35 ILCS 5/505
2021 Illinois Compiled Statutes|Chapter 35 - REVENUE|35 ILCS 5/ - Illinois Income Tax Act.|Article 5 - Records, Returns And Notices

 (from Ch. 120, par. 5-505)Sec. 505.     Time and Place for Filing Returns.     (a) In general.  Returns required by this Act shall be filed at such place  as the Department may by regulations prescribe.(1) Corporations.  Except as provided in paragraph (3), corporate  returns shall be filed on or before the 15th day of the third month following  the close of the taxable year, unless, subject to the provisions of Section  602, the Director grants an extension or extensions of time (not to exceed  6 months in the aggregate) for such filing, or unless the income or loss  of a taxpayer is reported for federal purposes on a return with a due date later  than the 15th day of the third month following the close of the taxable  year, in which case the same due date shall apply to the corresponding Illinois return.(2) Individuals, partnerships and fiduciaries.  Except as provided in  paragraph (3), individual, partnership and fiduciary returns  shall be filed on or before the 15th day of the fourth month following the  close of the taxable year, unless, subject to the provisions of Section  602, the Director grants an extension or extensions of time (not to exceed  6 months in the aggregate) for such filing, except that a final  return of a decedent shall be filed at the time (including any extensions  thereof) it would have been due if the decedent had not died.(3) Certain Exempt Organizations.  Organizations which are exempt from  the Federal income tax by reason of Section 501(a) of the Internal Revenue  Code who determine base  income for a taxable year under subsection (a) of Section 205 (other than  an employees' trust described in Section 401(a) of the Internal Revenue  Code), shall file returns required by this Act on or before the 15th day  of the 5th month following the close of the taxable year, unless, subject  to the provisions of Section 602, the Director grants an extension or extensions  of time (not to exceed 6 months in the aggregate) for such filing.(b) Extension of time for filing federal return.  When the taxpayer has  been granted an extension or extensions of time within which to file his  federal income tax return for any taxable year, the filing of a copy of  such extension or extensions with the Department shall automatically extend  the due date of the return with respect to the tax imposed by this Act for  an equivalent period (plus  an additional month beyond the federal extension in the case of  corporations) if the requirements of Section 602 are met.(c) Extension of time for filing when abroad.  If an individual is  living or traveling outside the United States and Puerto Rico on the 15th  day of the 4th month following the close of his taxable year ending on or  after December 31, 1983, the return required  to be filed under Section 502 of this Act relative to that taxable year  shall, in no event, be due prior to the 15th day of the 6th month following  the close of that taxable year.  In the case of a joint return filed in  accordance with Section 502(c), the 2 month extension provided for in this  subsection (c) is available if either spouse is living or traveling outside  the United States and Puerto Rico on the 15th day of the 4th month following  the close of the taxable year ending on or after December 31, 1983.  Nothing  in this subsection (c) shall be construed to extend the time in which the  individual must pay the tax due under Section 601(a).    (Source: P.A. 84-1400.)