Capitall gains liability for sale of foreign corporation

[Rosal42]

I am us citizen living abroad, with permanent residency status in Costa Rica. In 2001 purchased a corporation, the sole asset of which was a government lease on a beachfront property.

I built my house on that lot and ran my foreign business until May, 2022. I sold it (the stock, which by 2022 had acquired many more assets, eg, house, automobile, funiture) for $250,000. It was my only home. Of course in 21 years, I have spent at least that much for initial building, improvements, etc. I have no income other than Social Security benefits ($12,000 per year gross), I file a 1040 every year, and have not had to pay US income tax for many years. 
Will I be liable for capital gains taxes, considering I will need to find housing with the proceeds of my sale of stock? Thank you.

[RSUMan]

Let's say you purchased 100 shares of Beachfront Corporation which owned a lease on beachfront property in Costa Rica.  The question is what is your basis in those 100 shares.  Your basis includes what you paid for the stock in 2021.  If you made additional capital contributions to Beachfront Corporation to make improvements or to otherwise support the business, those payments may in fact increase your basis in your ownership position in Beachfront Corporation.

The fundamental equation for the sale of stock is Proceeds minus Basis equals Gain or Loss.

So you have $250,000 minus your Basis which is a number that you need to determine based on what financial transactions have happened over last 20 plus years.