Indiana Income Tax Filing Deadlines by Tax Year The majority of deadlines listed here are for the 2024 tax year. Some apply to upcoming tax years and some are IRS or federal deadlines. Note that the April 15 and October 15 filing deadlines vary by year but are generally on or around the 15th of these months. The links pages will have the latest updates. IN Tax Deadlines Deadline Type Description Tax Day, April 15 IRS and State Income Tax Return Prepare and e-file IRS your Indiana income tax returns by this timely date - eFileIT. Tax Day, April 15 Income Tax Extension See Indiana Income tax extension details. October 15 Individual Income Tax Return After the April Tax Day deadline This is the last day to e-file an Indiana state income tax return for extension filers and late filers. You can only e-file your Indiana return together with your IRS return - eFileIT. To file by paper, see below. Oct. 15 via Nail-In Forms. Individual Income Tax Return after the Deadline This is the deadline for taxpayers who got an IN tax extension to file their Indiana return by mail. See instructions on how to only - without the IRS return - prepare and file an Indiana tax return on eFile.com. As Soon as Possible Tax Amendment for all Tax Years See detailed instructions on how to prepare and mail in an Indiana State Income Tax Return Amendment. IRS Due Dates IRS Tax Return, Extension, Amendment Deadlines See detailed current and future federal or IRS income tax deadlines. All Deadlines and Years Other State Tax Return, Extension, Amendment Deadlines Select respective state tax return deadlines. All Deadlines and Years IRS Federal Income Tax Return, Amendment, Extension Deadlines See current year income tax return deadlines. April 15, Three Years Later Indiana Income Tax Return RefundIRS Tax Return Refund Claim Deadline This is the last day to file - you will not face late filing penalties - and claim your Indiana tax refund. This deadline does not apply if you owe income taxes. TurboTax® is a registered trademark of Intuit, Inc. H&R Block® is a registered trademark of HRB Innovations, Inc.