From IPERS Monthly Update, July 1, 1992
Temporary employees are excluded from IPERS coverage provided they have not established an ongoing relationship with an IPERS' covered employer. They establish that relationship when the employee is paid wages of $300 or more in two consecutive quarters, or if the employee is employed by a covered employer for 1,040 or more hours in a calendar year. Coverage will begin the quarter after the permanency of the relationship is established.
Employees who come back to employment with the same employer within one year (within four full quarters) of their previous employment are treated as already qualified for IPERS' coverage (provided they had met the $300 or more in two consecutive quarters originally).
However, if these employees return to the same employer after remaining out of employment for more than four full quarters, the employer would treat the employees as temporary employees who would again need to qualify for coverage, that is, they met the $300 or more in two consecutive quarters before being covered the next quarter.
Bottom line: if last summer's seasonal employees earned $300 in two consecutive quarters and are now returning before four full quarters have elapsed, they would be covered under IPERS from the first day of employment, whether or not they were covered under IPERS last summer.