Management Accounting · Accounting for material, labour and overheads

Marginal vs Absorption Costing Profit Reconciliation Explained

Q: Why does absorption costing profit change when inventory changes?

Absorption costing includes fixed production overhead in the value of inventory. When inventory rises, part of the period's fixed overhead is carried forward instead of charged to profit. When inventory falls, overhead from earlier periods is released into the current period's cost of sales.

Q: Which method gives a higher profit?

It depends on the inventory movement. If closing inventory is higher than opening inventory, absorption costing gives the higher profit. If it is lower, marginal costing gives the higher profit. If it is unchanged, the profits are equal.

Q: Do I need to reconcile over- or under-absorbed overhead as well?

Not in the basic reconciliation. The standard adjustment is based on the change in inventory and the fixed overhead rate per unit. Over- or under-absorption is a separate adjustment to absorption costing profit and is handled separately.

Q: What costs are in inventory under marginal costing?

Only variable production costs: direct materials, direct labour and variable production overhead. Fixed production overhead is charged in full to the period. Non-production costs are never included in inventory.

Updated 11 October 2026 · Fact-checked

Absorption costing includes fixed production overheads in inventory value. Marginal costing treats them as a period cost. When inventory changes, profits differ by the change in inventory units × the fixed overhead absorbed per unit. Inventory up means absorption profit is higher. Inventory down means it is lower.

Understand Marginal vs Absorption Costing Profit Reconciliation

Both methods value sales the same way and treat variable costs the same way. The only difference is fixed production overhead. Marginal costing values inventory at variable production cost only and writes off all fixed production overhead in the period it is incurred. Absorption costing values inventory at full production cost, which includes a share of fixed production overhead.

This matters when units produced differ from units sold. Under absorption costing, some fixed overhead sits inside closing inventory. That cost is carried forward in the statement of financial position and is not charged to profit this period. Under marginal costing, the full fixed overhead is charged now.

So the profit gap comes from fixed overhead moving in or out of inventory. If you produce more than you sell, inventory rises. Absorption costing defers some fixed overhead, so its profit is higher. If you sell more than you produce, inventory falls. Absorption costing releases fixed overhead held in opening inventory, so its profit is lower.

If inventory does not change, the two profits are equal. Production equals sales, and the same fixed overhead is charged under both methods.

A reconciliation simply starts with one profit and adjusts for this difference to reach the other. In the exam, you may also be asked which profit is higher, or to calculate the difference only. Remember that only fixed production overhead is affected. Selling and administration costs are period costs under both methods.

Key formulas to remember

Profit difference: Absorption profit − Marginal profit = (Closing inventory units − Opening inventory units) × Fixed overhead absorption rate per unit; Use the rate per unit actually used in absorption costing. A negative result means absorption profit is lower.
Fixed overhead absorbed per unit: Budgeted fixed production overhead ÷ Budgeted activity level; Activity is usually units or labour/machine hours. If hours are used, convert to a rate per unit.
Marginal costing inventory value: Variable production cost per unit × units in inventory; Includes direct materials, direct labour and variable production overhead only.
Absorption costing inventory value: (Variable production cost + Fixed overhead per unit) × units in inventory; Valued at full production cost.
Reconciliation rule: Inventory increases: absorption profit > marginal profit. Inventory decreases: absorption profit < marginal profit. No change: profits equal.; Assumes the same fixed overhead absorption rate is used in both periods.

How to solve Marginal vs Absorption Costing Profit Reconciliation questions

Use this method for any question that asks you to compare or reconcile the two profits.

1Write down opening inventory, production and sales in units. Calculate closing inventory = opening + production − sales.
2Find the change in inventory: closing minus opening. Note if it is an increase or a decrease.
3Calculate the fixed production overhead absorbed per unit (budgeted overhead ÷ budgeted activity).
4Multiply the change in inventory units by the fixed overhead per unit. This is the profit difference.
5Decide the direction: inventory up means absorption profit is higher; inventory down means it is lower.
6Start with the profit you are given. Add or subtract the difference to reach the other profit.
7Check: (absorption closing inventory − marginal closing inventory) − (absorption opening inventory − marginal opening inventory) = absorption profit − marginal profit.

Quickest way: Change in inventory × fixed overhead per unit

When to use it: Use this for number-entry or multiple-choice questions that give units and a fixed overhead rate and ask for a profit difference or the other profit.

Work out closing inventory units and the change in inventory.
Multiply the change by the fixed overhead per unit.
Up means absorption profit is higher, so marginal profit = absorption profit − adjustment.
Down means absorption profit is lower, so marginal profit = absorption profit + adjustment.
Sense check: no inventory change means the profits are equal.

