40 ILCS 5/9-162
An employee other than a present employee described in subdivision (c) of Section 9-109 who was not in the service of such county or of the board on the day prior to the effective date, and who was in service prior to that date and who re-enters the service after that date and before age 65, shall not be credited for prior service annuity or widow's prior service annuity on account of service prior to the effective date. The period of service, prior to the effective date, shall, however, be included in computing service for age and service annuity, widow's annuity and ordinary disability purposes.
Contributions by the employee and county contributions for age and service annuity and widow's annuity shall be made until such employee attains age 65.
Any such employee shall have a right to receive age and service annuity, from the date of withdrawal from service, as of his age on such date, provided from the total sum accumulated to his credit for such purposes on such date.
The amount of annuity for the wife or widow of any such employee, from the date of the death of such employee, shall be fixed in accordance with the provisions of this Article relating to annuities for widows of future entrants.
The foregoing provisions of this section shall apply to any employee who was not in service of such county or of the board on the day prior to the effective date, unless such employee qualifies as a present employee as described in subdivision (c) of Section 9-109, in which event he shall be credited for prior service annuity and widow's prior service annuity with accumulated sums computed as prescribed in this Article. The period of service rendered by such employee prior to the day before the effective date shall be credited in addition to the periods of service otherwise credited to such employee.
40 ILCS 5/9-162