Sec. 6. (a) Each taxpayer shall notify the department in writing of any alteration or modification of a federal income tax return filed with the United States Internal Revenue Service for a taxable year that begins after December 31, 1988, including any modification or alteration in the amount of tax, regardless of whether the modification or assessment results from an assessment.
(b) The taxpayer shall file the notice in the form required by the department within one (1) year after the alteration or modification is made. In the case of a taxpayer that files a combined return under this article, the date on which the alteration or modification is made shall be considered to be the last day on which an alteration or modification occurs for any entity filing as part of the combined return.
(c) For purposes of this section, a modification or alteration occurs on the date on which a:
(1) taxpayer files an amended federal income tax return;
(2) final determination is made concerning an assessment of deficiency;
(3) final determination is made concerning a claim for refund;
(4) taxpayer waives the restrictions on assessment and collection of all, or any part, of an underpayment of federal income tax by signing a federal Form 870, or any other Form prescribed by the Internal Revenue Service for that purpose. For purposes of this subdivision:
(A) a final determination does not occur with respect to any part of the underpayment that is not covered by the waiver; and
(B) if the signature of an authorized representative of the Internal Revenue Service is required to execute a waiver, the date of the final determination is the date of signing by the authorized representative of the Internal Revenue Service or by the taxpayer, whichever is later;
(5) taxpayer enters into a closing agreement with the Internal Revenue Service concerning the taxpayer's tax liability under Section 7121 of the Internal Revenue Code that is a final determination. The date the taxpayer enters into a closing agreement under this subdivision is the date the closing agreement is signed by an authorized representative of the Internal Revenue Service or by the taxpayer, whichever is later; or
(6) modification or alteration in an amount of tax, adjusted gross income, taxable income, credit, or other tax attribute is otherwise made that is a final determination;
for a taxable year, regardless of whether a modification or alteration results in an underpayment or overpayment of tax.
(d) For purposes of subsection (c)(2) through (c)(6), a final determination means an action or decision by a taxpayer, the Internal Revenue Service (including the Appeals Division), the United States Tax Court, or any other United States federal court concerning any disputed tax issue that:
(1) is final and conclusive; and
(2) cannot be reopened or appealed by a taxpayer or the Internal Revenue Service as a matter of law.
(e) If the federal modification or alteration results in a change in the taxpayer's federal adjusted gross income or income within Indiana, the taxpayer shall file an amended Indiana financial institutions tax return (as required by the department) and a copy of the taxpayer's amended federal income tax return with the department not later than the date that is one hundred eighty (180) days after the modification or alteration is made, if the modification or alteration occurs before January 1, 2026, and one (1) year if the modification or alteration occurs after December 31, 2025.
(f) The taxpayer shall pay an additional tax or penalty due under this article upon notice or demand from the department.
As added by P.L.347-1989(ss), SEC.1. Amended by P.L.242-2015, SEC.32; P.L.159-2021, SEC.28; P.L.128-2026, SEC.24.
