during the taxable year in connection with the active conduct of a trade or business within a possession of the United States to any employee for services performed in such possession, but only if such services are performed while the principal place of employment of such employee is within such possession. (B) Limitation on amount of wages taken into account (i) In general The amount of wages which may be taken into account under subparagraph (A) with respect to any employee for any taxable year shall not exceed the contribution and benefit base determined under section 230 of the Social Security Act for the calendar year in which such taxable year begins. (ii) Treatment of part-time employees, etc If— (I) any employee is not employed by the qualified corporation on a substantially full-time basis at all times during the taxable year, or (II) the principal place of employment of any employee with the qualified corporation is not within a possession at all times during the taxable year, the limitation applicable under clause (i) with respect to such employee shall be the appropriate portion (as determined by the Secretary) of the limitation which would otherwise be in effect under clause (i). (C) Treatment of certain employees The term qualified possession wages shall not include any wages paid to employees who are assigned by the employer to perform services for another person, unless the principal trade or business of the employer is to make employees available for temporary periods to other persons in return for compensation. All qualified corporations treated as 1 corporation under subsection (f)(1) shall be treated as 1 employer for purposes of the preceding sentence. (D) Wages (i) In general Except as provided in clause (ii), the term wages has the meaning given to such term by subsection (b) of section 3306 (determined without regard to any dollar limitation contained in such section). For purposes of the preceding sentence, such subsection (b) shall be applied as if the term United States included all