A cake shop buys eggs, flour, butter, rents a kitchen, pays a baker. What does one cake cost to make? "Total expense divided by number of cakes" is first-year thinking. Costing is what separates a baker from a business owner: direct vs indirect, fixed vs variable, historic vs standard, absorption vs marginal. Each decomposition answers a different question, and the CMA / CA exam tests all four across numerical and conceptual questions. Master the four and you solve 70%+ of a costing paper on structure alone.
By the end, you will know the four costing classification frameworks CMA Foundation tests you on, the decision each enables, and the exam pattern that rewards systematic decomposition over formula memorisation.
The four decompositions
- DIRECT vs INDIRECT: does the cost attach to ONE unit (direct) or spread across all (indirect)? Baker's wage on this-cake = direct. Rent = indirect (overhead). Direct materials + direct labour + direct expenses = prime cost.
- FIXED vs VARIABLE: does total cost change with volume (variable. Flour, eggs, packaging) or stay flat (fixed. Rent, insurance, salaries) in the short run? Semi-variable costs (electricity with fixed + consumption components) exist as a hybrid.
- HISTORIC vs STANDARD: actual past cost (historic) or planned / target cost (standard)? Variance analysis = difference between the two, broken into price variance, quantity variance, efficiency variance.
- ABSORPTION vs MARGINAL: does overhead get absorbed into unit cost (absorption. Full cost) or treated as period cost (marginal. Variable-only cost)? Different inventory valuations result.
The four are not interchangeable. Each is a different axis. A single cost can be direct + variable + historic + absorbed into unit cost. The classifications serve different decisions; exam questions test whether you can apply the right one to the right problem.
What decision each answers
- Direct / indirect to unit-costing for pricing (what cost must I charge per cake to break even + margin?).
- Fixed / variable to break-even analysis, contribution margin analysis, operating leverage.
- Historic / standard to variance analysis + performance management (are operations running as planned?).
- Absorption / marginal to make-or-buy decisions, accept-or-reject one-time orders, transfer pricing.
The most-tested pairing: marginal costing for short-run decisions. A one-time order at discounted price. Is it worth accepting? Marginal (variable-only) cost sets the floor; fixed costs are "sunk" for the period. Absorption costing would reject profitable marginal orders by loading fixed costs onto each unit. This distinction is worth 15-20% of any CMA Foundation costing paper.
Typical exam problem: schedule of costs (materials, labour, overhead, selling, admin) to asked to compute (a) total direct cost, (b) absorption rate per unit, (c) profit under absorption vs marginal costing. The "trick" is almost always in classifying semi-variable costs correctly: electricity fixed + variable, supervisory salary fixed, factory maintenance partly semi-variable. Misclassify and every downstream number breaks.
Second common pattern: break-even analysis. Fixed costs + target profit divided by contribution margin per unit = target units. Contribution margin = selling price - variable cost per unit. Operating leverage = contribution margin / profit. These three formulas compose together; learn them as a set.
