(50 ILCS 45/30)
    Sec. 30. Statute of limitations. Units of local government have an obligation to review tax returns in a timely manner and issue any determination of tax due as promptly as possible so that taxpayers may make timely corrections of future returns and minimize any interest charges applied to tax underpayments. Each unit of local government must provide appropriate statutes of limitation for the determination and assessment of taxes covered by this Act, provided, however, that a statute of limitations may not exceed the following:
        (1) No notice of determination of tax due or
    
assessment may be issued more than 4 years after the end of the calendar year for which the return for the period was filed or the end of the calendar year in which the return for the period was due, whichever occurs later.
        (2) If any tax return was not filed or if during
    
any 4-year period for which a notice of tax determination or assessment may be issued by the unit of local government the tax paid or remitted was less than 75% of the tax due for that period, the statute of limitations shall be no more than 6 years after the end of the calendar year in which the return for the period was due or the end of the calendar year in which the return for the period was filed, whichever occurs later. In the event that a unit of local government fails to provide a statute of limitations, the maximum statutory period provided in this Section applies.
    This Section does not place any limitation on a unit of local government if a fraudulent tax return is filed.
(Source: P.A. 91-920, eff. 1-1-01.)