We examine the associations between leverage, corporate and personal taxes, and the
firm’s implied cost of equity capital. Expanding on Modigliani and Miller [1958, 1963],
the cost of equity capital can be expressed as a function of leverage and corporate and
investor level taxes. This expression predicts that the cost of equity is increasing in
leverage, but that corporate taxes mitigate this leverage related risk premium, while the
personal tax disadvantage of debt increases the premium. We empirically test these
predictions using implied cost of equity estimates and proxies for the firm’s corporate tax
rate and the personal tax disadvantage of debt. Our results suggest that the equity risk
premium associated with leverage is decreasing in the corporate tax benefit from debt.
We find some evidence that the equity risk premium associated with leverage is
increasing in the personal tax penalty associated with debt