I have one transaction that my broker reports N/A in fields TurboTax requires information: date acquired, cost basis, gain/loss amount. WHAT INFO DO I ENTER TO PROCEED?

[esteban-vorbeck]

IRS Instructions say REPORT on FORM 8949 CODE X. How/where do I get TurboTax to do that?

[fanfare]

You're not reading the instructions correctly.
here's what it says:
 If box 2 is blank and code X is in the "Applicable checkbox on Form 8949" box
near the top of Form 1099-B, your broker doesn't know whether your gain or (loss) is
short-term or long-term. Use your own records to determine whether your gain or
(loss) is short term or long term.

Your transaction will end up in category Box B or Box E

[Critter]

If your broker doesn't know when you bought it or how much you paid then you must fill in the missing information from your records ... use a best guess for the purchase price and choose any date prior to 12/31/2016 for the buy date ( this will make it long term automatically).