Marginal costing is a cost accounting method that assigns only variable costs to products while treating fixed costs as period expenses. By showing how costs and profits change with each additional unit produced, it helps businesses make informed decisions on pricing, production levels, product mix and short-term profitability.
Because it highlights the contribution earned from sales after covering variable costs, marginal costing is widely used for operational planning and decision-making.
What is marginal costing?
Marginal costing is a cost accounting technique that calculates product cost using only variable costs such as direct materials, direct labour and variable overheads. Fixed costs such as rent, salaries and depreciation are not included in product cost and are treated as period expenses.
It is used for internal planning and decision-making. However, it is not used for statutory inventory valuation because Indian Accounting Standard (Ind AS) 2 and Indian GAAP require fixed production overheads to be included in inventory costs.
What is the marginal costing formula?
The marginal cost equation ties together five variables. These are sales (S), variable cost (V), contribution (C), fixed cost (F) and profit (P).
S − V = C = F ± P
From this, these formulas follow:
(i) Contribution = S − V
What remains from sales revenue after variable costs are removed. This is what covers fixed costs and, beyond that, generates profit.
(ii) P/V ratio = (Contribution per unit / Selling price per unit) × 100 or (C / S) × 100
The profit volume ratio expresses contribution as a percentage of sales. A higher ratio means a larger share of each rupee of sales becomes contribution, so profits rise faster once the break-even point is crossed.
(iii) Break-even point (units) = (Fixed costs) / (Contribution per unit)
Break-even point (value) = (Fixed costs) / (P/V ratio)
The break-even point is the output level at which contribution and fixed costs are equal. There is no profit, no loss.
Example: A company makes a single product. Its variable cost is ₹300 per unit, and its fixed cost is ₹2,00,000 per month. The product is sold at ₹500 per unit.
Contribution per unit = ₹500 − ₹300 = ₹200
P/V ratio = (₹200 / ₹500) × 100 = 40%
Break-even point (units) = ₹2,00,000 / ₹200 = 1,000 units
Break-even point (value) = ₹2,00,000 / 40% = ₹5,00,000
On selling 1,000 units, all fixed costs are recovered. Every unit sold beyond that point earns a profit of ₹200.
What are the assumptions of marginal costing
The assumptions of marginal costing are:
- Variable cost per unit remains constant.
- The selling price per unit remains constant.
- Fixed costs remain unchanged within the relevant range of activity.
- Costs can be accurately classified into fixed and variable components.
- Production volume and sales volume are assumed to be equal for analytical purposes unless stated otherwise.
What are the key features of marginal costing
Marginal costing is characterised by the separate treatment of variable and fixed costs for decision-making and profit analysis.
- Separation of costs: Costs are classified as fixed or variable at the outset. The entire analysis depends on this sorting being done correctly.
- Contribution over gross profit: Performance is measured by contribution, which shows how much each product or segment contributes to fixed costs and profit.
- Fixed costs treated as period costs: Rather than attaching fixed costs to units, the full amount is charged to the profit and loss account in the period in which they are incurred.
- Stock valued at variable cost: Closing inventory is valued at variable cost only, so profit does not shift based on the amount of stock at period end.
How is marginal costing different from absorption costing
Marginal costing differs from absorption costing in the treatment of fixed costs, inventory valuation, profit measurement and reporting purpose.
|
Basis |
Marginal costing |
Absorption costing |
|
Fixed cost treatment |
Period cost, kept out of product cost |
Absorbed into each unit of output |
|
Stock valuation |
Variable cost only |
Full production cost including fixed overheads |
|
Profit reporting |
Contribution based |
Gross profit based |
|
Statutory use |
Internal management use only |
Mandatory under Ind AS 2 and Indian GAAP |
|
Best suited for |
Short-term operational decisions |
Long-term pricing and published accounts |
What are the applications of marginal costing
Marginal costing is used for special-order evaluation, product-mix decisions, make-or-buy analysis and short-term pricing decisions.
- Special orders: When a buyer offers a price below the standard rate, the relevant question is whether it covers variable cost and leaves a positive contribution. Since fixed costs are already committed, any additional contribution improves overall results.
- Product mix under capacity constraints: A factory constrained by machine hours or labour availability uses contribution per unit of the scarce resource to decide which products should receive the available capacity.
- Make-or-buy decisions: Comparing in-house variable costs with a supplier's quoted price helps determine whether outsourcing is financially viable. Fixed costs are excluded because they will be incurred regardless of the decision.
- Pricing for new markets or short-run contracts: For export orders or seasonal work, the minimum acceptable price is the variable cost per unit. Any amount above it contributes towards fixed cost recovery and profit.
Limitations of marginal costing
Despite its practical value, marginal costing has a few clear limitations.
- Incomplete cost picture: Fixed costs are left out of product cost entirely, which means the figures do not reflect the full cost of running the business.
- Long-run underpricing: Pricing just above variable cost may work for a one-off order, but using it repeatedly can leave fixed costs unrecovered and reduce profitability.
- Not valid for statutory reporting: Ind AS 2 requires inventory to be valued at full production cost. As a result, absorption costing is still required for financial reporting and compliance.
- Unreliable in capital-intensive settings: Where fixed costs account for a large share of total expenditure, excluding them from product cost can distort product-level profitability analysis.
Conclusion
Marginal costing is a valuable decision-making tool because it highlights how changes in sales volume, costs and pricing affect profitability. While it provides clear insights for short-term planning, it should be used alongside other costing methods to understand the full cost of operations and support long-term decisions.
By accurately tracking and classifying fixed and variable costs, TallyPrime helps businesses generate the reliable data needed for effective marginal costing analysis and better-informed financial decisions.
