(1) A member or deferred vested member who meets the following requirements shall be entitled to a retirement allowance:

    (a) The member or deferred vested member qualifies under 1 of the following:

    (i) Has not less than 8 years of service.

    (ii) Has not less than 6 years of service, and has been elected, qualified, and seated not less than 4 times for full or partial terms if a member of the house or not less than 2 times if a member of the senate elected after November 7, 1966, or has not less than 6 years of service and has been elected, qualified, and seated not less than 2 times for full or partial terms as a member of the house and not less than 1 time as a member of the senate elected after November 7, 1966.

    (iii) Effective January 1, 1987, has not less than 5 years of service and has been elected, qualified, and seated for a full or partial term not less than 3 times if a member of the house or not less than 2 times if a member of the senate, or not less than 1 time as a member of the house and not less than 1 time as a member of the senate.

    (b) The member or deferred vested member has attained 55 years of age.

    (c) The member or deferred vested member has filed with the board a written application for a retirement allowance that states the years of service, the highest salary received during the member’s or deferred vested member’s service before application, and the date the member or deferred vested member desires to be retired, which date shall be not more than 90 days after the execution and filing of the application.

    (2) A member shall not be entitled to receive a retirement allowance provided for in this section or section 23d while serving as a legislator or lieutenant governor. Each person receiving benefits under this act consents and agrees as a condition of receiving the benefits that benefits of any nature shall not be paid while the person is a legislator or lieutenant governor.

    (3) A deferred vested member who left service after December 31, 1974, and before January 1, 1979, and who becomes a retirant shall be entitled to an annual retirement allowance of 30% of the salary stated in the application for the first 8 years of service plus 3.75% for each of the next 8 years of service. A fraction of a year of service in excess of 8 years shall be prorated. If the retirant has less than 8 years of service but qualifies by the election method, the retirement allowance shall be that proportion of 30% that his or her years of service and fraction of a year of service bears to 8 years. Years of service listed in the application need not be consecutive but shall have been rendered before payment of the retirement allowance. Except as provided in section 23c, a retirement allowance shall not exceed 60% of the salary stated in the application.

    (4) A member who retired after December 31, 1978 and before January 1, 1987, or a deferred vested member who left service after December 31, 1978 and before January 1, 1987, and becomes a retirant, shall be entitled to an annual retirement allowance of 32% of the salary stated in his or her application for the first 8 years of service plus 4% for each of the next 8 years of service. A fraction of a year of service in excess of 8 years shall be prorated. If the member or deferred vested member has less than 8 years of service but qualifies by the election method, the retirement allowance shall be that proportion of 32% that his or her years of service and fraction of a year of service bears to 8 years. Years of service listed in the application need not be consecutive, but shall have been rendered before payment of the retirement allowance. Except as provided in section 23c, a retirement allowance shall not exceed 64% of the salary stated in the application.

    (5) A member who first becomes a member on or before January 1, 1995 and who retires after December 31, 1986, or a deferred vested member who first becomes a member on or before January 1, 1995, who leaves service after December 31, 1986, and who becomes a retirant, shall be entitled to an annual retirement allowance of 20% of the salary stated in his or her application for the first 5 years of service plus 4% for each of the next 11 years of service. A fraction of a year of service in excess of 5 years shall be prorated. Years of service listed in the application need not be consecutive, but shall have been rendered before payment of the retirement allowance. Except as provided in this subsection and section 23c, a retirement allowance shall not exceed 64% of the salary stated in the application. Effective January 1, 1987, however, a member who first becomes a member on or before January 1, 1995 and who has 16 or more years of service shall also be entitled to a longevity allowance of 1.0% of the member’s salary for each year of service beyond 16 years but, except as otherwise provided in this subsection, not to exceed 20 years. Except as provided in this subsection and section 23c, the retirement allowance of a member entitled to a longevity allowance under this subsection shall not exceed 68% of the salary stated in the application. Beginning January 1, 1989, a member who first becomes a member on or before January 1, 1995, who has 20 or more years of service, and who meets the age and service requirements or service requirements to be eligible to receive a retirement allowance under this act shall be entitled to a longevity allowance of 1.0% of the member’s salary for each year of service beyond 20 years.

