Ill. Admin. Code tit. 56 § 2915.20
The reasonable assurance referred to in Section 2915.10 shall be presumed if such individual has a written, verbal, or implied agreement that covers or extends into the second academic year or term, or after the vacation period or holiday recess, to perform for any educational institution or educational service agency, academic or non-academic services. Continuation of service in the second academic year or term or after the vacation period or holiday recess is implied if there has been a pattern of such continuation from one academic year or term to another or following vacation periods or holiday recesses over a number of years or when the individual has not been given a notice of termination by the educational institution or educational service agency providing employment in the first of the two academic years or terms or prior to the vacation period or holiday recess.
Ill. Admin. Code tit. 56, § 2915.20