Explicit, Implicit, and Sunk Costs

Good decisions compare how future benefits and costs differ across available actions. That requires more than collecting receipts.

An explicit cost is a monetary payment to another party: wages, ingredients, electricity, or rent. An implicit cost is the opportunity cost of a resource the firm owns, such as the owner's labor or a shop space that could be rented out. Both are economic costs because both sacrifice an alternative.

Sunk costs look backward

A sunk cost has already been incurred and cannot be recovered. Because every current choice leaves it unchanged, it should not affect the choice. A nonrefundable 5,000 design fee remains part of the project's history but is irrelevant to whether spending another 2,000 will generate 3,000 of future benefit.

Do not confuse fixed and sunk. Next month's unavoidable lease payment may be fixed over the month but not yet sunk if cancellation is possible. A machine's purchase price may be historical, but its resale value is a current opportunity cost because choosing to use it means giving up the sale.

Use incremental comparison

For a current decision, calculate

Include future explicit payments and implicit alternatives that differ between choices. Exclude amounts that remain identical. This prevents the sunk-cost fallacy: continuing merely because much has already been spent.

Information is not always useless after purchase. A survey's payment may be sunk, yet its findings can change expected future revenue. Ignore the unrecoverable payment, not newly learned evidence.

Build a relevant-cost ledger

An evening café service would earn 9,000. Future wages, ingredients, and electricity total 5,000. The owner gives up freelance income of 1,500, and equipment could otherwise be rented for 700. Relevant economic profit is $9,000-5,000-1,500-700=1,800$, so the service is worthwhile under these estimates.

A 4,000 nonrefundable survey paid last month does not enter this comparison. Subtracting it would make the project look unprofitable, but the payment occurs whether the café opens tonight or not. Its information may remain useful; its payment is sunk.

Ask one question for every cost

Would this amount change if the firm chose the other available action today? If yes, include it, whether paid or implicit. If no, exclude it from the forward-looking comparison. This question is more reliable than memorizing labels because the same lease can be avoidable in one decision and fixed in another.