Opportunity and Sunk Costs

Opportunity and Sunk Costs explains which economic costs belong in a decision made today. Opportunity Cost measures the best feasible alternative given up by a choice. Sunk Cost identifies past spending that cannot be recovered through the current choice. Sunk Cost Fallacy describes the behavioral error of letting that unrecoverable past spending distort a forward-looking decision.

The distinction matters in investing, capital budgeting, pricing, restructuring, lending, and public appraisal. A project can have consumed substantial capital and still be worth continuing if its remaining benefits exceed remaining costs. Another project can look inexpensive in accounting records while using an asset or team that has a valuable alternative use.

Choose the Right Concept

These concepts are connected but not interchangeable. An owned building can have a sunk historical purchase cost and a current opportunity cost equal to the value of selling, leasing, or redeploying it. Past project spending can be sunk while the project experience provides useful new information about completion probability. A decision can continue rationally despite a large sunk cost when future value remains positive.

A Forward-Looking Review

1. Define the decision date and the alternatives still available.
2. Separate past paid amounts from future committed, avoidable, and incremental cash flows.
3. Estimate refunds, salvage, sale proceeds, exit costs, taxes, and contractual consequences.
4. Identify alternative uses of capital, assets, people, capacity, collateral, and time.
5. Compare future net values on a consistent basis, including risk, timing, liquidity, and constraints.
6. Reconcile new forecasts with earlier assumptions and actual results.
7. Keep the current recommendation separate from accountability for the original decision.
8. Document uncertainty and the evidence that would change the choice.

This workflow complements Capital Allocation, Net Present Value, and Cost-Benefit Analysis. It does not replace contract, tax, accounting, legal, technical, or risk analysis.

Common Traps

• Treating historical cost, book value, tax basis, and current recoverable value as the same amount.
• Calling an owned resource free because no new invoice is paid.
• Excluding future exit costs because the original project spending is sunk.
• Continuing solely to reach break-even on a historical purchase price or budget.
• Assuming cancellation is always correct after a loss.
• Using a higher-return alternative without matching risk, horizon, liquidity, and feasibility.
• Ignoring what past stages revealed about future costs, benefits, or execution risk.

The pages in this section provide general economic and financial education. They do not recommend whether to continue a project, sell an investment, restructure a loan, or choose a particular use of capital.

In this section

Choose a subsection first. Deeper term pages live inside each subsection, which keeps large topic hubs readable.