Hello, I have purchased a stock through an Employee Stock Purchase Program (ESPP) over many years. I ended up selling but the stock purchases were so old that my broker statement says Undetermined Term, B or E (basis not reported to the IRS). How do I find the cost basis? What justification, documentation does IRS require? Thank you!
At this point you just have to make the best guesses you can and support them. Your problem is compounded by the special reporting required when stock acquired via an ESPP is sold, i.e., the need to determine if the sale of the stock creates reportable compensation, which gets added to the basis of the stock sold.
If the cycle of stock purchases was regular, e.g., money was deducted from paychecks throughout a calendar quarter with the purchase occurring at quarter end, and assuming the stock was publicly traded, then you could use the stock price at each quarter's end as a reasonable approximation and apply the ESPP discount to that. In the unlikely event the IRS ever questioned the basis used you'd bring out your supporting worksheets showing how you developed your figures.
This is why keeping the quarterly or annual stock purchase statements are so very important ... never rely on someone else keeping your records for you. See if you can get anything from the employer for the prior year basis. If you cannot, best guess using any information at your disposal is all you can do at this late date.