(a) Compliance in form and operation. An eligible plan is a written plan established and maintained by an eligible employer that is maintained, in both form and operation, in accordance with the requirements of §§ 1.457-4 through 1.457-10. An eligible plan must contain all the material terms and conditions for benefits under the plan. An eligible plan may contain certain optional features not required for plan eligibility under section 457(b), such as distributions for unforeseeable emergencies, loans, plan-to-plan transfers, additional deferral elections, acceptance of rollovers to the plan, and distributions of smaller accounts to eligible participants. However, except as otherwise specifically provided in §§ 1.457-4 through 1.457-10, if an eligible plan contains any optional provisions, the optional provisions must meet, in both form and operation, the relevant requirements under section 457 and §§ 1.457-2 through 1.457-10.

(b) Treatment as single plan. In any case in which multiple plans are used to avoid or evade the requirements of §§ 1.457-4 through 1.457-10, the Commissioner may apply the rules under §§ 1.457-4 through 1.457-10 as if the plans were a single plan. See also § 1.457-4(c)(3)(v) (requiring an eligible employer to have no more than one normal retirement age for each participant under all of the eligible plans it sponsors), the second sentence of § 1.457-4(e)(2) (treating deferrals under all eligible plans under which an individual participates by virtue of his or her relationship with a single employer as a single plan for purposes of determining excess deferrals), and § 1.457-5 (combining annual deferrals under all eligible plans).