When you sell a share at a profit, you need to pay capital gains tax. However, this is usually lower than your regular tax rate. How much you have to pay varies depending on the country. In the U.S the capital gains tax is between 0-20%. In the U.K. you pay between 10-20% in capital gains tax. While in Canada the capital gains tax is as high as 50%. Be sure to read the rules that apply in your country and state.