Mutual Fund cost basis

[Roberts]

What do you suggest for tax clients that have absolutely zero chance of coming up with a cost basis?

I had an example this week. Client bought a mutual fund in the 1950's and there is zero record of those purchases (fund company and investment firm destroyed the data during computer conversions). In the 60's they know they bought and sold some shares but they don't have a clue and again, mutual fund company says they have no record of it. Dividends and capital gains were re-invested for 50 years and the fund doesn't even have a record of payouts for the first 10+ years.

Now they need the money and need to come up with a cost basis. What do you suggest for clients like that? The reality is that the taxable gain they'll realize is pretty minimal since they paid taxes all those years on the gains and dividends as realized.

Edit: I'm 99% sure they have a loss! Looking back at reinvestments for the last 9 years, it's virtually impossible that they could have a gain and I'm sure the fund sold most of their holdings and turned the portfolio over realizing all gains.