outstanding deferral stock. (iv) Reporting Any corporation which has outstanding deferral stock as of the beginning of any calendar year and which purchases any of its outstanding stock during such calendar year shall include on its return of tax for the taxable year in which, or with which, such calendar year ends the total dollar amount of its outstanding stock so purchased during such calendar year and such other information as the Secretary requires for purposes of administering this paragraph. (5) Controlled groups For purposes of this subsection, all persons treated as a single employer under section 414(b) shall be treated as 1 corporation. (6) Notice requirement Any corporation which transfers qualified stock to a qualified employee shall, at the time that (or a reasonable period before) an amount attributable to such stock would (but for this subsection) first be includible in the gross income of such employee— (A) certify to such employee that such stock is qualified stock, and (B) notify such employee— (i) that the employee may be eligible to elect to defer income on such stock under this subsection, and (ii) that, if the employee makes such an election— (I) the amount of income recognized at the end of the deferral period will be based on the value of the stock at the time at which the rights of the employee in such stock first become transferable or not subject to substantial risk of forfeiture, notwithstanding whether the value of the stock has declined during the deferral period, (II) the amount of such income recognized at the end of the deferral period will be subject to withholding under section 3401(i) at the rate determined under section 3402(t), and (III) the responsibilities of the employee (as determined by the Secretary under paragraph (3)(A)(ii)) with respect to such withholding. (7) Restricted stock units This section (other than this subsection), including any election under subsection (b), shall not apply to restricted stock units. . (b) Withholding (1) Time of withholding Section