Common mistakes in Marginal vs Absorption Costing Profit Reconciliation

Using total fixed overhead instead of fixed overhead per unit in the adjustment.
Students remember that fixed overhead causes the difference and use the whole amount.
Fix: Only the fixed overhead sitting in the inventory change matters. Multiply the change in units by the rate per unit.
Adding the adjustment in the wrong direction.
Students memorise a direction without thinking about why.
Fix: Ask whether fixed overhead is being deferred into inventory (absorption profit higher) or released from inventory (absorption profit lower).
Including variable costs or selling costs in the adjustment.
Students confuse 'full cost' with all costs.
Fix: Only fixed production overhead is affected. Variable costs and non-production overheads are treated the same under both methods.
Using production units instead of the change in inventory units.
The question gives production and sales figures, and students grab the wrong one.
Fix: Always calculate closing inventory first. The adjustment depends on inventory change, not on production alone.
Ignoring opening inventory when it is not zero.
Many practice questions start with nil inventory, so students forget opening inventory exists.
Fix: Use closing minus opening units. If both are positive, the net change is what counts.
Using the actual overhead per unit instead of the absorption rate.
Questions may include both actual and budgeted overhead figures.
Fix: Use the predetermined absorption rate. Any over- or under-absorption is a separate adjustment.

Worked examples

Example 1

A company produced 10,000 units and sold 8,000 units in a month. There was no opening inventory. Budgeted fixed production overhead is $50,000 for budgeted production of 10,000 units. Marginal costing profit is $62,000. Calculate the absorption costing profit.

Show the solution

Closing inventory = 0 + 10,000 − 8,000 = 2,000 units.
Change in inventory = 2,000 − 0 = an increase of 2,000 units.
Fixed overhead per unit = $50,000 ÷ 10,000 = $5.
Adjustment = 2,000 × $5 = $10,000.
Inventory has increased, so absorption profit is higher: $62,000 + $10,000 = $72,000.

Answer: Absorption costing profit = $72,000.

Example 2

In the next month, the company has opening inventory of 2,000 units, produces 9,000 units and sells 10,000 units. The fixed overhead absorption rate is still $5 per unit. Absorption costing profit is $95,000. Calculate the marginal costing profit.

Show the solution

Closing inventory = 2,000 + 9,000 − 10,000 = 1,000 units.
Change in inventory = 1,000 − 2,000 = a decrease of 1,000 units.
Adjustment = 1,000 × $5 = $5,000.
Inventory has decreased, so absorption profit is lower than marginal profit.
Marginal profit = $95,000 + $5,000 = $100,000.
Check: opening inventory under absorption costing includes $10,000 of fixed overhead (2,000 × $5) and closing inventory includes $5,000 (1,000 × $5). The net release into this period is $10,000 − $5,000 = $5,000, so absorption profit is $5,000 lower.

Answer: Marginal costing profit = $100,000.

Exam tips

Calculate closing inventory units first in every question. It tells you the direction of the profit difference immediately.
In multiple-choice questions, eliminate options by direction. If inventory rises, any option with absorption profit below marginal profit is wrong.
Check which overhead is fixed production overhead. Remove selling, distribution and administration costs from the adjustment.
In number-entry questions, enter the figure only in the format the question asks for, and check whether it wants a profit or a difference.
If the question uses hours for absorption, convert the rate to fixed overhead per unit before multiplying by the change in units.

Practice questions from Accounting for material, labour and overheads

Marginal vs Absorption Costing Profit Reconciliation in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Marginal vs Absorption Costing Profit Reconciliation: frequently asked questions

Why does absorption costing profit change when inventory changes?

Absorption costing includes fixed production overhead in the value of inventory. When inventory rises, part of the period's fixed overhead is carried forward instead of charged to profit. When inventory falls, overhead from earlier periods is released into the current period's cost of sales.

Which method gives a higher profit?

It depends on the inventory movement. If closing inventory is higher than opening inventory, absorption costing gives the higher profit. If it is lower, marginal costing gives the higher profit. If it is unchanged, the profits are equal.

Do I need to reconcile over- or under-absorbed overhead as well?

Not in the basic reconciliation. The standard adjustment is based on the change in inventory and the fixed overhead rate per unit. Over- or under-absorption is a separate adjustment to absorption costing profit and is handled separately.

What costs are in inventory under marginal costing?

Only variable production costs: direct materials, direct labour and variable production overhead. Fixed production overhead is charged in full to the period. Non-production costs are never included in inventory.