Indiana individual income tax returns are due April 15, 2026, for income earned in 2025, and the first quarterly estimated payment is due the same day. Business returns, sales and withholding filings, and property tax bills each run on their own calendars, so the full answer to when Indiana taxes are due depends on which tax you owe.
Individual Income Tax: April 15
Full-year residents file Form IT-40. Part-year residents and nonresidents with Indiana income file Form IT-40PNR.1Indiana Department of Revenue. IT-40 Full Year Resident Individual Income Tax Booklet Either return is due April 15 for income earned in the prior calendar year.2Indiana General Assembly. Indiana Code 6-3-4-3 – Filing Date If April 15 falls on a weekend or legal holiday, the deadline shifts to the next business day.3Indiana Department of Revenue. Tax Filing Deadlines
Your return has to be postmarked or electronically submitted by that date. File late with a balance owed and the penalty is 10 percent of the unpaid tax or $5, whichever is greater.4Indiana Department of Revenue. Fines, Fees and Penalties Interest starts accruing immediately on any unpaid balance at 7 percent for 2026.5Indiana Department of Revenue. Interest Rates for Calendar Year 2026
Your county’s local income tax is calculated and paid on the same state return. There is no separate county filing or county deadline.6Indiana Department of Revenue. General Information on Local Income Taxes
Quarterly Estimated Payments
If you expect to owe $1,000 or more in combined state and county tax beyond what your employer withholds, you need to make estimated payments on Indiana’s quarterly schedule:7Indiana Department of Revenue. Estimated Payments
- April 15 (first installment, same day as the annual return)
- June 15 (second installment)
- September 15 (third installment)
- January 15 of the following year (fourth installment)
Pay through INTIME, Indiana’s online tax portal, or mail Form ES-40 with a check.
Miss or short-pay an installment and the penalty is 10 percent of the underpaid amount for that period, even if your annual return ultimately shows a refund. You stay clear of the penalty if your withholding plus estimated payments add up to at least 90 percent of the current year’s tax or 100 percent of last year’s tax. The prior-year figure rises to 110 percent if your federal adjusted gross income exceeded $150,000, or $75,000 if married filing separately.
Business Returns
Entity type determines the deadline, and the Indiana date does not always match the federal date.
C-Corporations
Form IT-20 is due the 15th day of the fifth month after the close of the tax year.8Indiana Department of Revenue. General Tax Information Bulletin 303 – Corporate Income Tax Return Due Dates After Change in Federal Due Dates For a calendar-year corporation, that is May 15. Late filing carries a 10 percent penalty on the tax due.
S-Corporations and Partnerships
Form IT-20S and Form IT-65 are due the 15th day of the fourth month after the tax year closes, which is April 15 for calendar-year entities.8Indiana Department of Revenue. General Tax Information Bulletin 303 – Corporate Income Tax Return Due Dates After Change in Federal Due Dates Shareholders and partners need the information from these returns to complete their own filings. The late-filing penalty is $10 per day past the due date, capped at $250.
Composite Returns for Nonresident Partners
Indiana partnerships file a composite adjusted gross income tax return covering their nonresident partners.9Indiana General Assembly. Indiana Code 6-3-4-12 – Nonresident Partners; Withholding Rate; Returns; Credits for Tax Withheld Where the department permits annual filing because the partnership pays or credits amounts only once per year, the composite return and payment are due the 15th day of the fourth month after year-end, the same date as the IT-65. Each nonresident partner also has to receive a record of the tax withheld by the 15th day of the third month after the tax year ends.
Sales and Withholding Tax
Businesses that collect sales tax or withhold employee income tax file on a monthly cycle, with the specific due date pegged to average liability:
- Average monthly liability of $1,000 or more: returns due by the 20th of the following month
- Average monthly liability under $1,000: returns due by the 30th of the following month
Both sales tax returns (Form ST-103) and withholding tax returns (Form WH-1) follow these dates.3Indiana Department of Revenue. Tax Filing Deadlines A weekend or holiday due date pushes to the next business day. Employers also file an annual withholding reconciliation on Form WH-1 by January 31 covering the prior calendar year. Late payment of either tax carries a 10 percent penalty.
Property Tax: May 10 and November 10
Indiana property tax is paid in two installments. For 2026, the deadlines are May 10, 2026, and November 10, 2026.10IN.gov. Property Tax Due Dates Payment goes to your county treasurer, not the Indiana Department of Revenue.
Pay within 30 days of the due date with no back taxes on the same property and the late penalty is 5 percent of the unpaid amount. After 30 days, or if you have back taxes, the penalty climbs to 10 percent.
Filing an Extension
You can request an extension if you cannot file by April 15, but the request itself has to be in before the original deadline. An extension buys time to file, not time to pay.11Indiana General Assembly. Indiana Code 6-8.1-6-1 – Due Date Extensions; Requirements; Tax
To stay penalty-free, pay at least 90 percent of what you expect to owe by April 15.12Indiana Department of Revenue. Extension of Time to File The rest, plus any interest, is due by November 16, 2026, for the 2025 tax year. Miss the extended deadline, or fall short of the 90 percent prepayment, and the extension is treated as void. Late-filing penalties then apply retroactively from the original April date.
Amending a Prior Return
Found an error on a return you already filed? You can file an amended return to claim a refund within three years of the original due date or the date you paid the tax, whichever is later.13Indiana Department of Revenue. Amend A Return
The Department of Revenue has the same three years from the filing date to assess additional tax. Filing an amended return resets that three-year clock from the date you file the amendment. Underreport income by 25 percent or more and the state gets six years instead of three to assess additional tax.14Cornell Law School. 45 IAC 15-5-7 – Statute of Limitations on Issuance of Proposed Assessment
Penalties and Interest Summary
- Late payment of individual income tax: 10 percent of unpaid tax or $5, whichever is greater
- Underpayment of estimated tax: 10 percent of the underpaid amount per installment period
- Late filing of corporate income tax (IT-20): 10 percent of tax due
- Late filing of S-corporation (IT-20S) or partnership (IT-65) returns: $10 per day past the due date, up to $250
- Late payment of sales or withholding tax: 10 percent of tax due
- Late property tax within 30 days with no back taxes: 5 percent of the unpaid amount
- Late property tax after 30 days or with back taxes: 10 percent of the unpaid amount
Interest runs on unpaid balances at 7 percent for calendar year 2026.5Indiana Department of Revenue. Interest Rates for Calendar Year 2026 The rate is reset each year based on the average investment yield on state general fund money. Penalties and interest are charged separately and stack, so delaying payment costs more than filing an extension and paying what you can by April 15.