Running a business means the IRS expects money from you throughout the year, not just at filing time. Estimated tax payments, payroll deposits, information returns, and entity-level tax filings each follow their own schedule, and the penalties for missing them range from annoying to devastating. This calendar covers every federal deadline a new business owner needs to know, organized by when it hits.
Missing business tax deadlines costs real money. Partnership and S-Corp late-filing penalties start at $255 per owner per month -- even if no tax is owed. Payroll deposit failures can trigger personal liability for 100% of unpaid trust fund taxes under IRC Section 6672.
January 15 -- Q4 estimated tax payment due. This covers income earned September 1 through December 31 of the prior year. If you file your annual return and pay the full balance by January 31, you can skip this payment. IRC Section 6654(h)(2).
January 31 -- W-2s to employees. Every employee who worked for you during the prior year must receive their Form W-2 by this date. You must also file copies with the Social Security Administration by the same deadline. There is no automatic extension for W-2s.
January 31 -- 1099-NEC to contractors. If you paid any non-employee $600 or more for services during the year, Form 1099-NEC must be in their hands by January 31. The IRS filing deadline is the same date -- no gap between the recipient copy and the IRS copy. There is no automatic extension for 1099-NEC filings either.
January 31 -- Form 940 due. Your annual Federal Unemployment Tax Act (FUTA) return for the prior year is due. Technical detail
January 31 -- Form 941 for Q4 due. Your quarterly payroll tax return for October through December is due. If you deposited all payroll taxes on time throughout the quarter, you get an extra 10 calendar days (until February 10).
February and March: Entity Returns and the S-Corp Election Window
February 28 -- 1099-MISC and other information returns (paper filing). If you file Form 1099-MISC or other information returns on paper, the IRS deadline is February 28. Electronic filers get until March 31. The recipient copies of most 1099 forms were already due January 31.
March 15 -- Form 1065 (partnerships). If your business is structured as a partnership or a multi-member LLC taxed as a partnership, your Form 1065 is due. Each partner must also receive their Schedule K-1 by this date.
March 15 -- Form 1120-S (S-corporations). Your S-Corp return is due on the same date. Schedule K-1 forms must go to shareholders by this deadline. IRC Section 6072(b). The March 15 deadline applies to calendar-year S-Corps and partnerships.
March 15 -- Form 2553 (S-Corp election). If you want your existing LLC or corporation to be taxed as an S-Corp for the current tax year, Form 2553 must be filed by this date. The technical rule is two months and 15 days after the start of the tax year. Miss it, and the election cannot take effect until the following year -- unless you qualify for late election relief under Revenue Procedure 2013-30.
March 31 -- 1099-MISC and other information returns (electronic filing). The e-filing deadline for most information returns other than 1099-NEC.
April: The Big One
April 15 -- Form 1040 with Schedule C (sole proprietors and single-member LLCs). If your business is a sole proprietorship or a single-member LLC (and you have not elected S-Corp or C-Corp treatment), your business income flows to Schedule C on your personal Form 1040. The filing deadline is April 15. IRC Section 6072(a).
April 15 -- Form 1120 (C-corporations). Calendar-year C-Corps file their Form 1120 by the 15th day of the fourth month after the tax year ends. For calendar-year filers, that is April 15. IRC Section 6072(b).
April 15 -- Q1 estimated tax payment due. Your first quarterly estimated payment for the current year, covering income earned January 1 through March 31. This applies to sole proprietors, partners, S-Corp shareholders, and anyone else with income not subject to adequate withholding.
April 30 -- Form 941 for Q1 due. Your quarterly payroll tax return for January through March.
June Through September: Mid-Year Deadlines
June 15 -- Q2 estimated tax payment due. Covers income earned April 1 through May 31. Despite covering only two months, the payment amount is typically one-quarter of your annual estimated obligation if you use the equal-installment method.
July 31 -- Form 941 for Q2 due. Quarterly payroll tax return for April through June.
September 15 -- Q3 estimated tax payment due. Covers income earned June 1 through August 31.
September 15 -- Extended partnership (Form 1065) and S-Corp (Form 1120-S) returns due. If you filed Form 7004 for a six-month extension back in March, the extended deadline is today.
October: Extension Deadlines
October 15 -- Extended Form 1040 due. If you filed Form 4868 for a personal extension, your return (including Schedule C) is due today. The extension gives you extra time to file, not extra time to pay -- interest and late-payment penalties have been running since April 15 on any unpaid balance.
October 15 -- Extended Form 1120 (C-Corp) due. C-Corps that filed Form 7004 for an automatic six-month extension must file by this date.
October 31 -- Form 941 for Q3 due. Quarterly payroll tax return for July through September.
Payroll tax deposits do not follow the quarterly Form 941 schedule. They are due far more frequently, and the schedule depends on your total payroll tax liability during a lookback period.
