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Cost Classification for Decision Making and Control in ACCA Management Accounting

Updated 11 October 2026 · Fact-checked

Cost classification for decision making groups costs by how useful they are for a choice or for control. Relevant costs are future, cash and differ between options. Sunk costs are already spent and ignored. Opportunity costs are lost benefits. Controllable costs can be influenced by a manager. Cost centres and cost units collect and measure costs.

Understand Cost Classification for Decision Making and Control

Managers use costs for two jobs. The first is decision making: choosing between options. The second is control: checking that people spend as planned. Different classifications serve each job.

For decisions, ask one question: will this cost change because of the decision? A relevant cost is a future cash flow that differs between the options. A sunk cost has already been incurred, so no decision can change it. Ignore it. An opportunity cost is the benefit you give up by choosing one option over the next best use of a resource. It is relevant even though no cash is paid. An avoidable cost is one that would not be incurred if you stopped an activity. It is relevant to a closure decision. An unavoidable cost continues either way.

For control, ask: who can influence this cost? A controllable cost is one a manager can influence through their own decisions in the period. An uncontrollable cost cannot be influenced by that manager, such as a head office charge allocated to a branch. The same cost can be controllable at one level and uncontrollable at another. A factory manager may not control the rent, but the board does.

To collect costs, organisations use cost units and cost centres. A cost unit is the unit of product or service you measure cost for, such as a litre of paint, a patient-day or a passenger-kilometre. A cost centre is a location, function or item of equipment for which costs are collected, such as a canteen or a machine shop. Cost centres only collect costs.

Responsibility centres go further. A profit centre is responsible for both costs and revenues. An investment centre is responsible for costs, revenues and the assets used, so it is judged on return on investment or residual income.

Key formulas to remember

Relevant cost test: Relevant = future + cash flow + differs between options; All three conditions must hold. Fail any one and the cost is not relevant.
Opportunity cost of using a resource: Opportunity cost = contribution or benefit lost from the next best use; Include it in addition to any extra cash cost of using the resource.
Relevant cost of materials already in inventory: If no other use: scrap or resale value. If it would be replaced: replacement cost; The original purchase price is sunk and is never used.
Closure decision: Keep if avoidable revenue lost > avoidable costs saved; Ignore unavoidable costs such as apportioned head office costs.
Responsibility centre scope: Cost centre: costs. Profit centre: costs + revenues. Investment centre: costs + revenues + assets; Revenue centres are responsible for revenue only.

How to solve Cost Classification for Decision Making and Control questions

Use this method for any question that asks you to classify a cost or choose the relevant figure.

1Read the scenario and identify the decision or the control purpose being asked about.
2List every cost or figure given.
3Remove sunk costs: anything already spent or committed that cannot be changed.
4Remove costs that are the same under all options, and non-cash items such as depreciation and apportioned overheads.
5Add opportunity costs for resources that have a better alternative use.
6For control questions, ask who can influence the cost at that level of management. If nobody there can, it is uncontrollable for them.
7Check the wording of the options and pick the one that matches your classification exactly.

Quickest way: Three-question filter

When to use it: Use it on multiple choice questions where several costs are listed and you must pick the relevant or controllable one.

Ask: is it in the future? If not, it is sunk. Reject it.
Ask: does it differ between the options? If not, reject it.
Ask: is it a cash flow or a lost benefit? If it is only an accounting allocation, reject it.
For control wording, replace these with one question: can this manager change it?
Pick the remaining option. If a resource is already owned, check for an opportunity cost.

Common mistakes in Cost Classification for Decision Making and Control

Including the original cost of inventory already bought as a relevant cost.
The figure is given in the question, so it feels important.
Fix: It is sunk. Use resale value or replacement cost, depending on whether the material would be replaced.
Treating depreciation and apportioned overheads as relevant.
They appear in the cost schedule and look like costs of the project.
Fix: They are non-cash or unchanged by the decision. Only include extra cash costs caused by the decision.
Forgetting opportunity cost when no cash is paid.
Students think a cost needs a payment.
Fix: If using a resource stops it earning elsewhere, the lost benefit is a relevant cost.
Calling a cost uncontrollable because it is fixed.
Fixed and uncontrollable are mixed up.
Fix: Controllability depends on the manager's authority, not on cost behaviour. A manager can control a fixed cost they can decide to change.
Confusing a cost centre with a cost unit.
Both words are used to describe where costs go.
Fix: A cost centre is a place or function that collects costs. A cost unit is the item you measure cost per.
Saying a profit centre is judged on assets used.
Profit and investment centres are blurred.
Fix: Only an investment centre is responsible for assets and judged on return on investment or residual income.

Worked examples

Example 1

A company is deciding whether to accept a special order. It needs 500 kg of material X. It already holds 500 kg bought for $4 per kg. The material has no other use and could be sold for $1.50 per kg. Replacement would cost $5 per kg. What is the relevant cost of the material for the order?

Show the solution

The original price of $4 per kg is sunk. Ignore it.
The material has no other use, so it would not be replaced.
The alternative is to sell it, so the opportunity cost is the resale value of $1.50 per kg.
Relevant cost = 500 × $1.50 = $750.

Answer: $750

Example 2

Division P, a profit centre, is charged $60,000 of head office costs it cannot influence. Its manager controls staff costs of $90,000 and materials of $120,000. Revenue is $400,000. What is the profit based on controllable costs only?

Show the solution

Controllable costs are those the manager can influence: staff and materials.
Total controllable costs = $90,000 + $120,000 = $210,000.
The head office charge of $60,000 is uncontrollable, so exclude it.
Controllable profit = $400,000 − $210,000 = $190,000.

Answer: $190,000

Exam tips

In multiple choice, cross out sunk costs first. This usually removes one or two options at once.
For number entry on relevant costs, write each figure and mark it keep or drop before adding. Do not guess the total.
Read the word carefully: relevant, avoidable, controllable and opportunity cost are tested with similar wording but have different meanings.
Know the three responsibility centres by what they control: costs, costs and revenues, or costs, revenues and assets.
Where a question gives cost units, think about what suits the business: manufacturers use products, hospitals use patient-days, transport firms use passenger-kilometres.

Practice questions from Cost classification

Cost Classification for Decision Making and Control in other exams

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

Cost Classification for Decision Making and Control: frequently asked questions

What is the difference between controllable and uncontrollable costs?

A controllable cost is one a manager can influence through their own decisions in the period. An uncontrollable cost is outside their authority, such as an allocated head office charge. The same cost can be controllable at a higher level of management.

What is the difference between a sunk cost and an opportunity cost?

A sunk cost has already been spent and cannot be changed, so it is ignored in decisions. An opportunity cost is the benefit lost by using a resource in one way rather than its best alternative. Opportunity costs are relevant, sunk costs are not.

What is a cost centre and a cost unit?

A cost centre is a location, function or item of equipment where costs are collected, such as a maintenance department. A cost unit is the unit of output you measure cost for, such as a unit of product or a patient-day.

How do profit centres and investment centres differ?

A profit centre manager is responsible for costs and revenues. An investment centre manager is also responsible for the assets used. This is why investment centres are judged on measures such as return on investment or residual income.