Back in the 1980's I received lumps of stock each year as part of an employee stock ownership program.
I kept the paper stock certificates myself. For example lets say one lot was 10 shares and the price of the stock on the certificate date was $8 per share. So the cost basis was $8 and the total was $80. The next year I received 20 shares and the cost basis on those was $9 for a total cost basis value of $180. Several years later after I left the company, the stock split and I received another 30 shares of stock. None of those shares had any cost basis information but there was a date on the stock certificate. For those additional shares how do I calculate the cost basis? Do I use the price of the stock on the date on the stock certificate or do I add the total cost basis together (80 + 180 =260) and divide by the original number of shares (30) to get an average cost basis of $8.67 each before split and then divide by two to get a cost basis of $4.33 for each of the new shares. The cost basis of the first shares dropping to $4 and the cost basis of the second 20 shares dropping to $4.5. Which of these two methods is correct or should it be done some other way?
