; and (ii) not to be less than $25; (B) the Secretary adjusts the calculated monthly payment under subparagraph (A), if— (i) in addition to the loans described in subparagraph (A), the borrower has an outstanding loan made under part B or D (other than an excepted parent loan or an excepted consolidation loan, as such terms are defined in section 493C(a)), by determining the borrower’s adjusted monthly payment by multiplying— (I) the calculated monthly payment, by (II) the percentage of the total outstanding principal amount of the borrower’s loans described in the matter preceding subclause (I), which are described in subparagraph (A); (ii) the borrower and borrower’s spouse have loans described in subparagraph (A) and outstanding loans under part B or D (other than an excepted parent loan or an excepted consolidation loan, as such terms are defined in section 493C(a)) and have filed a joint or separate Federal income tax return, in which case the Secretary determines— (I) each borrower’s percentage of the couple’s total outstanding amount of principal on such loans; (II) the adjusted monthly payment for each borrower by multiplying the borrower’s calculated monthly payment by the percentage determined under subclause (I) applicable to the borrower; and (III) if the borrower’s loans are held by multiple holders, the borrower’s adjusted monthly payment for loans described in subparagraph (A) by multiplying the adjusted monthly payment determined under subclause (II) by the percentage of the total outstanding principal amount of the borrower’s loans described in the matter preceding subclause (I), which are described in subparagraph (A); (C) the holder of such a loan shall apply the borrower’s monthly payment under this subsection first toward interest due on the loan, next toward any fees due on the loan, and then toward the principal of the loan; (D) any principal due and not paid under subparagraph (C) shall be deferred