24 C.F.R. § 888.320
(a) Determining the amount of the new Contract Rent. Project owners eligible for retroactive payments, as described in § 888.301(c), may request a one-time Contract Rent determination, to be effective as described in paragraph (c) of this section. The request for a one-time rent determination must be made when submitting a request for retroactive payments, as described in § 888.315. If no claim for retroactive payments is made, an owner may submit only the request for a one-time rent determination, provided the owner is eligible for retroactive payments. The new Contract Rent under this provision will be the greater of:
(c) Effective date of new Contract Rent. The new Contract Rent, determined under paragraph (a) of this section, will be effective on May 31, 1991.
(Approved by the Office of Management and Budget under control number 2505-0042)