Does Indiana Accept the Federal Tax Extension?

Yes. Indiana does accept the federal tax extension, and it does so automatically: if you have a valid IRS Form 4868 in place, your Indiana return gets an extra month beyond the federal extended due date without any separate state paperwork.¹ The important catch: the extension only buys you time to file. Indiana still expects at least 90% of your state and county tax by the original April 15 deadline, and interest runs on any unpaid balance from that date at 7% for 2026.²

What the Federal Extension Gets You in Indiana

The federal extension runs six months, pushing most individual filers from April 15 to October 15. Indiana adds one more month on top of that, so your Form IT-40 or IT-40PNR is due November 15.¹ You do not file Indiana Form IT-9. You do not call the Department of Revenue. You do not request anything.

When you eventually file your Indiana return, enclose a copy of your federal Form 4868 with it. That is the full extent of the state-level process.³

You Still Have to Pay by April 15

This is where most people get burned. A federal extension is not an extension of time to pay, and Indiana follows the same rule for state and county income tax.¹ To stay clear of the late-payment penalty, three things need to happen:

At least 90% of your total state and county tax liability is paid by April 15.
Your return is filed by November 15 (for most calendar-year filers).
The remaining balance, plus interest, is paid when you file.

If the balance owed on your return turns out to be more than 10% of your total state and county tax, the Department of Revenue will assess a penalty of 10% of the unpaid amount, or $5, whichever is greater, even with a valid extension on file.¹⁴

Indiana’s individual income tax rate for 2026 is 2.95%, plus your county rate, so estimating what you owe does not require much math.⁴

How to Send the Payment

Two options get your money to the state by April 15:

Pay online through INTIME, the Indiana Taxpayer Information Management Engine portal. This is the fastest route and gives you an immediate confirmation.
Mail a check with Form IT-9. When you already have a federal extension, IT-9 functions purely as a payment voucher; you are not requesting a state extension with it.

Interest Runs Even If You Hit 90%

Interest accrues on any unpaid balance starting April 15 at 7% annually for 2026, whether or not you avoided the penalty.² On a $1,000 unpaid balance, that works out to roughly $5.83 per month until you pay it off. Interest cannot be waived.

What Happens If You Fall Short

Two separate penalties are in play, and a valid extension only shuts off one of them.

The failure-to-file penalty is 10% of the full tax due if you file late without an extension.⁵ If your return shows no tax liability, it is $10 per day late, capped at $250.⁶ A valid federal extension prevents this one entirely, as long as you file by November 15.

The failure-to-pay penalty is the one the extension does not touch. If less than 90% of your tax is paid by April 15, you owe 10% of the unpaid amount or $5, whichever is greater.⁴ No extension can waive it. The only defense is paying enough on time.

Current-Year Estimated Payments Are Not Extended

An extension for your prior-year return does nothing for your current-year estimated taxes. If you owe Indiana estimated tax for 2026, the first quarterly payment is still due April 15, 2026, regardless of your extension on the 2025 return. The remaining installments follow the usual schedule: June 15, September 15, and January 15, 2027. Mixing these two obligations up is an easy way to pick up an underpayment penalty on top of whatever else you owe.

Businesses Filing Form 7004

The same automatic recognition applies to business returns. When you file a federal Form 7004, Indiana extends the state deadline to one month after the federal extended due date for corporations (Form IT-20), S corporations (Form IT-20S), partnerships (Form IT-65), and financial institutions tax returns.⁷ No separate state request is needed.

Businesses that owe tax still have to pay by the original due date. The payment functions as a fifth-quarter estimated payment and can go through INTIME or on Form E-6.⁸ The 90% threshold is identical: fall below it on the original deadline and the late-payment penalty applies.⁷

Military and Disaster-Area Extensions

Active-duty military members stationed outside the United States and Puerto Rico on April 15 get an automatic 60-day extension on their Indiana return. A statement confirming the overseas location on that date goes with the return when filed.⁹

Service members in a combat zone get 180 days after leaving the zone, with the clock paused during any hospitalization outside the U.S. for combat zone service. Write “Combat Zone” across the top of the Indiana return before submitting it.⁹

For federally declared disasters, the Department of Revenue mirrors the IRS relief. Sometimes the extension is applied automatically; other times you need to call the DOR’s Taxpayer Advocate Office at 317-232-4692. Dates and affected tax types vary by declaration, so check the DOR’s disaster relief page if you have been impacted.¹⁰

1
Indiana Department of Revenue. Income Tax Information Bulletin 18
2
Indiana Department of Revenue. Departmental Notice 3 – Interest Rates for Calendar Year 2026
3
Indiana Department of Revenue. Extension of Time to File
4
Indiana Department of Revenue. Rates, Fees and Penalties
5
Indiana General Assembly. Indiana Code 6-8.1-10-2.1 – Liability for Penalty; Reasonable Cause Presumption
6
Indiana Department of Revenue. Fines, Fees and Penalties
7
Indiana Department of Revenue. Income Tax Information Bulletin 15
8
Indiana Department of Revenue. Form E-6 – Corporate Estimated Quarterly Income Tax Returns
9
Indiana Department of Revenue. Income Tax Information Bulletin 27 – Military Personnel
10
Indiana Department of Revenue. Disaster Relief