For example, if you bought $30,000 in stock and it appreciated 3 percent per year for three years, you’ve gained $2,782 on top of your $30,000 invested — and if you sold, you’d pay taxes on that money gained. If you buy a $300,000 primary residence with a $30,000 down payment (representing 10 percent down) and it appreciated 3 percent per year for three years, you’ve gained $27,818 on top of your $30,000 invested — and if you sold, you’d be exempt from paying any taxes on that money gained.