The paper examines depreciation as an effective tool for replenishing one’s investment resources. The theoretical foundations of depreciation and its significance in business management and financial management are discussed here based on the processes of simple and expanded capital reproduction of the company. The significant features of simple and expanded reproduction, which lie precisely in the possibility of capitalization of financial resources invested in production funds, are separately noted. The place and role of depreciation at various stages of social production reproduction are determined. Depreciation in this case serves as a tool for capitalizing resources. The circulation process of the main production capital (MPC) at various stages, namely, circulation, production, and circulation, is examined. The peculiarity of creating the final material product, which precisely allows for the capitalization of financial resources, is highlighted, and the secondary role of expenditure processes in circulation without which the realization of the finished product is not possible is determined. It is determined that the useful value of the main production capital (MPC) is the means of labor that have useful properties for production: they participate in the process of creating new useful value. MPC as value is social labor embodied. The activation of the reproduction of the main capital implies, first of all, the acceleration of its real circulation, which is manifested in the reduction of the reproduction cycle. And since the reproduction cycle of the main capital includes stages of innovative production, industrial production, testing, operation, and replacement, its reduction contributes to the renewal, modernization of means of labor, optimal use of available production capacities, which allows increasing capital productivity and production efficiency as a whole. All possible alternative sources of forming investment resources of enterprises are considered in the study, where separate instruments that can be applied to the reproduction process are distinguished. It is determined that leasing deserves separate attention as a tool of amortization reproduction, since it has certain features of depreciation accrual and its accounting on the company’s accounts depending on the methods of depreciation and the chosen type of leasing. The problem of effective reproduction of the company’s capital is considered from various points of view and at different levels of management.