Section 750 ILCS 5/511 - ProcedureA judgment of dissolution or of legal separation or of declaration of invalidity of marriage may be enforced or modified by order of court pursuant to petition.
(a) Any judgment entered within this State may be enforced or modified in the judicial circuit wherein such judgment was entered or last modified by the filing of a petition with notice mailed to the respondent at his last known address, or by the issuance of summons to the respondent. If neither party continues to reside in the county wherein such judgment was entered or last modified, the court on the motion of either party or on its own motion may transfer a post-judgment proceeding, including a proceeding under the Income Withholding for Support Act, to another county or judicial circuit, as appropriate, where either party resides. If the post-judgment proceeding is with respect to maintenance or support, any such transfer shall be to the county or judicial circuit wherein the recipient or proposed recipient of such maintenance or support resides.(b) In any post-judgment proceeding to enforce or modify in one judicial circuit the judgment of another judicial circuit of this State, the moving party shall commence the proceeding by filing a petition establishing the judgment and attaching a copy of the judgment as a part of the petition. The parties shall continue to be designated as in the original proceeding. Notice of the filing of the petition shall be mailed to the clerk of the court wherein the judgment was entered and last modified in the same manner as notice is mailed when registering a foreign judgment. Summons shall be served as provided by law.(c) In any post-judgment proceeding to enforce or modify the judgment of another state, the moving party shall commence the proceeding by filing a petition to enroll that judgment, attaching a copy thereof as a part of the petition and proceed as provided for in paragraph (b) hereof.(d) In any post-judgment proceeding to enforce a judgment or order for payment of maintenance or support, including a proceeding under the Income Withholding for Support Act, where the terms of such judgment or order provide that payments of such maintenance or support are to be made to the clerk of the court and where neither party continues to reside in the county wherein such judgment or order was entered or last modified, the court on the motion of either party or on its own motion may transfer the collection of the maintenance or support to the clerk of the court in another county or judicial circuit, as appropriate, wherein the recipient of the maintenance or support payments resides. P.A. 90-673, eff. 1/1/1999.