This report provides an in-depth analysis of optimal leverage within the context of corporate finance, focusing on the implications of various capital structure theories. It begins by defining leverage and optimal leverage, emphasizing the role of debt-to-equity ratios in a company's capital structure. The report then explores several capital structure theories, including the trade-off theory, the Modigliani and Miller theory, the agency theory, and the traditional theory approach, highlighting their varying impacts on financing decisions. The agency theory, for instance, is discussed in terms of its implications for balancing shareholder dividends and stakeholder requirements. The trade-off theory is examined, focusing on the balance between debt and equity, tax benefits, and financial distress costs. The report also delves into the analysis of tax benefits, particularly franking credits in the Australian context, and the implications of the trade-off theory. The report examines the relationships between profitability, uncertainty of operating income, growth opportunities, and the types of assets a company holds, and their influence on leverage decisions. The report concludes by referencing relevant literature to support its analysis.