taxable period
(1) Taxable period The term “taxable period” means, with respect to the undistributed income for any taxable year, the period beginning with the first day of the taxable year and ending on the earlier of— (A) the date of mailing of a notice of deficiency with respect to the tax imposed by subsection (a) under section 6212, or (B) the date on which the tax imposed by subsection (a) is assessed.