This excerpt taken from the EBAY 10-K filed Feb 28, 2007.
As a condition of the Restricted Stock Units becoming vested and the Shares subject to the RSUs being delivered to Participant, Participant agrees to accept any liability for secondary Class 1 NICs (Employer NICs) which may be payable by the Company or Participants employer with respect to the vesting of the RSUs or otherwise payable in respect of a benefit derived in connection with the RSUs. To accomplish the foregoing, Participant agrees to execute a joint election between the Company and/or Participants employer and Participant (the Election), the form of such Election being formally approved by HM Revenue and Customs, and any other consent or elections required to accomplish the transfer of the Employer NICs to Participant. Participant further agrees to execute such other joint elections as may be required between Participant and any successor to the Company and/or Participants employer. If Participant does not enter into an Election prior to the first vesting date, the RSUs shall cease vesting and shall become null and void without any liability to the Company and/or Participants employer. Participant further agrees that the Company and/or Participants employer may collect the Employer NICs from Participant by any of the means set forth above.