Relevant Costing and Short-Term Decisions

Introduction

Managers routinely decide whether to manufacture a component or purchase it, accept a one-time order, suspend an operation, replace equipment, or process a product further. These decisions are described as short-term because they usually affect existing capacity and resources over a limited planning horizon. Nevertheless, their consequences may extend to product quality, employees, customers, suppliers, and organizational reputation.

Relevant costing directs attention to the revenues and costs that change because of a decision. It does not imply that other accounting information is inaccurate. Rather, financial accounting costs prepared for inventory valuation or external reporting may not correspond to the economic consequences of a specific managerial choice.

The central principle is:

Relevant-cost analysis should support—not replace—managerial judgment. Capacity effects, uncertainty, strategic dependencies, ethical duties, and qualitative considerations must also be evaluated.

Learning Objectives

After studying this chapter, students should be able to:

1. Distinguish relevant, incremental, avoidable, sunk, committed, and opportunity costs.
2. Construct differential analyses without being misled by allocated fixed costs.
3. Evaluate make-or-buy, outsourcing, special-order, shutdown, replacement, and further-processing decisions.
4. Incorporate capacity constraints and opportunity costs into short-term decisions.
5. Apply sensitivity analysis, expected values, and scenario analysis under uncertainty.
6. Evaluate qualitative, strategic, governance, and ethical consequences.

1. The Relevant-Cost Framework

1.1 The two tests of relevance

An item is financially relevant only if it passes both tests:

1. Future test: It will be incurred or received after the decision.
2. Difference test: Its amount differs between alternatives.

A future cost that remains identical under every alternative is irrelevant. Similarly, a past cost cannot be altered by a current decision.

For alternatives A and B, the differential effect of choosing B rather than A is:

where:

• ΔΠ_B-A = change in profit from selecting B rather than A, in currency;
• R_A and R_B = future revenues under alternatives A and B;
• C_A and C_B = future relevant costs under alternatives A and B.

If ΔΠ_B-A > 0, B is financially preferable. The relationship assumes that all material differential revenues, costs, and opportunity costs have been measured consistently over the same period.

1.2 Classification of decision costs

These classifications overlap. For example, an avoidable salary is also a future differential cost. However, not every future cost is avoidable.

1.3 Sunk costs versus committed costs

A sunk cost has already been incurred. The historical purchase price or existing book value of a machine is usually sunk when considering its replacement.

A committed cost is associated with a binding future obligation, such as a non-cancellable lease payment due next year. If it cannot be changed by any feasible alternative, it is unavoidable and irrelevant to the immediate decision. It should not be called sunk because it has not yet been incurred. If the contract can be cancelled, transferred, or renegotiated, the avoidable portion may be relevant.

1.4 Opportunity costs and capacity

Opportunity cost is the contribution or other benefit sacrificed when a scarce resource is used in one way rather than its best available alternative. It normally does not appear in the accounting ledger.

If idle capacity has no alternative use, its opportunity cost may be zero. If accepting an order displaces regular sales, the lost contribution margin is relevant.

Only feasible alternatives count. Speculative uses of capacity should not be treated as certain opportunity costs.

1.5 Contribution margin and limiting factors

Contribution margin is revenue less variable costs:

When one resource constrains output, products should generally be compared using contribution per unit of the limiting factor:

This ranking rule applies when products can be produced and sold in divisible quantities, the stated contribution margins are valid, and a single limiting factor dominates. Multiple constraints, indivisibilities, minimum commitments, or interdependent demand may require linear or integer programming.

2. A Structured Decision Process

A defensible relevant-cost analysis follows a disciplined sequence.

Figure: A structured process for short-term relevant-cost decisions.

The analyst should use consistent units and time periods, document assumptions, and avoid including an item merely because it appears in the accounting system. A common-cost allocation should be replaced by an estimate of the actual cash flow that changes.

3. Make-or-Buy and Outsourcing Decisions

A make-or-buy decision compares internal production with external procurement. Outsourcing is broader and may involve transferring an activity, personnel, technology, or responsibility to an external organization.

3.1 Relevant financial elements

The relevant cost of making can include:

• direct materials and labor that will be avoided if purchasing;
• variable overhead;
• avoidable fixed supervision or equipment costs;
• opportunity cost of capacity used internally;
• incremental quality, logistics, or compliance costs.

The relevant cost of buying can include:

• supplier price;
• freight, insurance, tariffs, and inspection;
• contract administration;
• transition costs;
• internal costs that remain despite outsourcing.

