Residual income is a measure of financial efficiency and can be used to rate anything that generates income. You can calculate the residual income of a business, a department within a firm, a stock portfolio or even of yourself as an earner. A negative residual income means that the resources at hand are used poorly.
Opportunity cost is the basic concept at the heart of residual income. Opportunity cost refers to what you are giving up to use an asset for a particular project or investment. Let's say you start with $100,000 cash in your stock portfolio and grew that money to $104,000 by spending only a few hours per month trading stocks. Now $4,000 in profit may look just fine when you consider that you only worked, say, 20 hours for it in total. However, once you consider your opportunity cost, your little hobby will not look nearly as profitable. If banks are paying six percent for risk-free certificates of deposit, your $100,000 would have grown to $106,000 simply by depositing it in a bank. Your opportunity cost is $6,000
Residual Income equals net income minus opportunity cost. So in the stock trading example, your residual income is $4,000 minus $6,000 or negative $2,000. As you can see, an investment can produce negative residual income even if it helps your money grow . A negative residual income means that you could have done better by another, risk-free approach. Some analysts refer to residual value as Economic Value Added. If your residual value is negative, you are not truly adding value with what you are doing.
In many instances, a business project consumes far more resources than meets the eye. Assume you are running a dog grooming business from the first floor of your two-family house and that your daughter is helping you over the weekends. The business is making $50,000 per year and you want to know whether this represents a positive or negative residual value. In this case, you must deduct from $50,000 all opportunity costs which include the money you would make if you rented the first floor of your house to a business; how much you plus your daughter would earn if you invested the same amount of time and effort into a regular job; and how much the total assets owned by the business would return every year if they were sold off and the cash proceeds were held in a bank account.
Large corporations often use a higher rate than the risk-free interest rate when calculating the residual value of individual departments or an entire firm. They often called this rate the required rate of return or minimum acceptable rate of return. There are various ways of calculating such a rate, but the main reason it is almost always higher than the rates offered by certificates of deposit is the higher risk involved in a business. After all, investing money in even the safest corporation involves some risk of never again seeing part or all of your money again, whereas a bank deposit is government guaranteed and virtually fail-proof. Therefore, businesses consider themselves to be adding economic value only if they can surpass a higher benchmark than the risk-free interest rate offered by banks.
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