(2)  Any representative assessee, or any person who apprehends that he may be assessed as a representative assessee, may retain out of any money payable by him to the person on whose behalf he is liable to pay tax (hereinafter in this section referred to as the principal), a sum equal to his estimated liability under this Chapter, and in the event of any disagreement between the principal and such representative assessee or person as to the amount to be so retained, such representative assessee or person may secure from the Assessing Officer a certificate stating the amount to be so retained pending final settlement of the liability, and the certificate so obtained shall be his warrant for retaining that amount.

(3)  The amount recoverable from such representative assessee or person at the time of final settlement shall not exceed the amount specified in such certificate, except to the extent to which such representative assessee or person may at such time have in his hands additional assets of the principal.