(C) Method of discounting The present value under subparagraph (B) shall be determined— (i) as of the last day of the 1st year of the 15-year period referred to in subparagraph (B), (ii) by using a discount rate equal to 72 percent of the average of the annual Federal mid-term rate and the annual Federal long-term rate applicable under section 1274(d)(1) to the month applicable under clause (i) or (ii) of subparagraph (A) and compounded annually, and (iii) by assuming that the credit allowable under this section for any year is received on the last day of such year. (2) Minimum credit rate The applicable percentage for any building shall not be less than 5 percent. (3) Cross references (A) For treatment of certain rehabilitation expenditures as separate new buildings, see subsection (e). (B) For determination of applicable percentage for increases in qualified basis after the 1st year of the credit period, see subsection (f)(3). (C) For authority of housing credit agency to limit applicable percentage and qualified basis which may be taken into account under this section with respect to any building, see subsection (h)(6). (c) Qualified basis