Residual value also figures into a company's calculation depreciation or amortization. Suppose a company acquires a new software program to track sales orders internally, and this software has an initial value of $10,000 and a useful life of 10 years. To calculate yearly amortization for accounting purposes, the owner needs the software's residual value, or what it is worth at the end of the 10 years. Assume this value is zero and the company uses the straight-line method to amortize the software. Therefore, the company must subtract the residual value of zero from the $10,000 initial value and divide by the asset's useful life of 10 years to arrive at yearly amortization, which is $1,000. If the residual value were $2000, the yearly amortization would be $800 ($10,000 - $2,000/10 years).

^{Great post Jim. While it is convenient to lump the entire dividend income as one passive stream, in reality, it is several. If you have 30 companies across 10 major industry sectors, each paying you dividends, then you can consider having 30 streams or at least 10 passive streams, from each of the diverse industry sectors. I find this more diverse than relying on rental income from one investment property tied to one location and one good tenant. Your point about website is absolutely valid – will be great to have Ten Factorial Rocks worth 7 figures in less than 5 years as you have done! }

When most hear the term residual income, they think of excess cash or disposable income. Although that definition is correct in the scope of personal finance, in terms of equity valuation residual income is the income generated by a firm after accounting for the true cost of its capital. You might be asking, "but don't companies already account for their cost of capital in their interest expense?" Yes and no. Interest expense on the income statement only accounts for a firm's cost of its debt, ignoring its cost of equity, such as dividends payouts and other equity costs. Looking at the cost of equity another way, think of it as the shareholders' opportunity cost, or the required rate of return. The residual income model attempts to adjust a firm's future earnings estimates, to compensate for the equity cost and place a more accurate value to a firm. Although the return to equity holders is not a legal requirement like the return to bondholders, in order to attract investors firms must compensate them for the investment risk exposure.

*Though it can take a while to build up enough cash to put a 20% down payment on an investment property (the typical lender minimum), they can snowball fairly quickly. The key here is to correctly project income and expenses in order to calculate cash flow (the free cash you can put in your pocket after all associated property expenses have been paid). However you have to be sure to include the cost of a property manager in your calculations unless you want to manage the property yourself. Even with a property manager, you may be required to make large repair decisions every now and then – so while this is not a 100% passive activity, you are not directly trading your time for money like traditional employment.*

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.