I rent out two single family homes. You need to learn about how to analyze your return on investment, get the places rented, and deal with repairs, problem tenants, among other things. If you don’t do your research, you could easily lose money. I have to spend a few days a year managing things, checking up on the properties, finding new tenants, but it is effectively passive. I buy in areas near big universities with stable real estate markets so there is always a fresh crop of new people moving into the neighborhood.
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.