In this section, “eligible employee” means: a participant under the group health benefit plan; or an individual who: has met any waiting period applicable to becoming a participant under the group health benefit plan; is eligible to be enrolled under the plan; and is not a participant in the group health benefit plan because of failure to enroll during a previous enrollment period. This section applies if a group health benefit plan makes coverage available to dependents of an eligible employee. A group health benefit plan subject to this section shall provide a special enrollment period during which the following individuals may be enrolled under the group health benefit plan: an individual who becomes a dependent of an eligible employee through marriage, birth, adoption, or placement for adoption; an eligible employee who acquires a new dependent through marriage, birth, adoption, or placement for adoption; and the spouse of an eligible employee at the birth or adoption of a child, provided the spouse is otherwise eligible for coverage. An eligible employee may not enroll a dependent during a special enrollment period unless the eligible employee: is enrolled under the health benefit plan; or applies for coverage for the eligible employee during the same special enrollment period. The special enrollment period under subsection (c) of this section shall be a period of not less than 31 days and shall begin on the later of: the date dependent coverage is made available; or the date of the marriage, birth, adoption, or placement for adoption, whichever is applicable. If an eligible employee enrolls any of the individuals described in subsection (c) of this section during the first 31 days of the special enrollment period, the coverage shall become effective as follows: in the case of marriage, not later than the first day of the first month beginning after the date the completed request for enrollment is received; in the case of a dependent’s birth, as of the date of the dependent’s birth; and in the case of a dependent’s adoption or placement for adoption, the date of adoption or placement for adoption, whichever occurs first.