In this paper, we describe new investment models with uniform debt repayment during the life of the project, quite adequately describing real investment projects. Within these models, it is possible, in particular, to analyze the dependence of effectiveness of investment projects on debt financing and taxation. We will work within the modern Brusov–Filatova–Orekhova theory of capital cost and capital structure as well as within a perpetuity limit. © 2016, Springer Science+Business Media New York.