Request for withholding
A request that an annuity or any sick pay be subject to withholding under this chapter—
(A) shall be made by the payee in writing to the person making the payments and shall contain the social security number of the payee,
(B) shall specify the amount to be deducted and withheld from each full payment, and
(C) shall take effect— (i) in the case of sick pay, with respect to payments made more than 7 days after the date on which such request is furnished to the payor, or (ii) in the case of an annuity, at such time (after the date on which such request is furnished to the payor) as the Secretary shall by regulations prescribe.
Such a request may be changed or terminated by furnishing to the person making the payments a written statement of change or termination which shall take effect in the same manner as provided in subparagraph (C). At the election of the payor, any such request (or statement of change or revocation) may take effect earlier than as provided in subparagraph (C).