Sec. 6. CREDITABLE SERVICE. (a) The retirement allowance of a member is based on the member's creditable service as of the member's actual retirement date.

(b) The retirement board shall determine by nondiscriminatory rules and regulations consistently applied, subject to the provisions of this Act, in case of absence, illness, or other temporary interruption in service as a regular full-time employee, the portion of each calendar year to be allowed as creditable service. No credit shall be allowed as creditable service for any period exceeding one month during which an employee was absent continuously without pay, except for an authorized leave of absence as provided in this Act. The retirement board shall verify the records for creditable service claims filed by the members of the retirement system, subject to the provisions of this Act and in accordance with such administrative rules and regulations as the retirement board may from time to time adopt.

(c)(1) Uniformed service creditable in the retirement system is any service required to be credited by the Uniformed Services Employment and Reemployment Rights Act of 1994 (38 U.S.C. Section 4301 et seq.), as amended, and certain federal duty service in the armed forces of the United States performed before the beginning of employment with the employer, other than service as a student at a service academy, as a member of the reserves, or any continuous active military service lasting less than 90 days. A member may use uniformed service to establish creditable service subject to the conditions of Subdivisions (2)-(6) of this subsection.

(2) A member may establish uniformed creditable service for an authorized leave of absence from employment for military service under this subsection by making periodic payments or a lump-sum payment. If the member elects to make periodic payments, the member shall make, each pay period during the period that the member is on authorized leave, a deposit in an amount equal to the amount of the member's deposit for the last complete pay period that the member was paid by the employer as a regular full-time employee. If the member elects to make a lump-sum payment, the member and the employer shall, not later than the fifth anniversary of the date the member returns to employment with the employer, make separate lump-sum payments equal to the total amount of the contributions the member would have made if the member had made periodic contributions. A lump-sum payment may not exceed the amount required under the Uniformed Services Employment and Reemployment Rights Act of 1994 (38 U.S.C. Section 4301 et seq.), as amended, if the member makes the contributions within the time required by that Act. The employee's employer shall make contributions to the retirement fund as though the member has continued employment at the salary of the member for the last complete pay period before the absence for military service. The employer's contributions shall be made each pay period if the member is making periodic payments during the period. During an authorized leave of absence, the member accrues membership service for the pay periods in which the member makes a deposit. Membership service credit for a lump-sum payment accrues at the time of payment.

(3) A member may establish uniformed creditable service for active federal duty service in the armed forces of the United States, other than service as a student at a service academy, as a member of the reserves, or any continuous active military service lasting less than 90 days, performed before the first day of employment of the member's most recent membership in the retirement system or its predecessor system. To establish creditable service under this subdivision, the member must contribute a lump-sum payment equal to 25 percent of the estimated cost of the retirement benefits the member will be entitled to receive. The retirement board will determine the required contribution based on a procedure recommended by the actuary and approved by the retirement board.

(4) A member is not eligible to establish uniformed service credit unless the member was released from active military duty under conditions other than dishonorable.

(5) A member may not establish creditable service in the retirement system for uniformed service for more than the greater of the creditable service required under the Uniformed Services Employment and Reemployment Rights Act of 1994 (38 U.S.C. Section 4301 et seq.), as amended, or 48 months of creditable service in the retirement system for uniformed service under this subsection. A member is not precluded from purchasing qualified military service to which the member is entitled solely because the member, before beginning a leave of absence for qualified military service, purchased creditable service for military service performed before becoming employed by the employer.

(6) After the member makes the deposit required by this subsection, the retirement system shall grant the member one month of creditable service for each month of creditable uniformed service established under this subsection.

(d) At any time before the actual retirement date of a member, the employer of the member may purchase for the member additional creditable service that shall be credited to the member. The incremental cost of eligibility under this subsection shall be purchased by the employer at the full actuarial cost of the additional creditable service as determined by the retirement board acting on the advice of the actuary.

(e) At any time before a member's actual retirement date, the member may purchase noncontributory creditable service equal in amount to the period the member:

(1) was on verifiable workers' compensation leave due to an injury sustained in the course and scope of employment by an employer;

(2) was on an authorized leave of absence from an employer; or

(3) performed service for an employer in a position the service for which is not otherwise creditable in the retirement system.

(e-1) An active contributory member that is eligible for retirement may file a written application to convert to creditable service at retirement all or part of the member's sick leave accrued with the employer that is eligible for conversion. The application must be approved by the retirement board. The member may not convert sick leave for which the member is entitled to be paid by the employer. Sick leave hours may be converted in pay period increments for the purpose of increasing creditable service that is used in the calculation of benefits. Sick leave hours may not be used to reach retirement eligibility. Both the employer and the member must make the equivalent amount of retirement contributions that would have been made had the sick hours been exercised and used as sick leave hours.

(e-2) Nonqualified permissive creditable service may be purchased only as provided by this subsection. A member may purchase nonqualified permissive creditable service:

(1) only to the extent permitted under both this subsection and Section 415(n) of the code;

(2) in an amount that:

(A) for each purchase, is not less than one month; and

(B) when all amounts purchased under this subsection are combined, is not more than 60 months; and

(3) only if the member has reinstated all prior membership service in:

(A) Groups A and B if the member was initially enrolled as a member of Group A, but ceased to be a member of Group A, by:

(i) first reinstating all prior membership service in Group A;

(ii) next reinstating all prior membership service in Group B; and

(iii) then purchasing the nonqualified permissive creditable service; or

(B) Group B, if the member was initially enrolled as a member of Group B, by:

(i) first reinstating all prior membership service in Group B; and

(ii) then purchasing the nonqualified permissive creditable service.

(e-3) Nonqualified permissive creditable service purchased by members of Group B is not included in the creditable service required to qualify a member for normal or early retirement eligibility.

(f) The full actuarial cost of noncontributory creditable service purchased as provided by Subsections (e), (e-1), (e-2), and (e-3) of this section is payable by the member purchasing the credit.

(g) In this section, "noncontributory creditable service" means creditable service for which an employer contribution is not made.