40 ILCS 5/20-123
The provisions governing a retirement annuity shall be applicable to a survivor's annuity. Appropriate credits shall be established for survivor's annuity purposes in those participating systems which provide survivor's annuities, according to the same conditions and subject to the same limitations and restrictions herein prescribed for a retirement annuity. If a participating system has no survivor's annuity benefit, or if the survivor's annuity benefit under that system is waived, pension credit established in that system shall not be considered in determining eligibility for or the amount of the survivor's annuity which may be payable by any other participating system.
For persons who participate in the self-managed plan established under Section 15-158.2 or the portable benefit package established under Section 15-136.4, pension credit established under Article 15 may be considered in determining eligibility for or the amount of the survivor's annuity that is payable by any other participating system, but pension credit established in any other system shall not result in any right to a survivor's annuity under the Article 15 system.
40 ILCS 5/20-123