Cost basis for surviving owner's security
In an account jointly owned by father and son, there was one security and one money market account. The father was the primary owner of the account. The father died in 2012 and son became the surviving owner of the account. Son moved the security to another account and subsequently sold it in 2012. Is the cost basis of that security the father's death date? Or because the son jointly owned the account before his father's passing, is the cost basis linked to the actual date that the father purchased the security--a date that not known without research by the surviving son.