From what he describes, creating passive income definitely does not sound easy. It requires a serious ramp-up -- often requires 80- to 100-hour workweeks in the beginning, says Flynn. But once up and running, and depending on the content, some sites take fairly minimal maintenance. Green Exam Academy, the LEED exam study site he launched in 2008, takes just him four to five hours a month to maintain but brings in $250,000 annually.
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.