Cost Classification Edge Cases
Questions that seem contradictory until you apply the frameworks carefully.
Q: Why is factory supervisor salary a product cost but not administrative?
Answer: Location determines product vs. period.
| Role | Location | Classification |
|---|---|---|
| Factory supervisor | Manufacturing floor | Product cost (MOH) |
| HR manager | Corporate office | Period cost (admin) |
Administrative = general management of the organization Product = incurred in the factory
Q: Why is electricity per machine-hour variable, but machine rental fixed?
Answer: Cost structure, not the item itself.
| Cost Structure | Behavior |
|---|---|
| $2 per machine-hour consumed | Variable (more production = more cost) |
| $8,000/month rental regardless of use | Fixed (same cost at any volume) |
The machine rental is like the hospital diagnostic machine—capacity exists whether you use it or not.
Q: Why is sales commission “variable + selling” not “mixed”?
Answer: Mixed requires a fixed component.
| Structure | Classification |
|---|---|
| $30 per table sold (only) | Pure variable |
| Base salary + commission | Mixed |
If zero tables sold → zero commission cost → pure variable.
Q: Why is overtime indirect when regular assembly labour is direct?
Answer: Traceability, not the worker.
| Cost | Traceable to specific tables? | Classification |
|---|---|---|
| $40 assembly wage per table | Yes—you know which tables | Direct |
| $10,000 overtime across all product lines | No—can’t attribute to specific units | Indirect |
The overtime was incurred “when demand was high across all product lines”—you’d have to allocate, not trace.
Practical Note
You could trace overtime with detailed time tracking. The “indirect” classification is a practical choice, not physical impossibility. Modern systems may justify more granular tracking.
Q: Can the same cost be both direct and indirect?
Answer: Yes, depending on cost object.
| Cost | Direct to… | Indirect to… |
|---|---|---|
| Factory manager salary | Manufacturing division | Individual product |
| Battery | Specific vehicle | The factory |
Always ask: “Direct to what?”
Classification Decision Tree
- Where incurred? Factory → product cost path. Elsewhere → period cost.
- Traceable to cost object? Yes → direct. No → indirect.
- Behaviour with volume? Changes proportionally → variable. Constant total → fixed.
Apply all three independently.
North: Where this comes from
- Cost Classification Framework (the three-axis system)
- Cost Object (why the same cost can classify differently)
East: What opposes this?
- Oversimplified Classification (treating costs as having one “true” category)
South: Where this leads
- Exam Problem Solving (apply decision tree systematically)
- Real-World Judgment (when conventions don’t fit)
West: What’s similar?
- Context-Dependent Classification (same item, different category based on use)