Reporting 1099-B info

[monkeyfi]

I have a 1099-B automatically downloaded to my 2016 return from Fidelity with a transaction for which basis is not reported to the IRS and term is unknown.   Do I manually enter in the cost data and term or just submit on my return as reported from Fidelity.

[Critter]

You MUST fill in the missing information otherwise the IRS assumes a zero basis and a short term sale which is not in your favor.