44 Ill. Adm. Code 6.660
Computation of Time
Section 6.660 Computation of Time
a) Computation
of any period of time prescribed by this Subpart I begins with the first
business day following the day on which the act, event or development
initiating such period of time occurs, and runs until the end of the last day,
or the next following business day if the last day is a Saturday, Sunday, or
legal holiday. When the period of time is five days or less, Saturdays,
Sundays and legal holidays are excluded in the computation of time.
b) Notice
requirements shall be construed to mean notice received, but proof that notice
was dispatched by means reasonably calculated to be received by the prescribed
date shall be prima facie proof that the notice was timely received.