I have no statements for old stock purchases (done through reinvesting dividends) but I do have tax forms from 1988 showing that I had stock and have been able to figure out about how many shares I had (even though I know I bought some before that).  So here is my question: by 1993 I owned 2000 shares of  X stock.  In 2016 I sold 850 shares and I can trace back that I would have sold some from 1988, 1989 and 1990. Now what?  Do I just pick each amount (250 from 1988, 500 from 1989 and the rest from 1990) and how do you pick a date?  I know on the tax form I got this year, it only goes back to 2005 and I have very specific amounts from then on.  Is this something I should turn over to an accountant?