has the meaning given such term under section 3121(a), determined without regard to paragraph (1) thereof. (B) Exception Such term shall not include any wages taken into account under sections 41, 45A, 45P, 45S, 51, and 1396. (4) Other terms Any term used in this section which is also used in this chapter shall have the same meaning as when used in this chapter. (d) Aggregation rule All persons treated as a single employer under subsection (a) or (b) of section 52, or subsection (m) or (o) of section 414, shall be treated as one employer for purposes of this section. (e) Election To not take certain wages into account This section shall not apply to so much of the wages paid by an eligible employer as such employer elects (at such time and in such manner as the Secretary may prescribe) to not take into account for purposes of this section. (f) Third party payors Any credit allowed under this section shall be treated as a credit described in section 3511(d)(2). (g) Treatment of deposits The Secretary shall waive any penalty under section 6656 for any failure to make a deposit of any applicable employment taxes if the Secretary determines that such failure was due to the reasonable anticipation of the credit allowed under this section. (h) Extension of limitation on assessment Notwithstanding section 6501, the limitation on the time period for the assessment of any amount attributable to a credit claimed under this section shall not expire before the date that is 5 years after the later of— (1) the date on which the original return which includes the calendar quarter with respect to which such credit is determined is filed, or (2) the date on which such return is treated as filed under section 6501(b)(2). (i) Regulations and guidance The Secretary shall issue such forms, instructions, regulations, and other guidance as are necessary— (1) with respect to the application of the credit under subsection (a) to third party payors (including professional employer organizations, certified professional employer