§ 21. Capital structure. The capital structure of a company undertaking a project and the proportionate amount of the project cost to be represented by mortgages, bonds, notes, income debentures and shares shall be subject to the approval of the commissioner except as otherwise provided in section twenty-three with respect to a municipally-aided project. The shares and income debentures issued by a mutual company or urban rental company, other than a non-profit company incorporated pursuant to the provisions of the not-for-profit corporation law and this article for the purpose of providing housing for staff members, employees or students of a college, university, hospital or child care institution and their immediate families or for aged or handicapped persons of low income, and other than a municipally-aided non-profit company or a municipally-aided mutual company, and other than a low income non-profit housing company, shall not be less than the total of five per centum of the project cost. The shares, bonds or notes, income debentures and mortgages covering any project shall not exceed the actual project cost.

The provisions of this section with respect to the proportionate amount of the project cost to be represented by mortgages, bonds, notes, income debentures and shares shall not be applicable to any housing company project, if funds made available by the federal government or any agency or instrumentality thereof are used in financing the project, in whole or in part, or if a mortgage or mortgage bonds issued with respect to such project are insured by the federal government or any agency or instrumentality thereof.