(1) A qualified participant is immediately 100% vested in his or her contributions made to Tier 2 and employer contributions under the banked leave time program. Except as otherwise provided in this section, a qualified participant shall vest in the employer contributions made on his or her behalf to Tier 2 according to the following schedule:

  (a) Upon completion of 2 years of service, 50%.

  (b) Upon completion of 3 years of service, 75%.

  (c) Upon completion of 4 years of service, 100%.

  (2) A qualified participant is eligible for the health insurance coverage provided in section 68 if the qualified participant meets 1 of the following requirements:

  (a) The qualified participant has completed 10 years of service as a qualified participant, was not a member, deferred member, or former nonvested member of Tier 1, was first employed and entered upon the payroll of his or her employer before January 1, 2012, and did not make an election to opt out of health insurance coverage under section 68b.

  (b) The qualified participant was a member, deferred member, or former nonvested member of Tier 1 who made an election to participate in Tier 2 pursuant to section 50, and who has met the service requirements he or she would have been required to meet in order to vest in health benefits under section 20d.