Monthly depositors. If your total payroll tax liability during the lookback period (July 1 through June 30 of the prior year) was $50,000 or less, you deposit monthly. Deposits are due by the 15th of the month following each payroll period. Technical detail
Semi-weekly depositors. If your lookback-period liability exceeded $50,000, you deposit semi-weekly. Wages paid Wednesday through Friday require a deposit by the following Wednesday. Wages paid Saturday through Tuesday require a deposit by the following Friday.
The $100,000 next-day rule. If you accumulate $100,000 or more in payroll taxes on any single day, the deposit is due by the next business day, regardless of your normal schedule. Hitting this threshold also bumps you to semi-weekly status for the remainder of the calendar year and the following year.
All payroll tax deposits must be made electronically through the Electronic Federal Tax Payment System (EFTPS). Paper coupons are not accepted.
Annual Filing Deadlines by Entity Type: Quick Reference
| Entity Type | Return | Due Date | Extended Due Date |
|---|---|---|---|
| Sole proprietor / Single-member LLC | Form 1040 + Schedule C | April 15 | October 15 |
| Partnership / Multi-member LLC | Form 1065 | March 15 | September 15 |
| S-Corporation | Form 1120-S | March 15 | September 15 |
| C-Corporation | Form 1120 | April 15 | October 15 |
Technical detail
What Happens When You Miss a Deadline
The IRS imposes separate penalties for different types of failures, and they stack.
Late Filing Penalties
Individual and C-Corp returns (Forms 1040, 1120). The failure-to-file penalty is 5% of unpaid taxes for each month (or partial month) the return is late, up to a maximum of 25%. If the return is more than 60 days late, the minimum penalty is the lesser of $525 or 100% of the tax owed. IRC Section 6651(a)(1). The $525 minimum applies to returns required to be filed in 2026.
Partnership returns (Form 1065). The penalty is $255 per partner per month (or partial month), up to 12 months. A five-partner LLC that files three months late owes $3,825 -- even if no tax is due on the return itself. IRC Section 6698.
S-Corp returns (Form 1120-S). The penalty is $255 per shareholder per month, up to 12 months. Same math as partnerships: the penalty multiplies by the number of owners. IRC Section 6699.
Late Payment Penalties
Failure to pay. A separate 0.5% per month penalty applies to any tax that remains unpaid after the due date, up to 25%. This runs concurrently with the late-filing penalty, though the combined monthly rate is capped at 5% when both apply. IRC Section 6651(a)(2).
Interest. The IRS charges interest on unpaid tax from the due date until paid. The rate is the federal short-term rate plus 3 percentage points, adjusted quarterly. For Q1 2026, the underpayment rate is 7% per year, compounded daily. IRC Section 6621.
Estimated Tax Underpayment Penalty
If your withholding and estimated payments fall short of the required amount, the IRS charges an underpayment penalty calculated as interest on the shortfall from each quarterly due date. The penalty runs at the same rate as general underpayment interest (7% for Q1 2026). You avoid the penalty if you paid at least 90% of current-year tax or 100% of prior-year tax (110% if prior-year AGI exceeded $150,000). IRC Section 6654.
Payroll Tax Deposit Penalties
- 1 to 5 days late: 2% of the undeposited amount
- 6 to 15 days late: 5%
- More than 15 days late: 10%
- Not paid within 10 days of an IRS notice: 15%
These tiers do not stack -- the higher rate replaces the lower one. And the IRS takes payroll taxes especially seriously because withheld income tax and the employee share of FICA are trust fund taxes. Under the Trust Fund Recovery Penalty (IRC Section 6672), responsible persons -- which includes any business owner who controls payroll -- can be held personally liable for 100% of the unpaid trust fund portion, even if the business is an LLC or corporation.
Information Return Penalties
Late or incorrect W-2s and 1099s carry their own penalties under IRC Section 6721 (failure to file with IRS) and IRC Section 6722 (failure to furnish to recipients). For 2026, the penalty is $60 per form if corrected within 30 days of the due date, $130 if corrected by August 1, and $330 per form after August 1 or if not corrected at all. The maximum annual penalty depends on business size, but for small businesses (gross receipts of $5 million or less), the caps are $220,500, $630,500, and $1,261,000 respectively.
File for an extension before the deadline passes -- even if you think you will finish on time. Extensions are free, automatic, and protect you from the late-filing penalty (5% per month). They do not extend the payment deadline, but they eliminate the most expensive penalty layer. For partnerships and S-Corps, a missed filing with no extension triggers per-owner penalties immediately.
State filing deadlines generally mirror the federal calendar, but not always. A few patterns to watch:
- Most states with an income tax follow the federal due date for the corresponding entity type
- Some states (including California and New York) require separate state-level estimated tax payments on their own schedule
- States with franchise taxes or gross receipts taxes may have entirely separate deadlines
- State payroll tax deposits (state withholding, unemployment insurance) follow state-specific schedules that rarely match the federal deposit calendar exactly
Check your state's department of revenue website or ask your CPA for a state-specific calendar. Getting the federal deadlines right and then missing a state deadline is a common first-year mistake.