e of the summary but it does on
on the detailed page with box B checked. Do I need to mail something in also because of this?
Thank you, E
No, you will not need to mail anything in, unless the IRS asks for it.
Brokerage statements will not always report the cost basis and/or sales category, even if the information is available right on the 1099-B. The IRS is receiving the 1099-B information from the broker, but is relying on you to report the correct cost basis and category.