I do not disagree with the previous answer by Thomas, but I wanted to add some information that may help. The point is that you did correctly report the tax event already, even if there is an amount on the 1099-B. There is no need to amend or re-do any return. What is helpful is knowing that if an erroneous 1099 such as this is received, you can add a Statement (typed explanation attached to the end of your 2019 return) that says something along these lines... The Amount reported on Form 1099-B from X---Co. is $______. This amount is disputed because: I already reported this transaction when it actually happened in 2018. The amount I am reporting on my 2019 Form 1040 is therefore $-0-. It is important to include the Form or Schedule that it WOULD have been reported on with your return, and have a 0 on the appropriate line with the phrase "See Attached Statement."
It is a strategy that works in other applications, as well. If a 1099 is received in your SSN but the amount was really your Company's transaction or responsibility, you may include a statement showing "Amount reported on 1099" "Less: Amount included on tax reporting of affiliated business" Thus, "Amount reported on this 1040 equals $-0-."
