(b) A voluntary incentive payment—
(1) shall be offered to agency employees on the basis of—
(E)
specific periods of time during which eligible employees may elect a voluntary incentive payment; or
(3) shall be equal to the lesser of—
(A)
an amount equal to the amount the employee would be entitled to receive under section 5595(c) if the employee were entitled to payment under such section (without adjustment for any previous payment made); or
(4)
may be made only in the case of an employee who voluntarily separates (whether by retirement or resignation) under this subchapter;
(5)
shall not be a basis for payment, and shall not be included in the computation, of any other type of Government benefit;
(7)
shall be paid from appropriations or funds available for the payment of the basic pay of the employee.