The cost of capital and leverage are not always constant, even if the debt level stays the same. The discount rate used to value tax shields affects the cost of equity and the Weighted Average Cost of Capital (WACC). For finite cash flows, these values can change over time, depending on how tax shields are discounted. Different methods of valuation can lead to varying results, showing that assumptions of constant leverage may not always hold true. This means that the cost of equity and WACC can fluctuate with changes in the discount rate for tax shields, especially for finite cash flows.