If a senior citizen (82) cashed in stock and received the proceeds, what legal

[naturalwoman2003]

(tax) obligation is required? What forms are needed?
Does it go on this year's or next years tax return? (check received this year)
How does this affect social secuirty benefits?
Also, person has not filed taxes since retiring 20 years ago. And the only source of income is SS.
Thanks for responding.

I have another question - is the net gain the amount of the check? If not, how can I figure it out?
Thanks piano. This is a case where a company demutalized (sp) and she became a shareholder back in 2004. As far as I know she never paid any money into it. I'm not clear on what was happening between 2004 thru 2008, as I didn't know about the stock, until she had cashed it in and received the check. I'll try and explain the best I can. After she became a shareholder in 2004 she did not purchased any more shares.
In comparing the the last statement she received before she cashed in the stock and the form after she cashed it in it appears she has a loss because the amount is smaller. Correct me if I'm wrong.