While it sounds like an ideal income stream, there are more specific benefits of residual income. For instance, unlike a salary, someone does not need to remain tied to the same location in order to earn income. He can move halfway around the world and still make the same residual income as he would if he stayed in the same location as his business.
Residual income is calculated as net income less a charge for the cost of capital. The charge is known as the equity charge and is calculated as the value of equity capital multiplied by the cost of equity or the required rate of return on equity. Given the opportunity cost of equity, a company can have positive net income but negative residual income.