Allocated fixed manufacturing overhead is not automatically avoidable.

3.2 Worked example: make or buy

A business requires 10,000 components. Unit production costs are:

Of the fixed overhead, $40,000 would be avoided if the component were purchased. A supplier offers the component for $18 per unit. Internal production also prevents another use of the facility that would generate $15,000 contribution.

Relevant cost of making:

Relevant cost of buying:

Buying produces a financial advantage of:

The remaining $20,000 of allocated fixed overhead is irrelevant because it continues under either alternative. Before buying, management must evaluate supplier quality, intellectual-property protection, lead times, labor consequences, exchange-rate exposure, and supply continuity.

3.3 Indifference price

The maximum acceptable supplier price per unit can be derived by equating relevant make and buy costs. If Q is quantity, C_M is total relevant make cost excluding any supplier payment, and C_B is other incremental buying cost, then:

This formula assumes the quantity and other relevant consequences remain unchanged across the price comparison.

4. Special-Order Decisions

A special order is a non-routine sale, often at a price below the normal list price. A low price may still increase profit when idle capacity exists and the price exceeds incremental cost.

For an order that does not affect regular business:

If regular sales are displaced, lost contribution must also be deducted:

Worked example: idle capacity

A company receives an order for 5,000 units at $14 each. Variable manufacturing cost is $9 per unit, special packaging costs $1 per unit, and a one-time setup costs $12,000. The order uses idle capacity and does not affect regular sales.

Financially, the order should be accepted. However, management should consider whether regular customers could demand the same price, whether resale can be restricted, and whether the order breaches competition law, export controls, or contractual territories.

5. Temporary Shutdown and Closure Decisions

A temporary shutdown differs from permanent abandonment. During shutdown, some fixed costs may continue, while shutdown, maintenance, security, and restart costs may arise.

Let:

• CM_L = contribution margin lost during shutdown;
• F_A = fixed costs avoided by shutting down;
• I_A = income from an alternative use of resources;
• C_S = shutdown and restart costs.

The incremental profit effect of shutting down rather than continuing is:

A positive result favors shutdown; a negative result favors continued operation. This formulation assumes unchanged fixed costs have been excluded.

Worked example: seasonal shutdown

A facility would earn $100,000 contribution margin if it remained open. Shutdown would avoid $62,000 of fixed costs and permit temporary rental income of $25,000. Shutdown and restart would cost $4,000.

Shutdown would reduce profit by $17,000, so remaining open is financially preferable. Management should also consider employee retention, customer migration, equipment deterioration, safety, and the probability that reopening will be delayed.

Permanent closure requires a longer horizon and may include severance, asset disposal, environmental remediation, contract termination, and loss of strategic options.

6. Equipment Replacement Decisions

Replacement analysis is frequently distorted by the old asset's book value. Book value is a past accounting amount and is not itself a future cash flow. Relevant items may include:

• purchase and installation cost of the new asset;
• proceeds from selling the old asset now;
• changes in operating and maintenance cash flows;
• changes in working capital;
• differential disposal value at the end of the horizon;
• tax effects, where applicable.

The current disposal value of the old asset is relevant because retaining it sacrifices the opportunity to sell it.

Where time value is material, replacement should be evaluated using differential net present value:

where:

• I₀ = initial cost of the replacement asset;
• P₀ = proceeds from disposing of the old asset now;
• S_t = net operating cash savings in period t;
• TV_n = differential terminal value at the end of period n;
• r = discount rate per period;
• n = number of periods.

All amounts must be incremental and measured on a consistent after-tax or pre-tax basis. Tax depreciation can make accounting book value indirectly relevant through its effect on taxable gain, loss, or future tax deductions.

Worked example: replacement NPV

A new machine costs $120,000 and will save $35,000 annually for four years. The existing machine can be sold now for $15,000. At the end of year 4, the new machine will have an $8,000 greater disposal value than the old machine. Using an 8% annual discount rate and ignoring taxes, the four-year annuity factor is 3.3121 and the year-4 discount factor is 0.7350.

The positive NPV supports replacement, subject to operating reliability and estimation risk.

7. Sell-or-Process-Further Decisions

Joint products emerge from a common process up to a split-off point. Joint costs incurred before split-off cannot be changed by a subsequent processing decision and are therefore irrelevant to whether one product should be processed further.

The decision rule is:

Further processing is financially desirable if the incremental gain is positive, assuming sufficient capacity and no adverse effect on other products.

