Applicability date. This section applies to foreign tax redeterminations occurring in taxable years ending on or after December 16, 2019, and to foreign tax redeterminations of foreign corporations occurring in taxable years that end with or within a taxable year of a United States shareholder ending on or after December 16, 2019.
26 CFR § 301.6689-1
Application of civil penalty. If a foreign tax redetermination occurs, and the taxpayer failed to notify the Internal Revenue Service (IRS) on or before the date and in the manner prescribed in 1.9054 of this chapter, or as required under section 404A(g)(2), for giving notice of a foreign tax redetermination, then, unless paragraph (d) of this section applies, there is added to the deficiency (or the imputed underpayment as determined under section 6225) attributable to such redetermination an amount determined under paragraph (b) of this section. Subchapter B of chapter 63 of the Internal Revenue Code (relating to deficiency proceedings) does not apply with respect to the assessment of the amount of the penalty.