Cost Accounting Fundamentals and Cost Classification
Cost accounting fundamentals and cost classification is the domain that tests whether you can define a cost object, trace costs to it, and classify costs for inventory valuation, decision-making and control. ICSAN questions often ask you to separate prime cost from overhead and to explain why the same cost can be direct in one setting and indirect in another.
Core rules and concepts
- A cost object is anything for which separate cost measurement is required; a cost unit is the unit of output used, such as a patient-day or a batch.
- Prime cost = direct materials + direct labour + direct expenses. Conversion cost = direct labour + production overhead.
- Product costs attach to inventory under IAS 2: material, conversion and other costs to bring inventory to its present location and condition. Selling and administrative costs are period costs.
- Fixed, variable, semi-variable and stepped costs behave within a relevant range. Classification is purpose-specific: absorption costing treats fixed production overhead as a product cost; marginal costing does not.
Worked example
A factory produces 2,000 chairs. Direct material is ₦40,000; direct labour ₦25,000; direct expenses ₦5,000; factory rent ₦18,000; supervisor salary ₦12,000; sales commission ₦8,000. Prime cost is 40,000+25,000+5,000=₦70,000. Conversion cost is 25,000+18,000+12,000=₦55,000. Product cost under absorption is 70,000+18,000+12,000=₦100,000; sales commission is a period cost. The reasoning: rent and supervisor salary are production overhead, not prime cost, and commission is not incurred to bring inventory to a saleable condition.
Traps that cost marks
Treating all fixed costs as product costs; omitting direct expenses from prime cost; adding selling costs to inventory; assuming a cost is always fixed; ignoring the relevant range when projecting step costs.