What will be reported? Members have found that plan administrators, transfer agents, and brokerages vary significantly in how (or if) they track gain/loss and cost basis for the many complex HP-related stock events -- and what (if anything) they report to the IRS. Issues with major brokers

"Noncovered" Security -- Definition, Reporting Rules, vs. "Covered" Investopedia on "Noncovered" securities

FWIW, to date no member has indicated -- privately or on the HPAA forums -- that their returns have been questioned by the IRS due to how they reported the many extremely complex HP/HPE-related stock transactions. Save the documents and spreadsheets you used.

Using TurboTax for ESPP shares -- step-by-step with screenshots. Now v02 with Capital Gain Worksheet and Form 8949.

Be sure to save the documents you used -- plus, for future reference, a copy of the HPE/MFGP/"Seattle Spinco" letter This "Dear Shareholder" letter does not appear to have been actually sent to all shareholders. Members report that this cost-basis tracking recommendation was disregarded by some brokerages, plan administrators, and transfer agents -- and not uniformly followed by others.

And be sure to save -- under a different filename -- the spreadsheets you have modified and keep them for future reference when you sell shares, etc.

Amended return. You can file Form 1040X "...within 3 years (including extensions) after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later." IRS link  [When you launch a tax-prep app, it asks if you want to file an amended return.]

You're done!