(a) If a portion of the remuneration paid by an employer to his employee for services performed during a payroll period of not more than 31 consecutive days constitutes wages, and the remainder does not constitute wages, all the remuneration paid the employee for services performed during such period shall for purposes of withholding be treated alike, that is, either all included as wages or all excluded. The time during which the employee performs services, the remuneration for which under section 3401(a) constitutes wages, and the time during which he performs services, the remuneration for which under such section does not constitute wages, determine whether all the remuneration for services performed during the payroll period shall be deemed to be included or excluded.
(b) If one-half or more of the employee's time in the employ of a particular employer in a payroll period is spent in performing services the remuneration for which consititutes wages, then all the remuneration paid the employee for services performed in that payroll period shall be deemed to be wages.
(c) If less than one-half of the employee's time in the employ of a particular employer in a payroll period is spent in performing services the remuneration for which constitutes wages, then none of the remuneration paid the employee for services performed in that payroll period shall be deemed to be wages.
(d) The application of the provisions of paragraphs (a), (b), and (c) of this section may be illustrated by the following examples:
(e) The rules set forth in this section do not apply (1) with respect to any remuneration paid for services performed by an employee for his employer if the periods for which remuneration is paid by the employer vary to the extent that there is no period which constitutes a payroll period within the meaning of section 3401(b) (see §31.3401(b)-1), or (2) with respect to any remuneration paid for services performed by an employee for his employer if the payroll period for which remuneration is paid exceeds 31 consecutive days. In any such case withholding is required with respect to that portion of such remuneration which constitutes wages.