Why sunk cost is not considered as relevant cost?
Christopher Davis
Updated on February 20, 2026
1. Sunk costs (past costs) or committed costs are not relevant. Sunk, or past, costs are monies already spent or money that is already contracted to be spent. A decision on whether or not a new endeavour is started will have no effect on this cash flow, so sunk costs cannot be relevant.
Can a sunk cost be a relevant cost?
A sunk cost is not a relevant cost for decision making. Whether a cost is relevant or irrelevant depends on the decision at hand. A cost may be relevant to one decision and that same cost may be irrelevant to another decision. A sunk cost, however, is always an irrelevant cost.
Are sunk costs relevant in capital budgeting?
Capital budgeting decisions are based on current and future incremental cash flows and not any past cash flows. Therefore, in calculating net initial investment outlay, analysts need to ignore the sunk costs but include opportunity costs in their analysis.
Are sunk costs Incremental?
Non-relevant sunk costs are expenses already incurred. Because the sunk costs will remain regardless of any decision, these expenses are not included in incremental analysis. Relevant costs are also called incremental costs because they are only incurred when an activity of relevance has been increased or initiated.
What is an example of incremental cost?
Incremental cost is the extra cost that a company incurs if it manufactures an additional quantity of units. For example, consider a company that produces 100 units of its main product and decides that it can fit 10 more units in its production schedule. That means the cost per glass bottle you incur is $40.
How is sunk cost ignored in relevant cash flows?
On a relevant cash flow basis, we do not need to be concerned with what has been paid in the past, so the $1,000 per year paid in the past is a sunk cost and can be ignored from relevant cash flows. What about the $1,000 per year in the future if Mrs Clip continues with the advertising?
Is there such a thing as a sunk cost?
Therefore, it is not a sunk cost. Sunk cost is also known as past cost, embedded cost, prior year cost, stranded cost, sunk capital, or retrospective cost. Suppose you buy a ticket to a concert for $150.
Why are Sunk Costs excluded from future decisions?
In both economics and business decision-making, sunk cost refers to costs that have already happened and cannot be recovered. Sunk costs are excluded from future decisions because the cost will be the same regardless of the outcome.
Why do you need to ignore the Sunk Cost Fallacy?
The company should not continue with the product launch and the initial marketing study investment should not be considered when making decisions. The sunk cost fallacy reasoning states that further investments or commitments are justified because the resources already invested will be lost otherwise.