One of the main parameters of business valuation and company value is the company’s income flow. Determining the appropriate income flows of a company is a complex and time-consuming task. Dividends paid to shareholders of a company represent a significant amount of income, but determining the adequate size of dividends is a complex problem. The economically justified amount of dividends is equal to the equity cost, assuming that investors use a dividend discounting model. The evaluation of the latter is an extremely difficult task. It is possible to do this within modern capital structure theory—Brusov–Filatova–Orekhova (BFO)—or within its perpetual limit—the Мodigliani–Мiller (MM) theory. After the recent generalization of both theories, taking into account the real conditions of the functioning of the companies, it becomes possible to estimate the cost of equity in these conditions. Dependence of the cost of equity on the level of leverage for different age of the company, different values of k0 (cost of equity at zero leverage level L) and debt costs, for different frequencies of income tax payment, for advance payments of income tax and payments at the end of periods, for variable income of companies, etc. is being studied. Several very important innovative effects have been discovered, which significantly change the company’s dividend policy. The developed methodology and results will help the company’s management to develop an adequate and effective dividend policy. This chapter examines in detail the problem of forming a company’s dividend policy, determining the value of dividends, and the impact on their size and on the size of the company’s income, used in assessing the business and the company, the real conditions of the companies’ functioning.