1099-B: "OTHER TRANSACTIONS - Cost basis not reported to IRS - Form 8949, (X)". But I can't find a sale category 'X' in TurboTax Premier download version 2018.31.24.245

[fanfare · Accepted solution]

Category X indicates the Broker does not know your Acquisition Date.

If your holding period is over one year, select LT (Long Term), otherwise select ST (Short Term)

OR enter the date from your own records.