1. Upon the completion of a development, a redevelopment corporation shall, or upon the completion of a principal part of a development, a redevelopment corporation may, file with the supervising agency an audited statement of the development cost thereof. Within a reasonable time after the filing of such statement, the supervising agency shall determine the development cost applicable to the development or such portion thereof and shall issue to the redevelopment corporation a certificate stating the amount thereof as so determined.

    2. A redevelopment corporation may, at any time, whether prior or subsequent to the undertaking of any contract or expense, apply to the supervising agency for a ruling as to whether any particular item of cost therein may be included in development cost when finally determined by the supervising agency, and the amount thereof. The supervising agency shall, within a reasonable time after such application, not to exceed 60 days, render a ruling thereon, and in the event that it shall be ruled that any item of cost may be included in development cost, or upon failure of the supervising agency to make such ruling within 60 days, the amount thereof as so determined shall be so included in development cost when finally determined.