Thanks @Anonymous .
I collected all the information I needed. Looks like there are two issues in my 2017 tax:
1) I forgot to file one of my 1099B (from Charles Schwab).
2) The 1099B from ETrade reports "Cost Or Other Basis" for the stock I sold in 2017 as 0. But also ETrade issued a "Stock Plan Transaction Supplement" document in which it reports 0 as "Cost Basis" but "n > 0" as "Adjusted Cost Basis" for the stock I sold with loss.
The letter, I received from IRS, says "If you have cost basis for the stock transactions in question, provide a completed Schedule D, Capital Gains and Losses, along with a completed Form 8948, Sales and Other Disposition of Capital Assets....
I wonder if I could use Turbo Tax to amend my 2017 tax and send the two forms back to IRS?
Do I need to send the 1099B and "Stock Plan Transaction Supplement" as well?
