Tax Filing Deadline 2026: Every Date You Need to Know

When are taxes due 2026? 

Taxes were due April 15, 2026 for most individual and C-corporation returns covering the 2025 tax year. Partnerships and S-corporations had an earlier deadline of March 16, 2026. If you filed an extension, your new filing deadline is October 15, 2026 — but any tax owed still needed to be paid by April 15 to avoid interest and penalties. This is the answer whether you’re asking “when are taxes due,” “when are taxes due 2026,” or “deadline for taxes 2026” — they’re all the same question.

When is Tax Day? 

Tax Day is the annual federal deadline to file individual income tax returns and pay any tax owed. It’s set at April 15 each year, unless that date falls on a weekend or federal holiday, in which case it moves to the next business day. For 2026, Tax Day fell on Wednesday, April 15, 2026.

When is the last day to file taxes? 

For individuals who didn’t request an extension, the last day to file taxes was April 15, 2026. For anyone who filed Form 4868, the last day to file — the tax extension deadline 2026 — is October 15, 2026. Businesses taxed as partnerships or S-corporations had an earlier last-day-to-file of March 16, 2026, with an extended deadline of September 15, 2026.

When can I file my taxes for 2025? 

The IRS opened the 2026 filing season and began accepting 2025 tax year returns on January 26, 2026. IRS Free File opened even earlier, on January 9, 2026, for qualifying taxpayers. You can file any time between the IRS opening date and April 15.

When is tax season? 

Tax season runs from late January, when the IRS opens e-filing, through April 15, the filing deadline. For 2026, that window was January 26 – April 15. A second, quieter “tax season” runs through October 15 for anyone on extension.

Tax extension deadline 2026 

If you filed Form 4868 (individuals) or Form 7004 (businesses) by the original April 15 or March 16 deadline, here’s where your extended deadline landed:

• Individuals & C-corporations: extended to October 15, 2026
• Partnerships & S-corporations: extended to September 15, 2026

An extension moves your filing deadline, not your payment deadline. At least 90% of what you owed needed to be paid by the original due date to avoid a failure-to-pay penalty — this is the detail people searching “tax extension deadline 2025” or “2026” most often miss. You can request an individual extension using IRS Form 4868.

Full 2026 tax deadline calendar 

Business tax deadlines 

Business filing dates depend on entity type and fiscal year:

• Partnerships & S-corporations (calendar year): Form 1065 or 1120-S due March 16, 2026; extended deadline September 15, 2026.
• C-corporations (calendar year): Form 1120 due April 15, 2026; extended deadline October 15, 2026.
• Fiscal-year businesses: returns are generally due the 15th day of the third month (pass-through) or fourth month (C-corp) after your fiscal year ends — not tied to the calendar-year dates above.
• Payroll reporting: W-2s and 1099-NECs were due to employees and contractors by February 2, 2026 (moved from the usual January 31, which fell on a weekend).

This is where a lot of the general “income tax compliance deadlines 2026” confusion comes from — businesses are juggling payroll, pass-through, and entity-level deadlines that all land on different dates, plus quarterly obligations layered on top.

Quarterly estimated tax payments

Self-employed professionals, freelancers, investors, and business owners without withholding pay estimated tax four times a year:

• April 15, 2026 — Q1
• June 15, 2026 — Q2
• September 15, 2026 — Q3
• January 15, 2027 — Q4

Paying 90% of your current-year liability or 100–110% of last year’s (depending on income) generally avoids an underpayment penalty even if your estimate isn’t exact.

What happens if you miss a deadline? 

This depends on whether you owe money or are due a refund.

If you’re owed a refund: There’s typically no penalty for filing late. You generally have three years from the original due date to claim it — for a 2025 return due April 2026, that window closes in 2029. After that, an unclaimed refund becomes the property of the U.S. Treasury.

If you owe taxes: The IRS begins charging a failure-to-file penalty (up to 5% of unpaid tax per month, capped at 25%) plus a separate failure-to-pay penalty and interest starting the day after the deadline. Filing immediately — even without full payment — stops the larger failure-to-file penalty from continuing to accrue.

If you missed a quarterly estimated payment: Pay it as soon as possible. The penalty scales with how much you owe and how late you are, so speed matters more than precision.

If you can’t pay what you owe: File on time regardless, pay what you can, and set up an IRS payment plan for the rest. Not filing because you can’t pay in full is the costliest mistake — it triggers the larger of the two penalties for no benefit.

Disaster-area extensions: If you’re in a federally declared disaster area, the IRS often automatically postpones both filing and payment deadlines. Check IRS.gov for current disaster relief declarations if this applies to you.

How KMK Ventures keeps you ahead of every deadline

Missing deadlines is rarely about not knowing the date — it’s about records not being ready in time: late payroll data, incomplete books, or not enough internal bandwidth during the January–April crunch. KMK Ventures provides:

• Accounting and bookkeeping support
• Tax preparation assistance
• Payroll processing support
• Financial reporting
• Scalable finance teams that flex up during tax season without a permanent headcount increase

Read next: S Corp Tax Return Deadline 2026: Key Dates, Filing Checklist, and Penalties