The Complete 2026 Federal Tax Calendar Every Small Business Owner Needs
Missing a single tax deadline can cost your business hundreds—or even thousands—of dollars in penalties and interest. The IRS charges a failure-to-file penalty of 5% of unpaid taxes for each month your return is late, and underpayment penalties on missed estimated tax installments add up fast. Yet every year, small business owners get caught off guard by deadlines they didn't know existed.
The truth is that "tax season" isn't just January through April. For small business owners, tax obligations run year-round: quarterly estimated payments, information returns, employment tax filings, and annual returns each have their own deadlines. Missing any of them creates a cascade of problems that goes far beyond the penalty itself.
This guide lays out every critical federal tax deadline for 2026, organized month by month, so you can plan ahead and turn tax compliance from a source of stress into a manageable routine.
January 2026: Start the Year Right
January sets the tone for your entire tax year. Several important deadlines hit early.
January 15 — Fourth-quarter 2025 estimated tax payment is due (Form 1040-ES). If you're a sole proprietor, freelancer, or partner who owes estimated taxes, this is your last installment for the prior tax year. You can skip this payment if you file your 2025 return and pay the full balance by February 2.
January 31 — Employers must furnish Form W-2 to all employees. Businesses must also send Form 1099-NEC to independent contractors paid $600 or more during 2025. Since January 31 falls on a Saturday in 2026, the actual deadline shifts to February 2.
What to Do This Month
- Gather all income and expense records from 2025
- Reconcile your bank and credit card statements against your bookkeeping records
- Verify that contractor and employee information is accurate for W-2 and 1099 preparation
- Review your estimated tax payments from 2025 to determine if you underpaid
February 2026: Information Returns
February 2 — Extended deadline for furnishing W-2s and 1099-NECs (due to the January 31 Saturday). These forms must also be filed with the Social Security Administration (W-2) and the IRS (1099-NEC) by this date.
February 28 — If filing on paper, Forms 1099-MISC, 1099-INT, 1099-DIV, and other information returns are due to the IRS. The deadline extends to March 31 if you file electronically.
What to Do This Month
- Confirm all W-2s and 1099s have been sent and filed
- Begin organizing your business tax return documentation
- Schedule time with your tax preparer or CPA if you use one
March 2026: Partnership and S Corp Returns
March 16 — Tax returns are due for partnerships (Form 1065) and S corporations (Form 1120-S). The standard deadline is March 15, but since that falls on a Sunday in 2026, the deadline moves to Monday, March 16. Schedule K-1s must also be provided to partners and shareholders by this date.
If you need more time, file Form 7004 for an automatic six-month extension. An extension gives you until September 15 to file, but it does not extend the time to pay any tax owed.
What to Do This Month
- File partnership and S corp returns or request an extension
- Distribute K-1s to all partners and shareholders
- Begin preparing your personal tax return using K-1 information
April 2026: Tax Day and Beyond
April 15 is the most important date on the tax calendar, with multiple deadlines converging on the same day.
April 15 — This single date carries several obligations:
- Individual income tax returns (Form 1040) are due for 2025
- C corporation returns (Form 1120) are due for 2025
- Sole proprietor returns are due (filed on Schedule C with Form 1040)
- First-quarter 2026 estimated tax payment is due (Form 1040-ES)
- Tax extension requests must be filed (Form 4868 for individuals, Form 7004 for corporations)
- Last day for 2025 IRA contributions (traditional and Roth)
- Last day for 2025 HSA contributions
Understanding Extensions
Filing an extension gives you six additional months to submit your return, but it does not extend your payment deadline. You must estimate and pay any tax owed by April 15 to avoid interest and penalties. Think of an extension as extra time to prepare paperwork, not extra time to pay.
What to Do This Month
- File all due returns or request extensions
- Make your first estimated tax payment for 2026
- Fund retirement accounts (IRA) and health savings accounts (HSA) for 2025
- Set calendar reminders for upcoming quarterly payment deadlines
June 2026: Second Quarter Estimated Taxes
June 15 — Second-quarter 2026 estimated tax payment is due. This covers income earned from April 1 through May 31. Despite covering only two months of income, the payment amount is typically calculated as one-quarter of your annual estimated tax liability.
What to Do This Month
- Calculate your estimated tax payment based on year-to-date income
- Adjust your estimates if your income has changed significantly from your initial projections
- Review your mid-year financial position and consider whether your withholding or estimated payments are on track
September 2026: Third Quarter and Extended Returns
September brings two major deadlines in the same week.
September 15 — Third-quarter 2026 estimated tax payment is due. This payment covers income earned from June 1 through August 31.
