Cost Classification and Cost Behaviour (Chapter 2)

SAPPI and cost classification

• Extract from SAPPI's 2018 integrated report (group statement of comprehensive income):
  • Sales revenue: $5{,}806$ (US$ million, 2018) vs $5{,}296$ (2017); change: $10\%$
  • Variable manufacturing and delivery costs: $3{,}521$ vs $3{,}147$; change: $12\%$
  • Fixed costs: $1{,}767$ vs $1{,}601$; change: $10\%$
  • Sundry items: $38$ vs $22$; change: $73\%$
  • Operating profit excluding special items: $480$ vs $526$; change: $-9\%$
• Observation: Most of the group\'s operating expenses are split into two categories: \'variable\' or \'fixed\'. This is a less common presentation format in a statement of comprehensive income.
• Central question: Why classify costs as fixed or variable, and why does SAPPI regard this distinction as important for understanding financial results?
• Answer (context): Understanding how management uses cost information for decision-making and control. Although SAPPI presents costs as fixed/variable in this format, cost analysis and management accounting rely on more than this single presentation approach.
• Chapter purpose: Examine how costs behave and how they are classified for management decision-making and control.

2.1 Introduction

• Key terms (introduced in this chapter):
  • assignment
  • cost behaviour
  • function
  • relevance
  • timing
• Why multiple classifications? Financial accounting classifications (revenue/expense, asset/liability/equity) are not sufficient for management purposes.
• Management objective: maximise shareholder value by increasing the organisation\'s value and future cash flows.
• How management uses financial information:
  • To decide on product/service ranges, extend/withdraw departments or divisions, accept/decline contracts and projects, etc.
  • To control actions of employees through financial mechanisms (e.g., performance evaluation and incentives).
• Managers view financial information from multiple perspectives to understand how actions affect the firm\'s value.
• The perspectives are based on the following attributes of cost information:
  • Cost behaviour
  • Assignment
  • Relevance
  • Function
  • Timing

2.1.1 Cost classification

• Cost information is viewed from five characteristics:
  • Cost behaviour: how a cost reacts to changes in sales volume, production volume, or other activity levels (e.g., number of machine set-ups). Four basic cost types introduced: variable, fixed, step, and mixed costs.
  • Assignment: tracing costs to cost objects (products, services, projects, customers, departments, divisions). Distinguishes direct vs indirect costs. Indirect costs (overheads) require allocation (Chapter 6 discusses this in depth).
  • Relevance: identify which costs and revenues are affected by a decision. Incremental (relevant) costs are those that will be changed by the decision. Irrelevant costs/revenues should be ignored in decision-making. (Further development in Chapter 10: Relevant costs for decision-making.)
  • Function: presentation of cost information by the function the cost serves (e.g., product-related costs vs support costs).
  • Timing: when a cost is recognised in the income statement (recognition period).
• Cross-cutting point: While these classifications are framed for private sector profit-seeking organisations, they are also relevant in public sector and not-for-profit contexts where resources are constrained and efficiency matters.

2.2 Cost behaviour

• Definition: Cost behaviour refers to how costs are affected by changes in activity levels (e.g., sales volume, production volume, or other activity such as machine setups).
• Purpose: to establish how changing production and sales levels will affect profitability.
• Four broad categories based on activity relationship:
  • Variable costs
  • Fixed costs
  • Step costs
  • Mixed costs

2.2.1 Variable costs

• Definition: Variable costs increase (or decrease) in proportion with changes in the level of activity.
  • If related to production activities (e.g., materials), total cost changes with production volume.
  • If related to sales (e.g., sales commissions), total cost changes with sales volume.
• Practical note: Some costs may change in relation to activity levels in a non-proportional or non-linear manner in practice, but the standard definition assumes a proportional relationship within the relevant range.
• Examples (illustrative, from context): materials costs tied to production; sales commissions tied to sales volume.
• Consequence for cost behaviour analysis: total variable cost varies with the level of activity, while the per-unit variable cost remains constant (within the relevant range).

Formulas (conceptual summaries)

• Variable cost behavior (production-related): $TC = v \, \cdot \, Q$ where:
  • $TC$ = total variable cost
  • $v$ = variable cost per unit
  • $Q$ = quantity of output
• Fixed cost behavior: $TC = F$ where:
  • $F$ = total fixed cost (does not change with activity level within the relevant range)
• Mixed cost behavior (semivariable): $TC = F + v \cdot Q$ where:
  • $F$ = fixed component
  • $v$ = variable component per unit
  • $Q$ = activity level
• Step costs: fixed within a band, then jump to a higher level when activity exceeds a threshold (conceptual representation; piecewise behavior than a single equation).

2.2.1 (continued) Notes on cost behaviour

• Distinctions among cost types are foundational for decision-making, budgeting, and performance evaluation.
• Cost behaviour knowledge supports the modelling of scenarios (e.g., what happens to profit if volume increases by X% or if a product line is dropped).

2.3 Assignment (preview context)

• Not fully detailed in this transcript excerpt, but key idea:
  • Direct costs can be traced to a specific cost object (product/service/department).
  • Indirect costs (overheads) require allocation to cost objects; Chapter 6 covers overhead allocation in depth.

2.4 Relevance for decision-making (preview context)

• Relevance focuses on incremental costs and revenues that will change as a result of a decision.
• Irrelevant costs (e.g., sunk costs) should not drive the decision.
• Further discussion appears in Chapter 10 (Relevant costs for decision-making).

2.5 Function and timing (preview context)

• Function: categorize costs by the purpose or activity the cost supports within the organisation (e.g., production vs administration).
• Timing: determine when a cost is recognized in financial statements (period in which the cost is incurred or matched).

2.6 Relevance across organisations

• Cost classification and behaviour are important not only in private sector profit-maximising contexts but also in public-sector and not-for-profit settings where resources are constrained.
• Understanding costs supports efficient operation and better resource allocation.