305 ILCS 5/10-6
The administrative enforcement unit shall review the forms or questionnaires returned by each responsible relative and supplement the information provided therein, where required, by such additional consultations with the responsible relative and such other investigations as may be necessary, including genetic testing if paternity is an issue and, applying the standard or guidelines and regulations established by the Illinois Department, shall determine whether and the extent to which, the responsible relative individually or together in any combination, are reasonably able to provide support. If the child was born out of wedlock and the case is subject to the voluntary acknowledgment of paternity or the administrative determination of paternity under rules established under Section 10-17.7, the Child and Spouse Support Unit of the Illinois Department shall determine the child support obligation under subsection (b) of Section 10-7 upon establishing the child's paternity. If the child's paternity was established by judicial or administrative process in any other state, the Illinois Department may use administrative processes contained in this Article X to establish a child support order.
In aid of its investigative authority, the Child and Spouse Support Unit of the Illinois Department may use the subpoena power as set forth in this Article.
The Illinois Department, by rule, may authorize the administrative enforcement units to conduct periodic or other reinvestigations and redeterminations of the financial ability of responsible relatives. Any redeterminations shall have the effect of altering, amending, or modifying previous determinations and administrative orders entered pursuant to Sections 10-7 and 10-11. However, any redetermination which establishes liability for support or reimbursement, or which modifies the support or reimbursement liability specified in a prior order, shall be subject to the provisions of Section 10-12 and the administrative and judicial review procedures herein provided for original orders.
305 ILCS 5/10-6