851.44. Where at any time a taxpayer has paid an amount, in this section referred to as the “repaid amount”, on account of the principal amount of an indebtedness that was, before that time, the unpaid principal amount of a loan or any other form of indebtedness in respect of an expenditure of the taxpayer to which the first paragraph of section 851.39 applies, in this section referred to as the “former amount or benefit”, the following rules apply:(a) at all times before that time, the former amount or benefit is considered to have been an amount or benefit referred to in the first paragraph of section 851.39 in respect of the taxpayer; and
(b) subject to section 851.41, the expenditure is deemed to have been made or incurred at that time by the payment of, and to the extent of, the repaid amount.