In general

Enhanced voucher assistance under this subsection for a family shall be voucher assistance under subsection ( o ), except that under such enhanced voucher assistance—

(A) subject only to subparagraph (D), the assisted family shall pay as rent no less than the amount the family was paying on the date of the eligibility event for the project in which the family was residing on such date;

(B) the assisted family may elect to remain in the same project in which the family was residing on the date of the eligibility event for the project, and if, during any period the family makes such an election and continues to so reside, the rent for the dwelling unit of the family in such project exceeds the applicable payment standard established pursuant to subsection ( o ) for the unit, the amount of rental assistance provided on behalf of the family shall be determined using a payment standard that is equal to the rent for the dwelling unit (as such rent may be increased from time-to-time), subject to paragraph (10)(A) of subsection ( o ) and any other reasonable limit prescribed by the Secretary, except that a limit shall not be considered reasonable for purposes of this subparagraph if it adversely affects such assisted families;

(C) subparagraph (B) of this paragraph shall not apply and the payment standard for the dwelling unit occupied by the family shall be determined in accordance with subsection ( o ) if— (i) the assisted family moves, at any time, from such project; or (ii) the voucher is made available for use by any family other than the original family on behalf of whom the voucher was provided; and

(D) if the annual adjusted income of the assisted family declines to a significant extent, the percentage of annual adjusted income paid by the family for rent shall not exceed the greater of 30 percent or the percentage of annual adjusted income paid at the time of the eligibility event for the project.