Absorption Costing

Absorption costing, also called full costing, is a method of calculating the cost of a product or service that includes every cost of producing it: direct materials, direct labor, variable overhead and a share of fixed overhead. Each unit "absorbs" a portion of the fixed costs of production, such as factory rent, equipment depreciation and supervisors' salaries, in addition to its variable costs.

Absorption costing is required for external financial reporting under US GAAP and IFRS, where it determines the value of inventory and the cost of goods sold. Its counterpart, variable costing, is often used internally for decisions. For IT financial management, the same idea appears in full service costing, where technology services carry a share of all the costs that support them, and in debates about whether internal charges should recover fixed costs or only variable ones.

Definition of Absorption Costing

Absorption costing is a product costing method that includes all manufacturing or production costs, both variable and fixed, in the cost of each unit. Fixed overhead is allocated to units using a predetermined rate, usually based on expected production volume.

Non-production costs, such as selling and general administrative expenses, are not included in product costs under absorption costing. They are expensed in the period they are incurred.

Absorption vs Variable Costing

Variable costing, also called direct or marginal costing, includes only variable production costs in the cost of each unit. Fixed production overhead is treated as a period cost and expensed in full each period, regardless of how many units are produced or sold.

The two methods give different profit figures when production and sales differ. Under absorption costing, producing more than is sold defers some fixed overhead into inventory, raising profit in the current period. Under variable costing, profit depends only on sales. This difference is why variable costing is often preferred for internal decisions, since it cannot be used to raise reported profit simply by producing more.

Fixed Overhead Rates

Under absorption costing, fixed overhead is assigned using a rate calculated by dividing budgeted fixed overhead by budgeted activity, such as units or machine hours. If actual activity differs from budget, fixed overhead is under-absorbed or over-absorbed, and the difference is adjusted at period-end.

The choice of denominator matters. Using expected volume spreads fixed costs over planned output, while using practical capacity shows the cost of unused capacity separately, which can be more useful for management.

Importance of Absorption Costing in IT Financial Management

While absorption costing is formally a product costing rule for inventory, its principle, that every output should carry a fair share of the fixed costs that make it possible, is central to how technology services are costed and charged.

The tension between absorption and variable costing also appears in many IT pricing and sourcing decisions.

Full Cost of Technology Services

When IT calculates the cost of a service, such as hosting, storage or the service desk, it usually includes direct costs, variable costs and a share of fixed costs for shared infrastructure, management and overhead. This is an absorption approach, and it gives the full cost that an external provider would need to recover.

Full costs are the right basis for long-term pricing, benchmarking and IT chargeback rates intended to recover the full cost of IT. They show what a service costs to sustain over time.

Risks of Absorbed Costs in Decisions

Full absorbed costs can mislead short-term decisions. If a business unit reduces its use of a service, its chargeback falls by the full rate, but IT's fixed costs do not fall, so the remaining users absorb more. If too many units leave, the cost per unit rises in a spiral.

For short-term decisions, such as whether to accept an additional workload or move one to the cloud, the relevant costs are usually the variable and avoidable costs, not the full absorbed cost. Separating fixed vs variable costs in service costing makes this distinction visible.