The taxpayer shall file the notice on the form prescribed by the department within one hundred twenty (120) days after the modification is made if the modification was made before January 1, 2011, and one hundred eighty (180) days after the modification is made if the modification is made after December 31, 2010.
for a taxable year, regardless of whether a modification results in an underpayment or overpayment of tax. In the case of a taxpayer that files a consolidated return under section 14 of this chapter or either files or is required to be included by the department in a combined return under IC 6-3-2-2, 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 consolidated or combined return.
IC 6-3-4-6