Worked example

Ten thousand units can be sold at split-off for $12 each or processed further and sold for $17 each. Additional processing costs $38,000.

The product should be processed further. Joint costs incurred before split-off do not affect this conclusion. If further processing consumes constrained capacity, the contribution sacrificed elsewhere must be included.

8. Risk, Uncertainty, and Sensitivity

Relevant-cost estimates are rarely certain. Demand, defect rates, exchange rates, energy prices, supplier performance, and restart times may vary.

8.1 Expected-value analysis

For mutually exclusive outcomes with probabilities summing to 1:

where p_i is the probability of outcome i and ΔΠ_i is its differential profit. Expected value is most informative for repeated decisions or risk-neutral evaluation; it does not show the range of outcomes or the severity of downside exposure.

8.2 Sensitivity and break-even analysis

Sensitivity analysis changes one assumption at a time to identify decision-critical variables. Scenario analysis changes several related assumptions together. Useful break-even questions include:

• At what supplier price does make equal buy?
• What minimum special-order price covers all incremental consequences?
• How many periods of operating savings justify replacement?
• How much avoidable fixed cost is required to justify shutdown?

Managers should pay particular attention to assumptions that are both uncertain and capable of reversing the decision.

8.3 Decision limitations

Relevant-cost analysis may be limited by:

• inaccurate cost behavior assumptions;
• nonlinear costs or quantity discounts;
• uncertain capacity and demand;
• shared resources with difficult-to-measure opportunity costs;
• strategic effects extending beyond the nominal short term;
• behavioral bias, including escalation of commitment to sunk investments;
• inconsistent treatment of inflation, tax, and discounting.

9. Illustrative Case: Meridian Controls Ltd.

Background

Meridian Controls Ltd. is a fictional manufacturer of electronic control modules. It requires 12,000 circuit assemblies for next year's production. Management is considering outsourcing the assemblies to a specialist supplier.

Internal production incurs variable costs of $42 per assembly. A production supervisor's $72,000 salary would be avoided if outsourcing occurs. Other allocated factory costs of $108,000 would continue. Each assembly uses 0.5 hour of a constrained testing facility.

The supplier quotes $51 per assembly. Incoming inspection would cost Meridian $1 per purchased assembly. Outsourcing would release 6,000 testing hours. Meridian can use only 5,000 of those hours for another product, earning contribution of $22 per testing hour; the remaining 1,000 hours have no alternative use.

Problem

Should Meridian manufacture or outsource the assemblies, and what nonfinancial issues should affect the decision?

Analysis

Relevant cost of making:

The $108,000 allocated factory cost is excluded because it will continue.

Relevant cost of outsourcing:

Outsourcing provides an estimated advantage of:

The supplier-price threshold is obtained from:

Thus, the quoted price of $51 is about $5.17 per assembly below the financial indifference price.

Approach and solution

The financial evidence supports outsourcing. However, Meridian should conduct supplier audits, test product samples, assess cybersecurity and intellectual-property controls, examine financial stability, and negotiate service-level, traceability, warranty, and continuity provisions. A phased contract or dual-sourcing arrangement may reduce disruption risk.

Outcome

Assuming the supplier satisfies technical and ethical due diligence, Meridian should outsource and redirect 5,000 testing hours to the higher-contribution product. Management should monitor defect rates, total landed cost, delivery reliability, and realized opportunity benefits.

Learning points

1. Continuing allocated fixed costs should not be treated as savings.
2. Only 5,000 of the 6,000 released hours have an opportunity value.
3. The lowest quoted supplier price is not necessarily the lowest total relevant cost.
4. Sensitivity thresholds clarify how much adverse change the recommendation can withstand.
5. Contract design and supplier governance are integral to the decision.

10. Qualitative, Ethical, and Governance Considerations

A financially favorable alternative may be unacceptable after considering wider consequences.

10.1 Quality and customer effects

Special orders or outsourced inputs may affect defects, warranties, delivery reliability, brand reputation, and regular customer relationships. These effects should be quantified where credible, but unsupported precision should be avoided.

10.2 Employees and communities

Outsourcing and shutdown decisions may cause layoffs or income insecurity. Managers should comply with employment law, consultation requirements, collective agreements, and severance obligations. Ethical practice also requires transparent communication and avoidance of misleading assurances.

10.3 Supplier and environmental governance

Due diligence should examine labor standards, modern slavery risk, bribery, environmental compliance, data security, and supply-chain resilience. A cheap supplier may create substantial contingent costs or reputational exposure.

