Cost Structure

A cost structure is the architecture of how a business consumes resources --- the balance between fixed costs (which persist regardless of activity) and variable costs (which scale with output).

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What is it?

The revenue-and-expense concept showed that expenses are value consumed. A cost structure describes the shape of those expenses: which are fixed (unchanged by activity level), which are variable (proportional to output), and which are discretionary (optional).¹

This shape determines how a business behaves under stress and under growth. A business with high fixed costs and low variable costs (a software company, a training academy) has high operating leverage --- small changes in revenue produce large changes in profit, both up and down. A business with low fixed costs and high variable costs (a consulting firm, a marketplace) has low operating leverage --- profit moves proportionally with revenue.

In plain terms

Fixed costs are the cover charge. Variable costs are drinks at the bar. A venue with a high cover charge and cheap drinks benefits enormously from a packed house but bleeds when it is empty.

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How does it work?

The three types

Type	Behaviour	Examples
Fixed	Constant regardless of output	Rent, salaries, insurance, software subscriptions, depreciation
Variable	Scales with output	Materials, commissions, transaction fees, shipping
Discretionary	Optional, adjustable	Marketing, travel, training, R&D

Operating leverage

High fixed costs create operating leverage. If a software company has CHF 80K/month in fixed costs and CHF 5/user in variable costs, selling 1,000 users generates CHF 100K revenue and CHF 15K profit. Selling 2,000 users generates CHF 200K revenue and CHF 110K profit. Revenue doubled; profit multiplied by 7×.

But the reverse is equally true. Dropping from 1,000 to 500 users means CHF 50K revenue against CHF 82.5K costs --- a CHF 32.5K loss. High operating leverage amplifies both success and failure.

For your ventures

As a training provider building toward independence, your cost structure is strategically important:

• Training programmes have high variable costs (your time per session) --- each additional session costs almost as much to deliver as the first
• Digital content and platforms have high fixed costs (creation time, hosting) but near-zero variable costs per user --- operating leverage is high
• Workshops are mixed: venue and prep are semi-fixed, but each attendee adds minimal variable cost

The path from consulting (high variable) to platform (high fixed, low variable) is a cost structure migration that increases operating leverage and scalability.

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Check your understanding

Five questions (click to expand)

1. Classify the costs of a business you know into fixed, variable, and discretionary. Which category dominates?
2. Explain operating leverage. Why does high operating leverage make a business both more rewarding and more dangerous?
3. Compare the cost structure of a consulting firm vs a SaaS company. How does this shape their behaviour during a revenue decline?
4. Design the cost structure of a training business that transitions from in-person delivery to a digital platform. What shifts?
5. Connect cost structure to break-even. How does a high-fixed-cost business calculate its break-even point differently from a high-variable-cost one?

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Where this concept fits

Where this concept fits

graph TD
    RE[Revenue and Expense] --> CS[Cost Structure]
    A[Asset] --> CS
    DEP[Depreciation] --> CS
    CS --> MG[Margin]
    CS --> BE[Break-Even]
    style CS fill:#4a9ede,color:#fff

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Sources

Footnotes

1. Brealey, R. A., Myers, S. C., & Allen, F. (2020). Principles of Corporate Finance. Chapter 9 on operating leverage and cost behaviour. ↩