of section 3121(a), but determined without regard to any dollar limitation contained in such section) paid to such officer or employee for services performed during the taxable year. In the case of any officer or employee who is not employed for the entire taxable year, the wages paid for such taxable year shall be increased by an amount equal to the product of the average daily wages paid to such employees for the number of days during the taxable year during which such employee was employed and the number of days during the taxable year during which such employee was not so employed. (e) Exceptions