For purposes of paragraph (1)(B)(i), the interest determined under this paragraph for any taxable year is the amount of interest at the underpayment rate under section 6621 plus 1 percentage point on the underpayments that would have occurred had the deferred compensation been includible in gross income for the taxable year in which first deferred or, if later, the first taxable year in which such deferred compensation is not subject to a substantial risk of forfeiture.
To the extent provided in regulations prescribed by the Secretary, if compensation is determined solely by reference to the amount of gain recognized on the disposition of an investment asset, such compensation shall be treated as subject to a substantial risk of forfeiture until the date of such disposition.
Paragraph (3)(B) shall not apply to any compensation to which clause (i) applies.
Compensation shall not be treated as deferred for purposes of this section if the service provider receives payment of such compensation not later than 12 months after the end of the taxable year of the service recipient during which the right to the payment of such compensation is no longer subject to a substantial risk of forfeiture.
In the case of a foreign corporation with income which is taxable under section 882, this section shall not apply to compensation which, had such compensation been paid in cash on the date that such compensation ceased to be subject to a substantial risk of forfeiture, would have been deductible by such foreign corporation against such income.
The Secretary shall prescribe such regulations as may be necessary or appropriate to carry out the purposes of this section, including regulations disregarding a substantial risk of forfeiture in cases where necessary to carry out the purposes of this section.