Missed deadlines are rarely a knowledge problem. The business knew the date existed; nobody owned it, or it was on a list that lived in one person's inbox.
A calendar only works when it reflects your business rather than a generic set of dates. Your entity type sets the return dates, employees add payroll dates, taxable sales add filings in each state you are registered in, and the state of formation adds its own annual requirement.
This covers the year month by month, the quarterly cycle that runs alongside it, how to build the version that applies to you, and what to do when a date has already passed.
How to Use This Calendar
This calendar covers the key federal tax deadlines for small businesses in 2026. When a deadline falls on a weekend or federal holiday, it moves to the next business day. Confirm exact dates with your CPA or check IRS.gov as the calendar year unfolds.
A generic calendar is a prompt to build yours, not a substitute for it. Your entity type sets the return dates, employees add payroll dates, taxable sales add filings in every state you are registered in, and the state of formation adds its own. Name one person to own each date.
Anu Gupta, CA, EA, B.Tech · LinkedInJanuary 2026
| Date | Deadline |
|---|---|
| January 15 | Q4 2025 estimated tax payment due (Form 1040-ES). Can skip if filing and paying full balance by January 31. |
| January 31 | Send W-2 forms to employees, must be mailed/emailed to recipients. |
| January 31 | Send 1099-NEC to non-employee contractors who received $600+ in 2025. |
| January 31 | Form 940 (FUTA annual return) due if all FUTA deposits were made on time; otherwise January 31 is also the payment date. |
| January 31 | Form 941 Q4 2025, if you deposited all taxes when due, the deadline is February 10. |
February 2026
| Date | Deadline |
|---|---|
| February 18 | If you requested 30-day extension on Form 1099-MISC (with Box 8 or Box 10 only): extended deadline. |
| February 28 | Paper filing of 1099 forms to IRS (1099-MISC, 1099-INT, 1099-DIV, etc.) if you have fewer than 250 forms. |
March 2026
| Date | Deadline |
|---|---|
| March 15 | S-corporation (Form 1120-S) and partnership (Form 1065) returns due. This is also the deadline for S-corp and partnership to issue K-1s to partners/shareholders. |
| March 15 | Deadline to elect S-corporation status for tax year 2026 (Form 2553, within 2.5 months of start of tax year). |
| March 31 | Electronic filing of 1099 forms to IRS (lower threshold than paper; mandatory if filing 10+ forms as of 2024). |
April 2026
| Date | Deadline |
|---|---|
| April 15 | Individual income tax return (Form 1040) due. |
| April 15 | C-corporation (Form 1120) return due (for calendar-year corporations). |
| April 15 | Q1 2026 estimated tax payment due (Form 1040-ES). |
| April 15 | File Form 4868 for automatic 6-month individual extension (to October 15). Pay estimated balance due. |
| April 15 | File Form 7004 for automatic 6-month extension for C-corps. |
| April 15 | IRA contribution deadline for tax year 2025 (traditional and Roth IRA). |
| April 30 | Form 941 Q1 2026 payroll tax return due. |
June 2026
| Date | Deadline |
|---|---|
| June 15 | Q2 2026 estimated tax payment due. |
| June 15 | US citizens living abroad: Form 1040 due (automatic 2-month extension; interest still accrues from April 15). |
July 2026
| Date | Deadline |
|---|---|
| July 31 | Form 941 Q2 2026 payroll tax return due. |
| July 31 | Form 5500 due for calendar-year employee benefit plans (401k, SIMPLE IRA with 100+ participants). |
September 2026
| Date | Deadline |
|---|---|
| September 15 | Q3 2026 estimated tax payment due. |
| September 15 | Extended deadline for S-corporations (Form 1120-S) and partnerships (Form 1065) that filed for extension in March. |
| September 15 | SEP-IRA contribution deadline for partnerships that filed for extension. |
October 2026
| Date | Deadline |
|---|---|
| October 15 | Extended deadline for individual income tax returns (Form 1040). |
| October 15 | SEP-IRA contribution deadline for sole proprietors who filed for extension. |
| October 15 | Extended deadline for C-corporations (Form 1120) with April 15 original deadline. |
| October 31 | Form 941 Q3 2026 payroll tax return due. |
December 2026
| Date | Deadline |
|---|---|
| December 15 | C-corporation Q4 estimated tax deposit (corporate estimated tax, different from individual schedule). |
| December 31 | Last day to establish a Solo 401(k) plan for 2026 (must be adopted by year-end). |
| December 31 | Year-end: make retirement contributions, purchase qualifying equipment for Section 179, execute timing strategies. |
Quarterly Estimated Tax Payment Schedule
Self-employed individuals and business owners who expect to owe $1,000 or more in tax must pay quarterly estimates:
| Quarter | Payment Due |
|---|---|
| Q1 (Jan-Mar income) | April 15, 2026 |
| Q2 (Apr-May income) | June 15, 2026 |
| Q3 (Jun-Aug income) | September 15, 2026 |
| Q4 (Sep-Dec income) | January 15, 2027 |
Pro Tip: Underpaying estimates by more than a threshold triggers a penalty (Form 2210). Safe harbor: pay 100% of prior year tax (110% if prior year AGI exceeded $150,000) to avoid underpayment penalty regardless of actual current-year liability.
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Frequently Asked Questions
What happens if I miss a deadline?
Late filing penalty: 5% of unpaid tax per month (maximum 25%). Late payment penalty: 0.5% per month. Interest also accrues. File even if you cannot pay, the failure-to-file penalty is far worse than failure-to-pay.
Are state tax deadlines the same as federal?
Most states conform to federal individual deadlines (April 15, October 15 extension), but business entity deadlines vary. California, New York, and some other states have their own calendars. Check your state's revenue department.
How do we build a calendar that is right for our business?
Start from what the business actually is and does, then attach dates to it. The entity type sets the return dates, having employees adds payroll dates, selling taxable goods or services adds filing dates in each state you are registered in, and the state of formation adds its own annual requirement. A generic calendar is a prompt to build yours, not a substitute for it.
Who should own these dates internally?
One named person, with a second who can cover, and each date recorded with who prepares it and who approves it. Where the work is done by an external adviser, the internal owner is still accountable for the date being met, because the obligation belongs to the business. A shared calendar owned by nobody is the most common reason a deadline passes unnoticed.
What should happen when a deadline is missed?
File as soon as possible rather than waiting for the position to be perfect, because in most cases the consequences of failing to file are worse than those of failing to pay on time. Pay what you can alongside it, and deal with the balance through whatever arrangement is available. Then find out why the date was missed, because a missed deadline is almost always a process failure rather than a one-off.
Written by
Anu Gupta, CA, EA, B.Tech
Anu works with US businesses on tax and entity questions at Profitjets, from choosing a structure to the filings that follow it. She writes about the decisions owners make once and then live with for years. Connect on LinkedIn
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