When are taxes due? Federal and Illinois dates for 2025 and 2026 returns
Federal and Illinois due dates for 2025 and 2026 returns, estimated tax and common forms. The 2027 dates are our own math until IRS publishes its calendar.
Prepared by Prem Tax and Accounting Corp. Last checked against official sources on October 24, 2026.
Individual returns for tax year 2025 were due April 15, 2026, and extended returns October 15, 2026, which has now passed. For tax year 2026 the dates are Thursday, April 15, 2027, and Friday, October 15, 2027, with an extension. A due date on a weekend or legal holiday moves to the next business day.
- Tax year 2025: April 15, 2026, or October 15, 2026 with an extension (passed).
- Tax year 2026: Thursday, April 15, 2027, or Friday, October 15, 2027 with an extension.
- An extension gives more time to file, not to pay. Tax owed is still due in April.
- As of October 2026 the IRS has not published its 2027 calendar, so the 2027 dates here are our own calendar math from the standing rules.
- Illinois follows the same April date and gives an automatic six months to file. Any tax owed is still due in April.
Dates to put on your calendar
| Date | What is due |
|---|---|
| Jan 15, 2027 | Fourth estimated payment for 2026. You can skip it by filing and paying in full by Feb 1, 2027. |
| Feb 1, 2027 | W-2s due to the Social Security Administration (Jan 31 is a Sunday). |
| Mar 15, 2027 | Partnership (Form 1065) and S corporation (Form 1120-S) returns. |
| Apr 15, 2027 | Individual returns and payments for 2026, Form 4868, the first 2027 estimated payment, and C corporation returns (Form 1120). |
| Jun 15 and Sep 15, 2027 | Second and third 2027 estimated payments. Sep 15 is also the extended date for partnerships and S corporations. |
| Oct 15, 2027 | Extended individual and C corporation returns. |
Check these against the tax calendar and the IRS calendar once it is published.
Dates that can change yours
- Disaster areas. The IRS lists postponements by event. As of October 14, 2026, many 2026 events show February 1, 2027. Check your county.
- Living or serving abroad. Taxpayers who live, or are on military duty, outside the U.S. and Puerto Rico get an automatic two extra months, to June 15, to file and pay. Interest still runs from April, and you attach a statement.
- Mailing. Since December 24, 2025, a postmark can show the first automated-processing date, one to three days after drop-off. E-file, or get a postmark at the counter.
What to do next
- Mark the dates that apply to you, including estimated payments if you are self-employed or have other untaxed income.
- If you cannot file on time, request an extension and pay what you can by the original date.
- Bring last year's return and a list of the estimated payments you have made.
Common questions
When are estimated taxes due?
For 2026 they were due April 15, June 15 and September 15, 2026, and the last is January 15, 2027. Illinois uses the same dates and has its own $1,000 trigger for needing to pay.
I was on extension for 2025. Is it too late?
The extended deadline passed on October 15, 2026. File as soon as you can. The late-filing penalty builds month by month, so each month counts. File even if you cannot pay in full.
When do W-2 and 1099 forms arrive?
Employers send W-2s by January 31. In 2027 that falls on a Sunday, so the date moves to February 1. Statements for Forms 1099-B, 1099-DA and 1099-S are due to recipients in mid-February, February 16 in 2027 by our calendar math.
What about business returns?
Partnerships and S corporations file by March 15 (March 16 in 2026) and C corporations by April 15. Form 7004 extends them by six months.
Official sources
- IRS: Publication 509, tax calendars
- IRS: Tax relief in disaster situations
- IRS: Tax Topic 304, extensions of time to file
- Taxpayer Advocate Service: New U.S. Postal Service rules and your filing deadline
- Illinois Department of Revenue: Due dates and extensions
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