Mich. Comp. Laws § 38.1432: Vesting.

Sec. 132.

A qualified participant is immediately 100% vested in his or her contributions made to Tier 2. 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%.