Reg. § 54.4971-1 General rules relating to excise tax on failure to meet minimum funding standards.
(a)-(b) [Reserved]
(c) Additional tax Section imposes an excise tax in any case in which an initial tax is imposed under section on an accumulated funding deficiency and the accumulated funding deficiency is not corrected within the taxable period (as defined in section ). The additional tax is 100 percent of the accumulated funding deficiency to the extent not corrected.
(d) [Reserved]
(e) Definition of taxable period
(1) In general For purposes of any accumulated funding deficiency, the term “taxable period” means the period beginning with the end of the plan year in which there is an accumulated funding deficiency and ending on the earlier of:
(i) The date of mailing of a notice of deficiency under section with respect to the tax imposed by section , or
(ii) The date on which the tax imposed by section is assessed.
(2) Special rule Where a notice of deficiency referred to in of this section is not mailed because a waiver of the restrictions on assessment and collection of a deficiency has been accepted or because the deficiency is paid, the date of filing of the waiver or the date of such payment, respectively, shall be treated as the end of the taxable period.
[T.D. 8084, 51 FR 16305, May 2, 1986]