§ 8431. Certain transfers to be treated as a separation
(a)
For purposes of this subchapter, separation from Government employment includes a transfer from a position that is subject to one of the retirement systems described in subsection (b) to a position that is not subject to any of them.
(b)
The retirement systems described in this subsection are—
(1)
the retirement system under this chapter;
(2)
the retirement system under subchapter III of chapter 83; and
(3)
any other retirement system under which individuals may contribute to the Thrift Savings Fund through withholdings from pay.