10.4 Manipulation and conflicts of interest

Managers may selectively classify costs to protect departments, justify prior investments, or achieve bonuses. Governance controls should require documented assumptions, independent review, conflict declarations, and post-decision evaluation. Sunk costs must not be retained merely to avoid admitting a past mistake.

10.5 Strategic coherence

Short-term savings can erode long-term capabilities. Repeated outsourcing may weaken technical knowledge, bargaining power, innovation, or emergency capacity. Conversely, internal production retained for emotional reasons can consume resources better deployed elsewhere.

11. Technology and Contemporary Practice

Enterprise resource planning systems can extract transaction-level cost data, while activity-based costing can improve estimates of avoidable support costs. Advanced analytics can model capacity use, supplier risk, and alternative scenarios. Digital twins and process-mining tools may reveal bottlenecks and operational interdependencies.

Artificial intelligence can assist by forecasting demand, detecting unusual cost patterns, or generating scenarios. However, AI outputs depend on historical data and model assumptions. Human review remains necessary to prevent hidden bias, double counting, privacy breaches, and unsupported causal conclusions. Decision models should preserve an audit trail showing data sources, assumptions, approvals, and subsequent performance.

12. Professional Best Practices

Sound relevant-cost analysis should:

1. Define the decision, horizon, and feasible alternatives clearly.
2. Reconcile managerial data with accounting records without importing irrelevant allocations.
3. Separate cash-flow effects, opportunity costs, and qualitative consequences.
4. State capacity, demand, tax, inflation, and timing assumptions.
5. Use sensitivity or scenario analysis for material uncertainties.
6. Obtain operational, legal, procurement, human-resource, and sustainability input.
7. Document why significant items were included or excluded.
8. Monitor actual results and update future decision models.

Chapter Summary

Relevant costing identifies future revenues and costs that differ between feasible alternatives. Incremental and avoidable costs are generally relevant, whereas sunk costs and unchanged future costs are not. Opportunity costs capture the benefits sacrificed when scarce resources are committed to one use rather than another.

Make-or-buy analysis compares avoidable internal costs and capacity effects with the total landed cost and risks of purchasing. Special orders should be evaluated using incremental revenue, incremental cost, and any contribution displaced. Shutdown decisions compare avoided costs and alternative income with lost contribution and shutdown or restart costs. Replacement decisions focus on future cash flows, disposal opportunities, operating savings, terminal values, taxes, and, where material, discounting. Sell-or-process-further decisions exclude joint costs incurred before split-off and compare incremental revenue with additional processing cost.

Quantitative analysis should be supplemented by sensitivity testing, strategic judgment, ethical reasoning, stakeholder assessment, and governance controls. The objective is not merely to select the lowest visible accounting cost, but to identify the alternative that creates the greatest sustainable benefit within legal and ethical constraints.

Key Terms

Relevant cost: A future cost that differs between feasible alternatives.

Incremental cost: Additional cost resulting from a particular action.

Differential cost: Difference in cost between two alternatives.

Avoidable cost: Cost eliminated when an activity or alternative is discontinued.

Unavoidable cost: Cost that continues regardless of the selected alternative.

Sunk cost: Cost already incurred and not recoverable through the current decision.

Committed cost: Future cost arising from an existing obligation.

Opportunity cost: Benefit sacrificed by rejecting the best feasible alternative.

Contribution margin: Sales revenue less variable costs.

Allocated fixed cost: Portion of a common fixed cost assigned to a cost object.

Relevant range: Activity interval within which stated cost-behavior assumptions hold.

Limiting factor: Scarce resource that restricts output or sales.

Make-or-buy decision: Choice between internal production and external purchase.

Special order: Non-routine customer order requiring incremental analysis.

Shutdown decision: Choice between temporary suspension and continued operation.

Split-off point: Stage in joint production at which separate products become identifiable.

Net present value: Present value of incremental future cash inflows less outflows.

Sensitivity analysis: Examination of how a decision changes when an assumption changes.

Review Questions

Short Answer Questions

1. What two conditions must a cost satisfy to be relevant?
2. Why is the book value of an existing machine usually irrelevant to replacement?
3. Distinguish a sunk cost from an unavoidable committed cost.
4. When does released capacity create an opportunity cost?
5. Why are joint costs excluded from a sell-or-process-further decision?

