Lesson 1, Topic 1
In Progress

Cost Classifications for Decision Making

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Costs can be classified for decision making. Costs are important feature of many business decisions. For the purpose of decision making, costs are usually classified as differential cost, opportunity cost, and sunk cost. It is essential to have a firm grasp of the concepts differential cost & differential revenue, opportunity cost, and sunk cost.

Differential Cost and Differential Revenue:

Decisions involve choosing between alternatives. In business, each alternative will have certain costs and benefits that must be compared to the costs and benefits of the other available alternatives. A difference in cost between any two alternatives is known as differential cost. A difference in revenue between any two alternatives is known as differential revenues. Differential cost includes both cost increase (incremental cost) and cost decrease (decremental cost). In general, the difference (cost and revenue) between alternatives are relevant in decision making. Those items that are the same under all alternatives can be ignored.

The accountant’s differential cost concept can be compared to the economist’s marginal cost concept. In speaking of changes in cost and revenue, the economists employ the term marginal cost and marginal revenue. The revenue that can be obtained from selling one more unit of product is called marginal revenue, and the cost involved in producing one more unit of a product is called marginal cost. The economists marginal cost is basically the same as the accountant’s differential concept applied to a single unit of output.

Opportunity Cost:

Opportunity cost is the potential benefit that is given up when one alternative is selected over another. To illustrate this important concept, consider the following examples:

Example 1:

Vicki has a part-time job that pays her $200 per week while attending college. She would like to spend a week at the beach during spring break, and her employer has agreed to give her the time off, but without pay. The $200 in lost wages would be an opportunity cost of taking week off to be at the beach.

Example 2:

Suppose that Neiman Marcus is considering investing a large sum of money in land that may be a site for future store. Rather than invest the funds in land, the company could invest the funds in high-grade securities. If the land is acquired, the opportunity cost will be the investment income that could have been realized if the securities had been purchased instead.

Sunk Cost:

A sunk cost is a cost that has already been incurred and that cannot be changed by any decision made now or in future.


Sunk costs cannot be changed by any decision. These are not differential costs and should be ignored in decision making. To illustrate a sunk cost, assume that a company paid $50,000 several years ago for a special purpose machine. The machine was used to make a product that is now obsolete and is no longer being sold. Even though in hindsight the purchase of the machine may have been unwise, no amount of regret can undo that decision. And it would be folly to continue making the obsolete product to recover the original cost of the machine. In short, the $50,000 originally paid for the machine has already been incurred and cannot be differential cost in any future decision. For this reason, such costs are said to be sunk costs and should be ignored in decision making.


  1. Explain cost classification for decision making?