Residual income has two real definitions. Let’s look at those first. Residual Income is income that continues to be generated after the initial effort has been expended. Compare this to what most people focus on earning: linear income, which is “one-shot” compensation or payment in the form of a fee, wage, commission or salary. The other definition for residual income is not actually a type of income, but rather a calculation that determines how much discretionary money an individual has available to spend after most monthly bills are paid. We believe that income that exceeds your expenses is called PROFIT! So, we are going to use the first definition for the sake of this document.
The organizing principle behind this grouping, appropriate economic units, is relatively simple: if the activities are located in the same geographic area; if the activities have similarities in the types of business; or if the activities are somehow interdependent, for instance, if they have the same customers, employees or use a single set of books for accounting.
Regardless of which investment strategy you decide to pursue to earn residual income, an essential part of the investment process is careful due diligence of each opportunity as it arises and working hard to remove any pre-existing biases. Take your time to figure out which approach makes the most sense for you, and carefully calculate your residual income goals. Remember that diversification using different asset classes is one of the most effective ways to build stable and viable streams of residual income, and a profitable portfolio.

In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.
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