(a) A retiree, dependent, surviving spouse, or surviving dependent child who is not eligible to enroll in Medicare is eligible to enroll in a high deductible health plan offered under the group program, subject to any other applicable eligibility requirements, including requirements established by the trustee, but is not eligible to enroll in another health benefit plan offered under the group program.
(b) A retiree, dependent, surviving spouse, or surviving dependent child who is eligible to enroll in Medicare is eligible to enroll in a Medicare Advantage plan or a Medicare prescription drug plan offered under the group program, subject to any other applicable eligibility requirements, including requirements established by the trustee, but is not eligible to enroll in another health benefit plan offered under the group program unless authorized by Subsection (c).

(c) If the trustee makes another health benefit plan available under § 1575.158(d), any individual otherwise eligible under this section to enroll in a Medicare Advantage plan or Medicare prescription drug plan is eligible to enroll in that health benefit plan.