Tier 2 accounts are subject to the following terms and conditions:

  (a) On or before January 1, 2013, the retirement system shall design an automatic enrollment feature that provides that unless a qualified participant who makes contributions under this act elects to contribute a lesser amount, the qualified participant shall contribute the amount required to qualify for all eligible matching contributions under this act. The retirement system shall implement this automatic enrollment feature on or after January 1, 2013, as determined by the retirement system.

  (b) Employer matching contributions do not have to be made to the same plan or account to which the elective employee contributions were contributed as the basis for the matching contributions.

  (c) Elective employee contributions shall not be used as the basis for more than an equivalent amount of employer matching contributions or, in the case of matching contributions under section 131(2), 50% of the employer matching contributions.

  (d) The retirement system shall design and implement a method to determine the proper allocation of employer matching contributions based on elective employee contributions as provided in this section.