(35 ILCS 5/506) (from Ch. 120, par. 5-506)
    Sec. 506. Federal Returns.
    (a) In general. Any person required to make a return for a taxable year under this Act may, at any time that a deficiency could be assessed or a refund claimed under this Act in respect of any item reported or properly reportable on such return or any amendment thereof, be required to furnish to the Department a true and correct copy of any return which may pertain to such item and which was filed by such person under the provisions of the Internal Revenue Code.
    (b) Changes affecting federal income tax. A person shall notify the Department if:
        (1) the taxable income, any item of income or
deduction, the income tax liability, or any tax credit reported in an original or amended federal income tax return of that person for any year or as determined by the Internal Revenue Service or the courts is altered by amendment of such return or as a result of any other recomputation or redetermination of federal taxable income or loss, and such alteration reflects a change or settlement with respect to any item or items, affecting the computation of such person's net income, net loss, or of any credit provided by Article 2 of this Act for any year under this Act, or in the number of personal exemptions allowable to such person under Section 151 of the Internal Revenue Code, or
        (2) the amount of tax required to be withheld by that
person from compensation paid to employees and required to be reported by that person on a federal return is altered by amendment of the return or by any other recomputation or redetermination that is agreed to or finally determined on or after January 1, 2003, and the alteration affects the amount of compensation subject to withholding by that person under Section 701 of this Act.
Such notification shall be in the form of an amended return or such other form as the Department may by regulations prescribe, shall contain the person's name and address and such other information as the Department may by regulations prescribe, shall be signed by such person or his duly authorized representative, and shall be filed not later than 120 days after such alteration has been agreed to or finally determined for federal income tax purposes or any federal income tax deficiency or refund, tentative carryback adjustment, abatement or credit resulting therefrom has been assessed or paid, whichever shall first occur.
(Source: P.A. 97-507, eff. 8-23-11.)