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Microlesson · 5-min read

Meaning and Optimum Capital Structure

## Capital Structure – Meaning & Optimum Mix

### What Is Capital Structure?

Capital structure is the combination of capitals from different sources used to finance a company's assets.

It typically includes:

  • Equity shareholders' fund
  • Preference share capital
  • Long-term external debts (loans, debentures)

### Three Design Principles

PrincipleWhat It Means
ControlExisting shareholders should retain majority stake
RiskFinancial risk should not exceed a tolerable limit
CostOverall cost of capital should remain minimum

### Why Is Debt Called 'Cheaper'?

Three reasons debt is preferred over equity as a source of finance:

1. Tax Benefit – Interest is tax-deductible, reducing taxable income (unlike dividends).

2. No Dilution of Control – Borrowing does not affect ownership; new equity dilutes existing shareholders.

3. Lower Required Return – Creditors accept lower returns because they have priority over shareholders in repayment (lower risk).

### Optimum Capital Structure

The optimum capital structure is the specific mix of debt and equity where:

  • The firm's overall cost of capital is minimised, AND
  • The value of the firm is maximised.

It balances two opposing forces:

DebtEquity
Provides tax benefits (interest deduction)Safer and more flexible
Increases financial riskMore expensive (shareholders expect higher returns)

> Key Insight: The optimum point is where advantages of debt are fully utilised without letting the risk of insolvency outweigh them.

Worked example

### Example 1

Example – Tax Shield on Debt:

A firm borrows ₹10,00,000 at 10% interest. Interest = ₹1,00,000. If tax rate is 30%, the actual after-tax cost = ₹1,00,000 × (1 – 0.30) = ₹70,000. This tax saving is the 'tax shield' that makes debt cheaper than equity.

### Example 2

Example – Control Dilution:

A promoter holds 60% of 10,00,000 shares. If the company issues 5,00,000 new shares for expansion, promoter's stake falls to 60%/150% = 40% — losing majority control. Using debt instead avoids this.

⚠️ Common exam mistakes

  • Confusing 'capital structure' with 'financial structure' — capital structure covers only long-term funds; financial structure includes all liabilities including current.
  • Assuming lower cost of debt always means maximum debt is best — ignoring the financial risk increase as debt rises.
  • Forgetting that the control principle and cost principle can conflict: debt preserves control but increases risk.
Reference:
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