    (6) A member who first becomes a member on or after January 2, 1995 and who becomes a retirant under this act is entitled to an annual retirement allowance equal to the product of the following:

    (a) The salary stated in his or her application.

    (b) Years and fraction of a year of service.

    (c) Three percent.

    (7) A retirant who elects to purchase military service credit pursuant to section 11(2) shall have his or her retirement allowance recalculated to include the military service credit purchased pursuant to that section. The first payment of the recalculated retirement allowance shall be made effective with the first check after the recalculation is made.

    (8) The retirement allowance of a retirant who, on January 1, 1987, satisfied the conditions required by section 9(3) shall have his or her retirement allowance recalculated to reflect the increase in salary for those years permitted by section 9(3) before the member became a retirant.

    (9) Within 30 days after becoming 55 years of age, a deferred vested member may elect to defer receipt of the retirement allowance to which the member is entitled under this act to a date certain, not to exceed 70-1/2 years of age. Except as otherwise provided in this subsection, at the date the member designates to begin receipt of his or her retirement allowance, the member’s retirement allowance shall be actuarially recomputed to reflect the member’s age and life expectancy at initial receipt of the deferred retirement allowance. Upon request of the deferred vested member who elects to begin receiving his or her retirement allowance, the retirement board may pay to the member a lump sum payment of an amount equal to the sum of the retirement allowance that was deferred pursuant to this subsection. The retirement board shall not actuarially recompute the member’s retirement allowance upon payment of a lump sum under this subsection. If a deferred vested member has elected to defer receipt of his or her retirement allowance under section 23(9)(a) and subsequently dies before retirement, 100% of his or her deferred benefit shall be paid in accordance with a beneficiary designation that the member shall have filed with the board.

    (10) Notwithstanding subsection (1), a member or deferred vested member may retire with a retirement allowance computed according to the applicable provisions of this section if all of the following apply:

    (a) The member or deferred vested member files a written application with the retirement board stating a date, not less than 30 nor more than 90 days after the execution and filing of the application, on which the member or deferred vested member desires to retire.

    (b) On the last day of the month immediately preceding the retirement allowance effective date stated in the application, the member’s or deferred vested member’s combined age and length of credited service is equal to or greater than 70 years and the member or deferred vested member is 50 years of age or older.

    (11) A member who retires before January 1, 1987 or a deferred vested member who leaves service before January 1, 1987 and becomes a retirant shall, in addition to the retirement allowance calculated under subsection (3) or (4), be entitled to a longevity allowance if the retirant or deferred vested member has more than 16 years of service. The longevity allowance is 1.0% of the former member’s salary stated in the application for each year of service beyond 16 years but, except as otherwise provided in this subsection, not to exceed 20. A member who retires before January 1, 1987 or a deferred vested member who leaves service before January 1, 1987 and becomes a retirant shall, in addition to the retirement allowance calculated under subsection (3) or (4), be entitled to a longevity allowance of 1.0% of the former member’s salary stated in the application for each year of service beyond 20 years that was served after the member met the age and service requirements or service requirements to be eligible to receive a retirement allowance under this act. The retirement allowance of a retirant who satisfies the conditions under this subsection shall have his or her retirement allowance recalculated to reflect the longevity allowance for those years permitted by this subsection effective January 1, 1987 or the date of retirement, whichever is later. The application of the longevity allowance to the retirant’s retirement allowance under this subsection shall be applied before the provisions of section 23c are applied to that retirement allowance. Except as provided in this subsection and section 23c, a retirement allowance shall not exceed 68% of the salary stated in the application.