I sold stock & do not have any info to determine cost basis. I cannot make it up. There is no information available at all. what to do?

If you know when you bought it, you can look up the closing price on the date you bought it. If you inherited it at someone's death, the cost basis would be the closing price on the day it was transferred to you. IF someone gave you the stock, the cost basis would be the price they paid for it. IF you have none of this information and you are unwilling to make it up, then you have to pay taxes on the full amount you sold it for. (Cost basis $0.00). I would make a reasonable guess.

See the market.

If you have a purchase date then you can find the information. You may need to go back on microfiche for the Wall St. Journal if it goes back before the information on the company's shareholder information section on the company website. If they are still in business you can call the shareholder information number and they can probably find it for you.

Unfortunately, you have to use zero basis.

You can guess - and if it was bought over a long period of time, you write "varies".

If you don't have the info, neither does the IRS. So who's to say. And if you're not dealing with a HUGE sum, I doubt anybody cares.

Check newspaper archives for the price when you bought it.