26 CFR §1.453-12

1. (a)General rule. Unrecaptured section 1250 gain, as defined in section 1(h)(7), is reported on the installment method if that method otherwise applies under section 453 or 453A and the corresponding regulations. If gain from an installment sale includes unrecaptured section 1250 gain and adjusted net capital gain (as defined in section 1(h)(4)), the unrecaptured section 1250 gain is taken into account before the adjusted net capital gain.
2. (b)Installment payments from sales before May 7, 1997. The amount of unrecaptured section 1250 gain in an installment payment that is properly taken into account after May 6, 1997, from a sale before May 7, 1997, is determined as if, for all payments properly taken into account after the date of sale but before May 7, 1997, unrecaptured section 1250 gain had been taken into account before adjusted net capital gain.
3. (c)Installment payments received after May 6, 1997, and on or before August 23, 1999. If the amount of unrecaptured section 1250 gain in an installment payment that is properly taken into account after May 6, 1997, and on or before August 23, 1999, is less than the amount that would have been taken into account under this section, the lesser amount is used to determine the amount of unrecaptured section 1250 gain that remains to be taken into account.
4. (d)Examples. In each example, the taxpayer, an individual whose taxable year is the calendar year, does not elect out of the installment method. The installment obligation bears adequate stated interest, and the property sold is real property held in a trade or business that qualifies as both section 1231 property and section 1250 property. In all taxable years, the taxpayer's marginal tax rate on ordinary income is 28 percent. The following examples illustrate the rules of this section:
5. (e)Effective date. This section applies to installment payments properly taken into account after August 23, 1999.