205 ILCS 675/6

In addition to or in lieu of interest at a periodic rate or rates as provided in Section 5, and without limitation of the foregoing Section 4, a financial institution may, if the agreement governing the revolving credit plan so provides, charge and collect as interest, in such manner or form as the plan may provide, an annual or other periodic fee for the privileges made available to the borrower under the plan, a transaction charge or charges, late fees or delinquency charges, returned payment charges, over limit charges and fees for services rendered.