CB2101 Chap.1 Cost Concepts and Managerial Decisions
Cost Concepts and Managerial Decisions
Choose the classification axis first
A cost can be classified by manufacturing function, behaviour, traceability or relevance. These labels are not substitutes. The same supervisor salary may be direct to a department, indirect to a product, fixed within a relevant range and avoidable only if a future decision removes the position.
Strong answers name the cost object and decision before applying a label.
Follow manufacturing cost into inventory
Direct materials, direct labour and manufacturing overhead enter work in process. Completion moves cost to finished goods, and sale moves it to cost of goods sold. Selling and administrative resources remain period costs.
This flow gives a practical check: if unsold production has been expensed immediately, or a marketing cost has entered inventory, revisit the functional classification before accepting the total.
Keep behaviour inside the relevant range
Variable cost is stable per activity unit and changes in total, while fixed cost is stable in total and changes per unit as volume moves.
Those patterns hold only over the activity range and time horizon in the facts. A capacity step, contract renewal or overtime band can change the relationship. State the range rather than treating fixed and variable as permanent physical properties.
Make traceability depend on the object
A resource is direct when it can be economically traced to the chosen cost object.
A factory manager is direct to the factory and indirect to one product; dedicated equipment can be direct to a line and fixed with respect to its units. This is why direct does not mean variable and indirect does not mean fixed. Write the cost object beside each classification so the reader can test it.
Filter decision information last
Relevant costs are future differences between alternatives.
Past acquisition cost is sunk, an unchanged allocation is irrelevant, and a benefit sacrificed by committing capacity is an opportunity cost even though it never appears in the ledger. Show excluded amounts with a reason.
That visible filter demonstrates that every figure was considered and prevents a complete accounting statement from being mistaken for a decision analysis.
Use a contribution format for internal questions
Separating variable expenses from fixed expenses reveals contribution margin, the amount available to cover fixed resources and profit.
The format supports CVP and short-run choices, but it does not decide relevance by itself. A fixed lease that can be cancelled may be relevant, while a variable amount already incurred is not. Behaviour informs the forecast; alternatives determine inclusion.
What this chapter covers
- 01
Manufacturing and nonmanufacturing costs
- 02
Product and period cost flows
- 03
Variable and fixed behaviour
- 04
Direct and indirect traceability
- 05
Relevant, sunk and opportunity costs
- 06
Contribution-format statements
Worked example · free
Filter costs for a make-or-buy decision
- 2Identify future cash flows that change.
- 2Exclude sunk or continuing amounts.
- 2State the capacity assumption.
Key terms
- Cost Object
- The product, service, customer or activity for which cost is measured.
- Product Cost
- A manufacturing cost attached to inventory until the related product is sold.
- Sunk Cost
- A past cost that cannot be changed by the current decision.
Cost Concepts and Managerial Decisions FAQ
Why can one cost have several labels?
Each label answers a different question. Function determines inventory treatment, behaviour describes response to activity, traceability depends on the chosen cost object, and relevance depends on future alternatives. State the question before applying the label.
Are fixed costs always irrelevant?
No. A future fixed commitment that disappears under one alternative is relevant, while a variable amount already incurred is sunk. Cost behaviour does not decide relevance; the decision changes and timing do.
How can I check a manufacturing cost flow?
Trace materials, labour and overhead into work in process, then finished goods, then cost of goods sold when units are sold. Selling and administrative costs remain period expenses rather than entering inventory.
What is the fastest way to test relevance?
Write the two alternatives in columns and ask whether each future cash flow changes. Exclude sunk amounts and allocations that continue, then add any contribution sacrificed by using constrained capacity. Label the time horizon because a fixed commitment may be unavoidable now but avoidable at renewal. Finish by naming the assumption that would make an excluded amount change.
Exam move
Create a four-column card for each example cost: function, behaviour, traceability and decision relevance. Change the cost object or alternative and explain which labels move. Next, draw the manufacturing inventory flow and place each cost into work in process, finished goods, cost of goods sold or period expense.
Rework one mixed-cost case in totals and per-unit terms so that fixed-cost averaging cannot masquerade as variable behaviour. For every decision example, cross out sunk and unchanged amounts, then add any opportunity cost from displaced capacity. Keep an error log organised by classification axis rather than question number.
Before a quiz, take five unfamiliar costs and state the cost object, relevant range and alternative aloud. Finish by rebuilding a contribution-format statement and explaining why behaviour information supports forecasting but does not, by itself, determine relevance.
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