deferral period
(4) Change in substantially equal payments (A) In general If— (i) paragraph (1) does not apply to a distribution by reason of paragraph (2)(A)(iv), and (ii) the series of payments under such paragraph are subsequently modified (other than by reason of death or disability or a distribution to which paragraph (10) applies)— (I) before the close of the 5-year period beginning with the date of the first payment and after the employee attains age 59½, or (II) before the employee attains age 59½, the taxpayer’s tax for the 1st taxable year in which such modification occurs shall be increased by an amount, determined under regulations, equal to the tax which (but for paragraph (2)(A)(iv)) would have been imposed, plus interest for the deferral period. (B) Deferral period For purposes of this paragraph, the term “deferral period” means the period beginning with the taxable year in which (without regard to paragraph (2)(A)(iv)) the distribution would have been includible in gross income and ending with the taxable year in which the modification described in subparagraph (A) occurs. (C) Rollovers to subsequent plan If— (i) payments described in paragraph (2)(A)(iv) are being made from a qualified retirement plan, (ii) a transfer or a rollover from such qualified retirement plan of all or a portion of the taxpayer’s benefit under the plan is made to another qualified retirement plan, and (iii) distributions from the transferor and transferee plans would in combination continue to satisfy the requirements of paragraph (2)(A)(iv) if they had been made only from the transferor plan, such transfer or rollover shall not be treated as a modification under subparagraph (A)(ii), and compliance with paragraph (2)(A)(iv) shall be determined on the basis of the combined distributions described in clause (iii).