ACCT2019 Chap.3 Absorption and Variable Costing
Absorption and Variable Costing
Absorption and variable costing differ in when fixed manufacturing overhead reaches operating income. Absorption costing attaches it to inventory; variable costing expenses it in the period. When inventory rises, absorption costing defers overhead and reports higher income. When inventory falls, it releases overhead and reports lower income.
The chapter uses that direction rule, an overhead rate and inventory movement to reconcile profit and diagnose incentives to overproduce. Both methods recognise the same total fixed manufacturing resource cost over time, but the timing changes while units remain in inventory. Selling and administrative costs stay outside this manufacturing bridge.
A reconciliation is strongest when it predicts the sign from inventory movement, calculates the rate multiplied by the change in units, and then explains where the overhead sits. Management analysis goes further by asking whether production matches demand, because unsold output can lift current absorption income while increasing storage, obsolescence and later reversal risk.
Comparing multiple periods reveals the reversal: overhead deferred in one period reaches expense when those units are sold later. That is why an isolated income improvement should be read beside inventory volume and sales demand. Pairing profit with inventory quantity and demand evidence makes the timing effect visible and reduces the temptation to treat stored overhead as economic improvement.
What this chapter covers
- 01
Variable manufacturing product cost
- 02
Absorption product cost
- 03
Fixed overhead timing
- 04
Inventory movement and income
- 05
Profit reconciliation
- 06
Overproduction incentives
Worked example · free
Reconciling income after inventory falls
- +1AskSia-authored drill allocation. Fixed manufacturing overhead rate is $177,000 / 5,900 = $30 per unit.
- +1Inventory falls by 6,200 - 5,900 = 300 units.
- +1Absorption costing releases $30 x 300 = $9,000 of fixed overhead from inventory.
- +1Absorption income is $146,000 - $9,000 = $137,000.
- +1The lower absorption result matches the direction predicted by falling inventory.
Key terms
- Variable Costing
- An inventory method that includes variable manufacturing cost and expenses fixed manufacturing overhead immediately.
- Absorption Costing
- An inventory method that includes variable and fixed manufacturing cost in product cost.
- Overhead Rate
- Fixed manufacturing overhead assigned to each unit using the chosen denominator level.
- Inventory Change
- Production less sales, indicating whether units and attached absorption cost are stored or released.
- Overproduction Incentive
- Pressure to produce beyond demand because overhead deferral can increase current absorption income.
Absorption and Variable Costing FAQ
Why do the two methods report different profit?
They recognise fixed manufacturing overhead at different times. Variable costing expenses the period total immediately. Absorption costing holds part in inventory until the related units are sold, so changing inventory produces a temporary income difference.
What happens when production equals sales?
With no relevant opening difference, inventory does not change and the same fixed manufacturing overhead reaches income under both methods. The reconciliation is zero because the overhead rate multiplied by the inventory change is zero.
Why can absorption costing affect behaviour?
Producing units that are not sold can defer fixed manufacturing overhead in inventory and increase current reported income. Managers should monitor inventory, demand, capacity and later write-down risk so production is not rewarded independently of sales.
Exam move
Draw two boxes labelled product cost and period cost, then place variable manufacturing, fixed manufacturing and selling costs under each method. After that, practise only the reconciliation until the sign is automatic. Use three cases: inventory rises, falls and remains unchanged. For every result, write a sentence about overhead being deferred or released rather than saying simply that one method is higher.
Rebuild a short income statement occasionally to confirm the bridge, but use the rate-times-inventory-change shortcut for checking. Add a behavioural paragraph explaining why production without demand can improve absorption income today while increasing storage, obsolescence and future expense. That final link turns a mechanical reconciliation into management accounting analysis.
Create a four-period schedule in which inventory first rises, then remains steady, then falls. Track the fixed overhead held in opening and closing inventory and confirm that temporary income differences reverse as units are sold. Change the denominator level while keeping total fixed overhead constant so you can see how the unit rate changes.
Explain why that allocation effect does not change the factory's total resource cost. Next, list three controls that discourage overproduction: inventory targets, non-financial demand measures and performance evaluation based on both profit and working capital. Practise spotting selling and administrative cost in a question and keep it out of the manufacturing-cost bridge unless the facts create a separate decision effect.
Your final revision check is verbal: if production exceeds sales, say which method is higher and why before using any numbers.
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