In general
The term “disqualified portion” means, with respect to any covered asset acquisition, for any taxable year, the ratio (expressed as a percentage) of—
(i)#
the aggregate basis differences (but not below zero) allocable to such taxable year under subparagraph (B) with respect to all relevant foreign assets, divided by
(ii)#
the income on which the foreign income tax referred to in paragraph (1) is determined (or, if the taxpayer fails to substantiate such income to the satisfaction of the Secretary, such income shall be determined by dividing the amount of such foreign income tax by the highest marginal tax rate applicable to such income in the relevant jurisdiction).