Mich. Comp. Laws § 38.65: Crediting years of service accrued.

Sec. 65.

A qualified participant who was a member, deferred member, or former nonvested member of Tier 1 shall be credited with the years of service accrued under Tier 1 on the effective date of participation in Tier 2 for the purpose of meeting the vesting requirements for benefits under section 64.