(a) When an administrative enforcement unit has determined that a responsible relative is financially able to contribute to the support of an applicant or recipient, the responsible relative shall be notified by mailing him a copy of the determination by United States registered or certified mail, advising him of his legal obligation to make support payments for such period or periods of time, definite in duration or indefinite, as the circumstances require. The notice shall direct payment as provided in Section 10-8. Where applicable, the determination and notice may include a demand for reimbursement for emergency aid granted an applicant or recipient during the period between the application and determination of the relative’s obligation for support and for aid granted during any subsequent period the responsible relative was financially able to provide support but failed or refused to do so.
     (b) In the alternative, when support is sought on behalf of applicants for or recipients of financial aid under Article IV of this Act and other persons who are given access to the child support enforcement services of this Article as provided in Section 10-1, the administrative enforcement unit shall not be required to send the notice and may enter an administrative order immediately under the provisions of Section 10-11. The order shall be based upon the determination made under the provisions of Section 10-6 or, in instances of default, upon the needs of the persons for whom support is sought. In addition to requiring payment of future support, the administrative order may require payment of support for a period before the date the order is entered. The amount of support to be paid for the prior period shall be determined under the guidelines established by the Illinois Department pursuant to Section 10-3. The order shall direct payment as provided in Section 10-10.