(a) Except as provided by Subsection (b), if the only health benefit coverage offered under an employer's health benefit plan is a network-based delivery system of coverage offered by one or more health maintenance organizations, each health maintenance organization offering coverage must offer to all eligible employees, at the time of enrollment and at least annually, the opportunity to obtain coverage through a non-network plan.
(b) Each health maintenance organization to which Subsection (a) applies may enter into an agreement designating one or more of those health maintenance organizations to offer the coverage required by Subsection (a) for eligible employees of the employer.