Investment interest expense.
(i) Investment interest expense. Investment interest (as defined in section 163(d)(3)) to the extent allowed under section 163(d)(1). Any investment interest not allowed under section 163(d)(1) is treated as investment interest paid or accrued by the taxpayer in the succeeding taxable year. The following example illustrates the provisions of this paragraph. For purposes of this example, assume that the taxpayer uses a calendar taxable year, and Year 1 and all subsequent years are taxable years in which section 1411 is in effect: