No 1099-B for private company stock sale - what supporting documents must be submitted?

[CHL]

I recently sold stock I held in a private company.  They do not issue 1099-Bs.  In TurboTax Premier Windows desktop edition, I was able to enter the capital loss via the 'Step by Step' process.  However, upon reviewing the "1099-B Wks (No Financial Institution)" form, I noticed a checkmark for "Yes" in the "Taxpayer must mail in a statement with more details" at the bottom of the form. 

The only cost basis evidence I have is a spreadsheet showing historical share prices.  I also took a picture of the stock certificate before I turned it in to the company when I sold the stock. The image of the certificate has the number of shares and date acquired but no price (cost basis).  I calculated the capital loss based on the date of the stock certificate and the price of the stock on the date sold based on the spreadsheet of price history.

Questions:

1.  What details do I need to 'mail' in to the IRS and what address do I mail it to?

3.  Is the spreadsheet of historical prices and the stock certificate image sufficient proof for the IRS?

Many thanks!

[CHL]

...and let me add to my message above that TurboTax did not signal or remind me to mail in the supporting documents.  It was by chance that I noticed that requirement in the worksheet in 'forms' view.

[rjs · Accepted solution]

On Form 8949 is there an adjustment code M in column (f)? If so, that's why it's saying that you have to mail in a statement. The code M means that you entered a summary instead of entering each sale individually. Did you have more than one sale? If you enter one sale at a time it won't use adjustment code M and it won't tell you to mail in a statement.

[Mike9241]

you need to send in no supporting documents. if the IRS wants them you'll get a letter. each sale of stock purchased at different times needs to be entered separately. the 8949 box is C for short-term shares  - or F for long-term shares. the box code tells the IRS that neither the proceeds nor the cost basis was reported to them by the entity handling the transactions.

[CHL]

You're right!  I chose the "I'll enter one sale at a time" option for the one and only sale and everything looks good now.  Many thanks!

[CHL]

Thanks for your reply and the useful info.  Regards.