Cost basis of old stuff is always a problem. I don't know how anyone ever figures out the cost basis for dividends that have been reinvested for years. I have a mutual fund that I bought over 50 years ago. I've added money over the years as well as reinvested all the dividends. Unless I am willing to pick a cost basis out of a hat, I can never sell it. I think it will be my estate's problem.
Post 2011 the brokers/transfer agents are required to keep all of that information.
Pre 2011 my suggestion is to look at whatever old statements you have or can get. They frequently have your basis. Or if you still have your old tax files frequently the 1099's have an additional statement showing the annual invested/reinvested amounts. If you don't have records back that far it is a problem. You can sell and use a zero basis. That isn't as bad as it sounds. In many cases folks are in the zero-percent capital gains bracket (or can plan to be) so there may actually not be any tax. Or perhaps you could estimate the basis and rely on the https://www.law.cornell.edu/wex/cohan_rule ... no one likes to do that but it's not wacky. (Consult with a profession before doing so.)
Under current (long-standing) law, your estate won't have a problem. Basis is stepped up (or down) to the fair-market value on the day you die. So the estate/heirs can sell immediately at little but knowable gain. https://www.law.cornell.edu/uscode/text/26/1014
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
