When considering the impact of corporate taxes on capital structure decisions, Franco Modigliani and Merton Miller (MM) extended their propositions to incorporate the effect of taxes. These are known as the Modigliani-Miller propositions with corporate taxes. Let’s discuss the key aspects of MM’s propositions with corporate taxes:
- MM Proposition I (With Corporate Taxes): MM Proposition I with corporate taxes states that the value of a firm is still independent of its capital structure, but taxes can create a benefit from debt financing. Specifically, the proposition argues that the total market value of a firm is determined by its cash flows and risk, but the presence of corporate taxes makes debt financing advantageous. This is because interest payments on debt are tax-deductible expenses, reducing the firm’s taxable income and thus its tax liability. As a result, the tax shield benefit from debt can increase the overall value of the firm.
- MM Proposition II (With Corporate Taxes): MM Proposition II with corporate taxes suggests that the cost of equity is still directly proportional to the firm’s leverage, but the cost of debt is reduced due to the tax advantage. The proposition states that as the firm increases its leverage, the cost of equity increases due to higher financial risk, but the tax benefits from debt lower the after-tax cost of debt. Therefore, the weighted average cost of capital (WACC) decreases as the proportion of debt in the capital structure increases.