Key Tax Filing Deadlines You Shouldn't Miss
Educational guide — every major filing date in one place, organized by filer type
Tax deadlines aren't one-size-fits-all — individuals, businesses, and trusts/estates all run on different clocks, with different extension rules. Here's the complete picture.
Individual Returns (Form 1040)
| Deadline | What's Due |
|---|---|
| April 15 | Form 1040 due for calendar-year filers |
| April 15 | Q1 estimated tax payment |
| June 15 | Q2 estimated tax payment |
| September 15 | Q3 estimated tax payment |
| October 15 | Extended Form 1040 due (if Form 4868 filed by April 15) |
| January 15 (following year) | Q4 estimated tax payment |
Dates shift to the next business day when they fall on a weekend or federal holiday.
The rule everyone needs to know: an extension buys time to file, not time to pay. Whatever you owe is still due April 15 regardless of an extension; interest and the failure-to-pay penalty start accruing from that date either way.
Business Returns
| Entity Type | Original Deadline | Extended Deadline |
|---|---|---|
| S-corporations (Form 1120-S) | March 15 | September 15 |
| Partnerships (Form 1065, incl. multi-member LLCs) | March 15 | September 15 |
| C-corporations (Form 1120) | April 15 | October 15 |
| Sole proprietors / single-member LLCs (Schedule C with Form 1040) | April 15 | October 15 |
The earlier March date for S-corps and partnerships exists so owners receive their Schedule K-1 in time to complete their own personal returns by April 15. Both use Form 7004 to request the extension.
C-corp estimated taxes run on a different schedule than individuals: April 15, June 15, September 15, and December 15 — note the fourth C-corp installment is in December, not the following January like individuals.
Trusts and Estates (Form 1041)
This is one of the most commonly mishandled deadlines, because the extension length is different from every other entity type.
| Calendar-Year Deadline | |
|---|---|
| Original filing deadline | April 15 |
| Extension length | 5.5 months (not 6 months) |
| Extended deadline | September 30 |
Fiduciaries used to individual or business return timelines often assume they get until mid-October, like a C-corp or an individual — they don't. Form 7004 for a trust or estate grants only 5.5 months, landing on September 30, with no further extension available beyond that. Missing this distinction is a common, avoidable error.
For a non-calendar fiscal year, the original deadline is the 15th day of the 4th month after the entity's tax year ends (for example, a trust with a June 30 year-end files by October 15), with the 5.5-month extension calculated from that date.
Trusts and estates are also subject to their own quarterly estimated tax rules, generally following the same April/June/September/January schedule as individuals — though an estate can skip the final quarterly installment if it files its completed Form 1041 and pays the full balance by January 31 of the following year.
Other Important Dates
| Deadline | What's Due |
|---|---|
| January 31 | Form W-2 to employees; Form 1099-NEC to contractors |
| April 15 | Prior-year IRA and HSA contribution deadline (even if you extend your return) |
| March 2 | Special deadline for farmers/fishers who skipped quarterly estimated payments — file and pay in full by this date to avoid the underpayment penalty |
Special Situations That Extend the Deadline
Living abroad: If your tax home and residence are both outside the U.S. on April 15, you get an automatic 2-month extension to June 15 — no form required, just attach a statement to your return explaining you qualify. Note that interest on any unpaid tax still runs from April 15 regardless. If you need more time beyond June 15, you can still file Form 4868 by June 15 to get the full extension to October 15.
Military service in a combat zone: Deployed service members generally get an extension of at least 180 days after leaving the combat zone, covering most filing and payment deadlines — plus any days that were left on the original deadline when they entered the combat zone.
Federally declared disaster areas: The IRS periodically announces extended deadlines for taxpayers in specific disaster-declared areas — these are announced case-by-case and can extend multiple deadlines (filing, payment, estimated taxes) by weeks or months, depending on the disaster.
The One Habit That Prevents Most Penalties
File something by the deadline — even just an extension — every time, whether or not you can pay in full. The failure-to-file penalty (5% of unpaid tax per month, up to 25%) is ten times steeper than the failure-to-pay penalty (0.5% per month). If you can't pay everything you owe, filing on time (or extending on time) and paying what you can is a far better outcome than filing late.
This article is for general educational purposes only and does not constitute tax, legal, or financial advice. Exact dates shift slightly year to year due to weekends, holidays, and disaster-relief announcements — always confirm the current year's deadlines at irs.gov or IRS Publication 509. Consult a qualified tax professional or CPA about deadlines specific to your situation.
Tax Code References
- IRC §6072 — Sets statutory due dates for filing income tax returns for individuals, corporations, and other entities.
- IRC §6081 and 26 CFR §1.6081-6 — Authorize extensions of time to file; specifically set the 5.5-month (not 6-month) automatic extension for Form 1041 trust and estate returns.
- IRC §6651 — Failure-to-file and failure-to-pay penalties.
- IRC §6654 — Underpayment of estimated tax penalty for individuals, trusts, and estates; includes the special rule for farmers and fishers.
- IRC §7508 — Extends deadlines for members of the Armed Forces serving in a combat zone or contingency operation.
- Form 4868, Form 7004 — Extension request forms for individual and business/trust/estate returns, respectively.
- Form 1041, Form 1041-ES — Income tax return and estimated tax voucher for estates and trusts.
- IRS Publication 509, Tax Calendars — The IRS's own comprehensive annual list of filing and deposit deadlines.
- IRS Publication 54 — Tax guide for U.S. citizens and resident aliens abroad, covering the automatic 2-month extension.
Deadlines shift annually based on weekends, holidays, and occasional disaster-relief extensions. Always verify the current year's exact dates before filing.