Code of Federal Regulations Title 5. Administrative Personnel § 5.1600.30 Accounts eligible for transfer

(a) A participant who has an open TSP account and is entitled to receive (or receives) an eligible rollover distribution, within the meaning of I.R.C. section 402(c)(4) (26 U.S.C. 402(c)(4)), from an eligible employer plan or a rollover contribution, within the meaning of I.R.C. section 408(d)(3) (26 U.S.C. 408(d)(3)), from a traditional IRA may transfer or roll over that distribution into his or her existing TSP account in accordance with § 1600.31.

(b) The only balances that the TSP will accept are balances that would otherwise be includible in gross income if the distribution were paid to the participant. The TSP will not accept any balances that have already been subjected to Federal income tax (after-tax monies) or balances from a uniformed services TSP account that will not be subject to Federal income tax (tax-exempt monies).

(c) Notwithstanding paragraph (b) of this section, the TSP will accept Roth funds that are transferred via trustee-to-trustee transfer from an eligible employer plan that maintains a qualified Roth contribution program described in section 402A of the Internal Revenue Code.

(d) The TSP will accept a transfer or rollover only to the extent the transfer or rollover is permitted by the Internal Revenue Code.