Form 8949 Box E (Basis Not Reported to the IRS)

[hbkw01]

I have a broker provided tax summary form (from 2017 as I am working on an amended return).  For a long-term asset that was sold, one of the categories included for inclusion within Form 8949 is that Box E is checked and the cost basis was not "officially" reported to the IRS, but the form does include a cost basis for those assets although it was not included within box 1e (cost or other basis).  So, I have 2 questions. 1) If there is a known cost basis for these long term assets why would the brokerage not have reported the cost basis?  2) Since a cost basis was included on the summary from the broker, but not reported for whatever reason, can I add that cost basis to that sale?    Thank you.

[Bsch4477]

The broker is not required to report the cost basis for securities bought before 2010 even if they have the cost basis.  The IRS doesn’t want the purchase records from 2010, which can be deemed unreliable since the regulations specifically stated January 1, 2011.  Yes, use the cost basis as reported on the 1099-B unless you have reason to believe it is not accurate.

[hbkw01]

Most thankful.  Thank you.