1. Annuity payments to retired employees under the provisions of sections 56.800 to 56.840 shall be available beginning January first next succeeding the expiration of two calendar years from the effective date of the establishment of the system to eligible retired employees, and employees with at least twelve years of creditable service shall have vested rights and upon reaching the required age shall be entitled to retirement benefits.

2. All members serving as a prosecuting attorney or circuit attorney in a county of the first classification, a county with a charter form of government, or a city not within a county shall receive one year of creditable service for each year served.

3. Notwithstanding any provision of law to the contrary, members serving as a prosecuting attorney in counties that elected to make the position of prosecuting attorney a full-time position shall receive one year of creditable vesting service for each year served as a part-time or full-time prosecuting attorney. Such members shall receive one year of creditable benefit service for each year served as a full-time prosecuting attorney and six-tenths of a year of creditable benefit service for each year served as a part-time prosecuting attorney. Upon retirement, any member who has less than twelve years of creditable benefit service shall receive a reduced full-time benefit in a sum equal to the portion that the member’s creditable benefit years bear to twelve vesting years.

4. Members restoring creditable service under subsection 2 of section 56.833 shall receive one year of creditable service for each restored year served as a full-time prosecuting attorney and six-tenths of a year of creditable service for each restored year served as a part-time prosecuting attorney. Unless otherwise permitted by law, no member shall receive credit for any partial year of employment.

5. Notwithstanding any provision of law to the contrary, any member who vested in the system as a part-time prosecuting attorney and who ceased being a member for more than six months before returning as a full-time prosecuting attorney shall be entitled only to retirement benefits as a part-time prosecuting attorney. Any creditable service earned by such an employee upon returning to the system as a full-time prosecuting attorney shall begin a new vesting period subject to the provision of the system in effect at the time of the member’s return. No member shall receive benefits while employed as a prosecuting attorney or circuit attorney.