(1) Until September 29, 2017 at 5 p.m. Eastern Daylight Saving Time, the retirement board shall grant service credit for the time a member is on a sabbatical leave authorized by a reporting unit, if the member returns to regular employment with the same reporting unit and acquires 1 year or more of subsequent service credit with that same reporting unit and if the member acquired 5 or more years of credited service with the reporting unit immediately before the sabbatical leave.

  (2) If the sabbatical leave described in subsection (1) is granted before July 1, 1981, the reporting unit, if the reporting unit had a noncontributory plan at the time the sabbatical leave is granted, or the member, if the reporting unit has a contributory plan at the time the sabbatical leave is granted, shall pay to the system for each year of sabbatical leave credit an amount equal to 5% of the member’s compensation earned in the school fiscal year immediately before the school fiscal year in which the sabbatical leave is granted, together with regular interest from the end of the school fiscal year in which the sabbatical leave was or is granted to the earlier of the following dates following the date of payment, the first day of the school fiscal year beginning after the date of payment or the first day of the seventh month of the school fiscal year in which the payment is made. If the reporting unit makes the payment required by this subsection, the reporting unit also shall pay the required interest. If the member makes the payment required by this subsection, the member also shall pay the required interest.

  (3) If the sabbatical leave described in subsection (1) is granted after June 30, 1981, the member shall pay an amount equal to 5% of the member’s full-time or equated full-time compensation earned in the school fiscal year immediately before the school fiscal year in which payment is made for each year of service credit the member elects to purchase. In computing payment under this subsection, the compensation amount used, except as otherwise provided in this subsection, must not be less than the highest school fiscal year compensation the member earned from the reporting unit that granted the sabbatical leave. If the compensation amount used for computing payment under this subsection exceeds the member’s final average compensation determined at the time of retirement, the payment required under this subsection must be recomputed using the member’s final average compensation and a refund must be made based on the recomputation.

  (4) If, before October 31, 1980, either the reporting unit or the member has contributed 5% of the member’s compensation for the school fiscal year in which the sabbatical leave was granted in order to purchase service credit for that sabbatical leave, a further payment for the purchase of service credit for that sabbatical leave shall not be required. If a member has paid the amount required under subsection (2) for the purchase of service credit for sabbatical leave, but later receives a refund of that amount, the member, not the reporting unit, shall repay the amount with regular interest as required by subsection (2) if the member elects to purchase service credit for the sabbatical leave.

  (5) Effective October 1, 1981, the retirement board shall grant service credit for the time a member is on either an employee organization professional services leave or employee organization professional services released time authorized by a reporting unit if all of the following conditions are satisfied, as applicable:

  (a) For a member who is on either a professional services leave or professional services released time that first began before October 1, 1996, which leave or released time is renewed annually by the reporting unit, the member is included on the reporting unit’s reports required by section 42(6) and compensation, service, contribution, and other requirements are reported on the same basis as for those members of the reporting unit who were not granted an employee organization professional services leave or employee organization professional services released time.

  (b) For a member who is on either a professional services leave or professional services released time, which leave or released time does not meet the requirements of subdivision (a), the member is included on the reporting unit’s reports in the manner required by subdivision (a), except that compensation is reported at the rate of compensation paid to the member by the reporting unit immediately preceding the date the member commenced the professional services leave or professional services released time along with the normal and customary compensation increases that would have been paid to the member by the reporting unit had the member remained in the same position held at the reporting unit immediately preceding the date the member commenced the leave or released time. However, if the member was not working a full 12-month period for the reporting unit immediately preceding the date the member commenced the professional services leave or professional services released time and is working a full 12-month period for the public school employee organization, the rate of compensation paid to the member by the reporting unit immediately preceding the date the member commenced the leave or released time may be increased proportionately to reflect the additional time worked for the public school employee organization. That adjusted compensation, along with the normal and customary compensation increases otherwise allowed in this subdivision, must then be reported as required in this subdivision.

  (c) For a member who is on either a professional services leave or professional services released time that first began before October 1, 1996, which leave or released time is renewed annually by the reporting unit, the reporting unit remits the amount required by section 42 and the percentage of aggregate annual compensation provided from the state school aid fund for current service, if any, the percentage determined for unfunded accrued service as required by section 41, and the employer’s share of social security contributions if the reporting unit is responsible for remitting the employee’s share of social security contributions.

  (d) For a member who is on either a professional services leave or professional services released time, which professional services leave or professional services released time does not meet the requirements of subdivision (c), the reporting unit remits the amounts required by subdivision (c) based on the rate of compensation paid to the member by the reporting unit immediately preceding the date the member commenced the professional services leave or professional services released time along with the normal and customary compensation increases that would have been paid to the member by the reporting unit had the member remained in the same position held at the reporting unit immediately preceding the date the member commenced the leave or released time. However, if the member was not working a full 12-month period for the reporting unit immediately preceding the date the member commenced the professional services leave or professional services released time and is working a full 12-month period for the public school employee organization, the rate of compensation paid to the member by the reporting unit immediately preceding the date the member commenced the leave or released time may be increased proportionately to reflect the additional time worked for the public school employee organization. That adjusted compensation, along with the normal and customary compensation increases otherwise allowed in this subdivision, must then be reported as required in this subdivision.

  (6) The reporting unit must be reimbursed those sums paid to the retirement board under subsection (5) by the member or the public school employee organization on a current basis. A member who has credited service as an employee of a school district of the first class, as described in part 6 of the revised school code, 1976 PA 451, MCL 380.401 to 380.485, for a leave of absence effective before October 1, 1981, shall continue to receive credit based on the law of this state in effect at the time the leave of absence was initially effective.

  (7) After September 29, 2017 at 5 p.m. Eastern Daylight Saving Time, a member is not eligible to initiate a service credit purchase under subsections (1) and (3).