Strategic Cost Management · Relevant Cost Analysis

Relevant Cost Concepts and Decision Making for CMA Final

Updated 11 October 2026 · Fact-checked

A relevant cost is a future cost that differs between the alternatives you are comparing. To solve a question, list each alternative, keep only future, avoidable, differing cash items, include opportunity costs, drop sunk and committed costs, compare the incremental figures, and recommend the better option.

Understand Relevant Cost Concepts and Decision Making

Every short-term decision compares alternatives. Make or buy, accept or reject an order, continue or shut down: each one asks what changes if you choose A instead of B. Only the things that change matter. That is the whole idea of relevant costing.

A cost is relevant when it meets three tests. It is a future cost. It is a cash (or cash-equivalent) cost caused by the decision. It differs between alternatives. Anything failing a test is irrelevant and should be ignored, even if it looks large.

Incremental (differential) cost is the extra cost of choosing one alternative over another. Opportunity cost is the benefit you give up by using a resource in one way instead of its best alternative use. It is relevant, even though no cash is paid out. For example, if a machine used for a special order could otherwise be hired out for ₹40,000, that ₹40,000 is a cost of the order.

Sunk cost is already spent and cannot be recovered whatever you decide, such as money paid earlier for market research or the book value of an old machine. It is irrelevant. Committed cost is a future cost you are already legally or contractually bound to pay, such as rent under a lease you cannot exit. It is irrelevant too, because it is the same under every alternative. Also ignore non-cash items such as depreciation on existing assets, and allocated fixed overheads that will not change.

The framework is simple. Identify the alternatives, strip out irrelevant items, add opportunity costs, compare the incremental revenue with the incremental cost, and also weigh qualitative factors such as quality, supplier reliability and customer relations. The answer is a recommendation, not just a number.

Key rules to remember

Relevant cost of a decision: Relevant cost = Future incremental cash cost + Opportunity cost; Use only costs that change because of the decision.
Opportunity cost of a resource: Opportunity cost = Contribution or benefit lost from the best alternative use; Applies when the resource is scarce or already in use. If it is in surplus with no other use, it is nil.
Relevant cost of material: Material in regular use: current replacement cost. Material in stock, not needed again: higher of resale value and cost of alternative use (else nil). Material in stock needed again: replacement cost.; Historical cost is never relevant by itself.
Relevant cost of labour: Spare capacity: nil extra cost if wages are fixed. Fully utilised: wages paid + contribution lost elsewhere; Extra labour hired is charged at its additional pay.
Incremental analysis: Incremental profit = Incremental revenue − Incremental (relevant) cost; Accept the alternative with positive and higher incremental profit.

How to solve Relevant Cost Concepts and Decision Making questions

Use this method for any relevant cost question, whether it asks for a decision or for the relevant cost of an item.

1List the alternatives clearly, including doing nothing.
2Go through every cost given and mark it future or past. Cross out sunk costs.
3Cross out committed costs and costs that stay the same in every alternative, including non-cash items such as depreciation and unchanged allocated overheads.
4For each resource used, ask whether it is scarce or in surplus. Add opportunity cost for scarce resources, and use replacement cost or resale value for materials as the case requires.
5Compute incremental revenue and incremental relevant cost for each alternative, and take the difference.
6State the decision in one sentence, for example accept the order because it adds ₹X to profit.
7Add short qualitative points and any condition under which your answer would change.

Quickest way: Three-test filter and incremental table

When to use it: Use it when time is short and the question gives many cost figures, some of them traps.

Next to each figure write F (future), C (cash) and D (differs). Keep a cost only if all three are yes.
Write one line for each retained item: revenue, then relevant costs, then opportunity cost.
Subtract to get net benefit and write the recommendation immediately.
Spend the last minute listing the dropped costs with a reason such as sunk or committed. Examiners give marks for this.

