40 ILCS 5/16-151
Upon termination of employment as a teacher for any cause other than death or retirement, a member shall be paid the following amount upon demand made at least 4 months after ceasing to teach:
Any such amounts may be paid to the member either in one sum or, at the election of the board, in 4 quarterly payments.
Contributions credited to a member for periods of disability as provided in Sections 16-149 and 16-149.1 are not refundable.
Upon acceptance of a refund, all accrued rights and credits in the System are forfeited and may be reinstated only if the refund is repaid together with interest from the date of the refund to the date of repayment at the following rates compounded annually: for periods prior to July 1, 1965, regular interest; for periods from July 1, 1965 to June 30, 1977, 4% per year; for periods on and after July 1, 1977, regular interest. Repayment shall be permitted upon return to membership; however, service credit previously forfeited by a refund and subsequently reinstated may not be used as a basis for the payment of benefits, other than a refund of contributions, prior to the completion of one year of creditable service following the refund, except when repayment is permitted under the provisions of the "Retirement Systems Reciprocal Act" contained in Article 20.
40 ILCS 5/16-151