voluntary repayment
(6) (A) For purposes of paragraph (2), any voluntary repayment shall be applied against advances made under section 1321 of this title on the last made first repaid basis. Any other repayment of such an advance shall be applied against advances on a first made first repaid basis. (B) For purposes of this paragraph, the term “voluntary repayment” means any repayment made under subsection (a).