Treas. Reg. § 1.403(b)-8

(b) Contributions to the plan. Contributions to a section 403(b) plan must be transferred to the insurance company issuing the annuity contract (or the entity holding assets of any custodial or retirement income account that is treated as an annuity contract) within a period that is not longer than is reasonable for the proper administration of the plan. For purposes of this requirement, the plan may provide for section 403(b) elective deferrals for a participant under the plan to be transferred to the annuity contract within a specified period after the date the amounts would otherwise have been paid to the participant. For example, the plan could provide for section 403(b) elective deferrals under the plan to be contributed within 15 business days following the month in which these amounts would otherwise have been paid to the participant.

(1) Generally. As defined in § 1.403(b)-2, and except as otherwise permitted under this section, an annuity contract means a contract that is issued by an insurance company qualified to issue annuities in a State and that includes payment in the form of an annuity. This paragraph (c) sets forth additional rules regarding annuity contracts.

(2) Certain insurance contracts. Neither a life insurance contract, as defined in section 7702, an endowment contract, a health or accident insurance contract, nor a property, casualty, or liability insurance contract meets the definition of an annuity contract. See § 1.401(f)-4(e). If a contract issued by an insurance company qualified to issue annuities in a State provides death benefits as part of the contract, then that coverage is permitted, assuming that those death benefits do not cause the contract to fail to satisfy any requirement applicable to section 403(b) contracts, for example, assuming that those benefits satisfy the incidental benefit requirement of § 1.401-1(b)(1)(i), as required by § 1.403(b)-6(g).

(3) Special rule for certain contracts. This paragraph (c)(3) applies in the case of a contract issued under a State section 403(b) plan established on or before May 17, 1982, or for an employee who becomes covered for the first time under the plan after May 17, 1982, unless the Commissioner had before that date issued any written communication (either to the employer or financial institution) to the effect that the arrangement under which the contract was issued did not meet the requirements of section 403(b). The requirement that the contract be issued by an insurance company qualified to issue annuities in a State does not apply to a contract described in the preceding sentence if one of the following two conditions is satisfied and that condition has been satisfied continuously since May 17, 1982—

(i) Benefits under the contract are provided from a separately funded retirement reserve that is subject to supervision of the State insurance department; or

(ii) Benefits under the contract are provided from a fund that is separate from the fund used to provide statutory benefits payable under a state retirement system and that is part of a State teachers retirement system (including a state university retirement system) to purchase benefits that are unrelated to the basic benefits provided under the retirement system, and the death benefit provided under the contract does not at any time exceed the larger of the reserve or the contribution made for the employee.

(d) Custodial accounts

(1) Treatment as a section 403(b) contract. Under section 403(b)(7), a custodial account is treated as an annuity contract for purposes of §§ 1.403(b)-1 through 1.403(b)-7, this section and §§ 1.403(b)-9 through 1.403(b)-11. See section 403(b)(7)(B) for special rules regarding the tax treatment of custodial accounts and section 4973(c) for an excise tax that applies to excess contributions to a custodial account.

(2) Custodial account defined. A custodial account means a plan, or a separate account under a plan, in which an amount attributable to section 403(b) contributions (or amounts rolled over to a section 403(b) contract, as described in § 1.403(b)-10(d)) is held by a bank or a person who satisfies the conditions in section 401(f)(2), if—

(i) All of the amounts held in the account are invested in stock of a regulated investment company (as defined in section 851(a) relating to mutual funds);

(ii) The requirements of § 1.403(b)-6(c) (imposing restrictions on distributions with respect to a custodial account) are satisfied with respect to the amounts held in the account;

(iii) The assets held in the account cannot be used for, or diverted to, purposes other than for the exclusive benefit of plan participants or their beneficiaries (for which purpose, assets are treated as diverted to the employer if the employer borrows assets from the account); and

(iv) The account is not part of a retirement income account.

(3) Effect of definition. The requirement in paragraph (d)(2)(i) of this section is not satisfied if the account includes any assets other than stock of a regulated investment company.

(4) Treatment of custodial account. A custodial account is treated as a section 401 qualified plan solely for purposes of subchapter F of subtitle A and subtitle F of the Internal Revenue Code with respect to amounts received by it (and income from investment thereof). This treatment only applies to a custodial account that constitutes a section 403(b) contract under §§ 1.403(b)-1 through 1.403(b)-7, this section and §§ 1.403(b)-9 through 1.403(b)-11 or that would constitute a section 403(b) contract under §§ 1.403(b)-1 through 1.403(b)-7, this section and §§ 1.403(b)-9 through 1.403(b)-11 if the amounts held in the account were to satisfy the nonforfeitability requirement of § 1.403(b)-3(a)(2).

(e) Retirement income accounts. See § 1.403(b)-9 for special rules under which a retirement income account for employees of a church-related organization is treated as a section 403(b) contract for purposes of §§ 1.403(b)-1 through 1.403(b)-7, this section and §§ 1.403(b)-9 through 1.403(b)-11.

(f) Combining assets. To the extent permitted by the Commissioner in revenue rulings, notices, or other guidance published in the Internal Revenue Bulletin (see § 601.601(d)(2)(ii)(b) of this chapter), trust assets held under a custodial account and trust assets held under a retirement income account, as described in § 1.403(b)-9(a)(6), may be invested in a group trust with trust assets held under a qualified plan or individual retirement plan. For this purpose, a trust includes a custodial account that is treated as a trust under section 401(f).

Treas. Reg. § 1.403(b)-8

Funding.