September 15 — Extended deadline for partnership (Form 1065) and S corporation (Form 1120-S) returns. If you filed an extension in March, your return is due now.
What to Do This Month
- File any extended partnership or S corp returns
- Make your third estimated tax payment
- Begin year-end tax planning: review your projected annual income and identify deductions you can still claim or accelerate
October 2026: Extended Individual and C Corp Returns
October 15 — Extended deadline for individual income tax returns (Form 1040) and C corporation returns (Form 1120). If you requested an extension in April, your return must be filed by this date.
What to Do This Month
- File all remaining extended returns
- Review any penalties or interest that may have accrued if you underpaid in April
- Start thinking about year-end tax strategies for the current year
December 2026: Year-End Planning
December 15 — Fourth-quarter 2026 estimated tax payment is due for C corporations only. Individual and pass-through entity owners have until January 15, 2027.
December 31 — Last day to take many tax-reducing actions for the 2026 tax year:
- Make business purchases that qualify for Section 179 deductions (up to $2.56 million in 2026)
- Contribute to employer-sponsored retirement plans (401(k), SEP IRA employer contributions)
- Prepay deductible expenses if it benefits your tax position
- Make charitable contributions
What to Do This Month
- Maximize deductions before year-end
- Run a preliminary tax projection to estimate your 2026 liability
- Ensure your bookkeeping is current so January preparation goes smoothly
Key 2026 Tax Changes That Affect Your Calendar
Several tax law changes in 2026 affect how much you owe and what you can deduct:
SALT deduction cap increase — The state and local tax deduction cap rises from $10,000 to $40,000 in 2026, a significant change for business owners in high-tax states.
QBI deduction becomes permanent — The qualified business income deduction (20% of pass-through income) is now permanent, with a minimum deduction of $400 for taxpayers with at least $1,000 in QBI.
Section 179 expansion — The immediate expensing limit increases to $2.56 million for qualifying business equipment and property purchases.
HSA contribution limits — Individual HSA contributions rise to $4,400 and family coverage to $8,750, offering additional tax-advantaged savings opportunities.
These changes may affect your quarterly estimated tax calculations. If you're used to paying the same amount each quarter, recalculate based on the new rules.
How to Never Miss a Tax Deadline
Set Up a Quarterly Review System
Instead of thinking about taxes once a year, build a quarterly habit:
- After each quarter ends, review your income and expenses for the period
- Calculate your estimated tax payment based on actual results, not last year's numbers
- Make the payment at least a week before the deadline to account for processing time
- Update your projections for the rest of the year
Use the Safe Harbor Rule
If you pay at least 100% of last year's total tax liability through estimated payments and withholding (110% if your adjusted gross income exceeded $150,000), you won't face underpayment penalties—even if you owe more when you file. This "safe harbor" rule gives you a predictable floor for your quarterly payments.
Keep Your Records Current
The single biggest cause of tax season stress is catching up on months of unfiled receipts and unreconciled transactions. Maintaining your financial records in real time—or at least monthly—eliminates the frantic scramble and reduces the chance of missing deductions.
Know When to Get Help
Tax software works well for straightforward businesses with single-state operations. But if you have employees in multiple states, complex entity structures, significant investment income, or international transactions, a CPA or enrolled agent can save you money by finding strategies you'd miss on your own.
Quick Reference: 2026 Federal Tax Deadline Summary
| Date | Deadline |
|---|---|
| Jan 15 | Q4 2025 estimated tax payment |
| Feb 2 | W-2 and 1099-NEC due (to recipients and IRS) |
| Mar 16 | Partnership and S corp returns due |
| Mar 31 | Electronic filing deadline for 1099-MISC and other information returns |
| Apr 15 | Individual and C corp returns due; Q1 2026 estimated tax; extension deadline |
| Jun 15 | Q2 2026 estimated tax payment |
| Sep 15 | Q3 2026 estimated tax; extended partnership/S corp returns due |
| Oct 15 | Extended individual and C corp returns due |
| Dec 15 | Q4 2026 estimated tax (C corps only) |
| Dec 31 | Last day for most 2026 tax-reducing actions |
Stay on Top of Your Tax Obligations
The difference between business owners who dread tax season and those who handle it confidently comes down to one thing: staying organized year-round. When your financial records are current and your deadlines are mapped out in advance, tax compliance becomes a routine part of running your business rather than an annual crisis.
Beancount.io provides plain-text accounting that gives you complete visibility into your business finances—every transaction tracked, every category organized, and everything version-controlled so you always know exactly where your money went. Get started for free and make your next tax season the easiest one yet.
