of such security at any time during the 5-year period beginning on the date that such individual received such security— (1) the gross income of such individual for the taxable year which includes the date of such disposition shall be increased by the amount so excluded, and (2) the tax imposed by this chapter for such taxable year shall be increased by the sum of the amounts of tax which would have been imposed under subchapters A and B of chapters 21 and 22 if subsection (c) had not applied with respect to such amount. For purposes of this title and the Social Security Act, any increase in tax under paragraph (2) shall be treated as imposed under the provision of chapter 21 or 22 with respect to which such increase relates. (f) Basis of stock equal to fair market value at time of transfer Notwithstanding section 1012, in the case of a transfer of employer securities to which subsection (a)(1) applies, the basis of such securities in the hands of the transferee immediately after such transfer shall be equal to the fair market value of such securities (determined as of the time of such transfer). (g) Aggregation rule Two or more persons who are treated as a single employer under subsection (b), (c), (m), or (o) of section 414 shall be treated as a single employer for purposes of this section. (h) Election The election under subsection (a) shall be made at such time and in such manner as the Secretary may prescribe. Once made, such election may be revoked only with the consent of the Secretary. (i) Regulations The Secretary shall issue such regulations or other guidance as may be necessary or appropriate to carry out this section, including regulations or other guidance which— (1) provide for the application of this section to stock options, (2) provide mechanisms by which to satisfy the requirements of this section in the event that an employee is inadvertently excluded from a distribution of employer securities (including a case where a service provider is treated as not an employee by the employer, but is