Common mistakes in Relevant Cost Concepts and Decision Making

Using the book value or historical cost of stock materials as the relevant cost.
The figure is given in the question and looks like a cost of the job.
Fix: Ask what the firm will actually give up or pay now: replacement cost, resale value or alternative use value.
Treating allocated fixed overheads as relevant.
Students use a full absorption rate per unit automatically.
Fix: Include fixed cost only if it will actually increase or be avoided because of the decision.
Ignoring opportunity cost because no cash is paid.
Students equate cost with cash outflow.
Fix: If a resource has a better alternative use, charge the contribution lost from it.
Including depreciation of existing assets.
Depreciation appears in the cost sheet, so it feels like a cost.
Fix: It is non-cash and based on past outlay, so exclude it unless the decision changes asset use that creates a real cash effect.
Treating a committed cost as avoidable.
Students see a cost linked to the product and assume it stops if the product stops.
Fix: Check whether a contract or law forces payment either way. If so, it is irrelevant.
Giving only a number and no recommendation.
Students stop once the calculation is done.
Fix: Always end with a decision and mention qualitative factors.

Worked examples

Example 1

Surya Engineering is asked to make a special order needing 500 kg of material X. It holds 500 kg in stock bought at ₹120 per kg. The material has no other use and could be sold for ₹85 per kg. Its current replacement price is ₹140 per kg. The customer offers ₹1,00,000 for the order, and other relevant costs excluding material are ₹30,000. Should the order be accepted?

Show the solution

The ₹120 purchase price is historical and irrelevant.
The stock has no other use, so the relevant cost is the resale value forgone: 500 × ₹85 = ₹42,500. Replacement cost does not apply because the material will not be bought again.
Relevant costs = ₹42,500 + ₹30,000 = ₹72,500.
Incremental profit = ₹1,00,000 − ₹72,500 = ₹27,500.

Answer: Accept the order. It adds ₹27,500 to profit. The ₹60,000 original cost of the stock (500 × ₹120) is sunk and was ignored.

Example 2

Kaveri Ltd can use 2,000 machine hours either for a special job or for its regular product. The special job offers revenue of ₹6,00,000. Its direct material is ₹2,00,000 and direct labour is ₹1,50,000 (both extra cash costs). Using the same hours on the regular product would earn a contribution of ₹90,000. Fixed overhead absorbed on the job at ₹50 per machine hour is ₹1,00,000, but total fixed overhead will not change. Should the firm take the special job?

Show the solution

Fixed overhead of ₹1,00,000 is unchanged in total, so it is irrelevant.
Relevant cash costs = material ₹2,00,000 + labour ₹1,50,000 = ₹3,50,000.
Opportunity cost = contribution lost on the regular product = ₹90,000.
Total relevant cost = ₹3,50,000 + ₹90,000 = ₹4,40,000.
Net benefit = ₹6,00,000 − ₹4,40,000 = ₹1,60,000.

Answer: Take the special job. It gives ₹1,60,000 more than the best alternative use of the machine hours.

Exam tips

In MCQs, scan for the trap: sunk cost, committed cost, absorbed fixed overhead or depreciation. The correct option usually excludes it.
In written answers, show a short table of items included and excluded with a one-word reason. This earns method marks even if a figure is wrong.
For materials, read carefully whether the stock will be replaced. The answer changes between replacement cost, resale value and nil.
For labour, check whether workers are on fixed pay with idle time or fully occupied. Opportunity cost applies only in the second case.
Close every answer with a clear recommendation and one or two qualitative factors.

Practice questions from Relevant Cost Analysis

Relevant Cost Concepts and Decision Making in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Relevant Cost Concepts and Decision Making: frequently asked questions

What is the difference between relevant and irrelevant cost?

A relevant cost is a future cost that differs between alternatives. An irrelevant cost is one that is already incurred, committed or the same under every option. Only relevant costs should influence the decision.

What is the difference between opportunity cost and sunk cost?

Opportunity cost is the benefit lost by not using a resource in its best alternative way, and it is relevant. Sunk cost is money already spent that cannot be recovered, and it is irrelevant. For example, the price paid for an old machine is sunk, but the rent you could earn by hiring it out is an opportunity cost.

Is a committed cost always irrelevant?

It is irrelevant when it must be paid under every alternative. If a decision gives you a real way to avoid or change the commitment, only the avoidable part is relevant. Read the facts of the question to see what can actually be avoided.

Is depreciation a relevant cost?

Normally no. Depreciation on an existing asset is a non-cash allocation of a past cost. It may matter only if the decision changes a real cash flow, such as a fall in the asset's resale value because of extra use.