Long Answer Questions

1. Explain how allocated fixed overhead can distort a make-or-buy analysis.
2. Discuss the financial and qualitative considerations relevant to outsourcing.
3. Develop a framework for evaluating a special order when production is at full capacity.
4. Explain how temporary shutdown analysis differs from permanent closure analysis.
5. Discuss how risk, ethics, governance, and strategy can change a recommendation based solely on relevant costs.

Analytical / Application Questions

1. A component has avoidable internal costs of $24 per unit and uses capacity that could earn $6 contribution per unit. A supplier offers a price of $28 plus $1 freight. Analyze the decision and identify two qualitative considerations.
2. A special order for 2,000 units offers $19 per unit. Incremental production and delivery costs are $14 per unit, but the order would displace 500 regular units earning contribution of $12 each. Calculate the incremental profit and recommend an action.
3. A product can be sold at split-off for $90,000 or processed further and sold for $128,000. Further processing costs $31,000 and uses capacity with an opportunity cost of $9,000. Determine whether further processing is financially desirable.

Multiple Choice Questions with Answers

Question 1

Which statement best defines a relevant cost?

A. Any cost allocated to the product under absorption costing

B. A future cost that differs between feasible alternatives

C. Any cost that has already been recorded in the ledger

D. A fixed cost that cannot be avoided

Correct Answer: B. A future cost that differs between feasible alternatives

Question 2

A component requires variable manufacturing cost of $14 per unit and avoidable fixed cost of $30,000 for 5,000 units. Producing it also sacrifices contribution of $10,000. A supplier offers the component for $20 per unit with no other purchasing costs. What is the financial effect of buying rather than making?

A. Buying saves $10,000

B. Buying saves $20,000

C. Making saves $10,000

D. The alternatives have equal relevant cost

Correct Answer: A. Buying saves $10,000

Question 3

A special order requests 3,000 units at $16 each. Variable production cost is $11 per unit, special delivery costs $2 per unit, and one-time setup costs are $6,000. Idle capacity is available. What is the order's incremental profit?

A. $3,000

B. $6,000

C. $9,000

D. $15,000

Correct Answer: A. $3,000

Question 4

A factory has idle space with no feasible alternative use. What is the opportunity cost of using that space for a special order?

A. Its allocated depreciation

B. Its historical construction cost

C. Zero

D. Its full absorption cost

Correct Answer: C. Zero

Question 5

A temporary shutdown would avoid $62,000 of fixed costs, generate $25,000 of alternative income, sacrifice $100,000 of contribution margin, and incur $4,000 of shutdown and restart costs. What is the profit effect of shutdown relative to continuing?

A. A $17,000 increase

B. A $17,000 decrease

C. A $13,000 decrease

D. A $21,000 increase

Correct Answer: B. A $17,000 decrease

Question 6

Which item is ordinarily irrelevant when evaluating replacement of an existing machine, assuming no tax consequences?

A. The machine's current disposal value

B. Future maintenance cost of the machine

C. The machine's current book value

D. Purchase and installation cost of the replacement

Correct Answer: C. The machine's current book value

Question 7

A joint product can be sold at split-off for $80,000 or processed further and sold for $115,000. Further processing costs $29,000. What is the incremental financial effect of further processing?

A. A $6,000 gain

B. A $29,000 gain

C. A $35,000 gain

D. A $6,000 loss

Correct Answer: A. A $6,000 gain

Question 8

Product X earns contribution of $48 per unit and requires 3 machine hours. Product Y earns contribution of $35 per unit and requires 2 machine hours. If machine hours are the only constraint and all output can be sold, which product receives priority?

A. Product X because its unit contribution is higher

B. Product Y because its contribution is $17.50 per machine hour

C. Product X because its contribution is $16 per machine hour

D. Neither product because fixed cost information is missing

Correct Answer: B. Product Y because its contribution is $17.50 per machine hour

Question 9

An alternative produces a $40,000 gain with probability 0.70 and a $20,000 loss with probability 0.30. What is its expected differential profit?

A. $14,000

B. $20,000

C. $22,000

D. $28,000

Correct Answer: C. $22,000

Question 10

Which practice provides the strongest governance over a major outsourcing decision?

A. Accepting the lowest quoted price without further review

B. Including all allocated overhead as an avoidable saving

C. Relying solely on an AI-generated recommendation

D. Documenting assumptions, conducting supplier due diligence, and monitoring outcomes

Correct Answer: D. Documenting assumptions, conducting supplier due diligence, and monitoring outcomes