2026 Tax Deadlines Every Small Business Owner Needs to Know

Tax deadlines are not suggestions. Missing them can result in late filing penalties, late payment penalties, and interest charges that compound quickly. The IRS charges a failure-to-file penalty of 5% of unpaid taxes per month (up to 25%) and a failure-to-pay penalty of 0.5% per month. For a business that owes $20,000, a three-month delay could cost $3,300 in penalties alone. Here is your complete 2026 tax deadline calendar.

January 2026

January 15: Fourth quarter 2025 estimated tax payment is due (Form 1040-ES). If you are a sole proprietor, LLC member, or S-Corp shareholder who makes quarterly estimated payments, this is your final installment for the 2025 tax year. January 31: Employers must furnish W-2 forms to all employees and file W-2s with the Social Security Administration. 1099-NEC forms for independent contractors paid $600 or more must also be filed with the IRS and furnished to recipients by this date. Quarterly payroll taxes for Q4 2025 are due (Form 941).

February 2026

February 28: If filing on paper, 1099-MISC, 1099-INT, 1099-DIV, and other information returns (except 1099-NEC) are due to the IRS. The electronic filing deadline is March 31. Note that 1099-NEC has a separate January 31 deadline.

March 2026

March 16: Tax returns for S-Corporations (Form 1120-S) and Partnerships (Form 1065) are due. These are due on the 15th day of the third month after the fiscal year-end. For calendar-year entities, that is March 15, but in 2026, March 15 falls on a Sunday, so the deadline moves to Monday, March 16. If you cannot file on time, file Form 7004 for an automatic six-month extension (extending the deadline to September 15). Remember: an extension to file is not an extension to pay. Estimated taxes are still due by the original deadline.

April 2026

April 15: Individual income tax returns (Form 1040) and C-Corporation returns (Form 1120) are due. This is also the deadline for first quarter 2026 estimated tax payments. For individuals and C-Corps that need more time, file Form 4868 (individuals) or Form 7004 (corporations) for an automatic extension. IRA and HSA contributions for the 2025 tax year must be made by this date. SEP-IRA contributions are due by the tax filing deadline, including extensions.

June 2026

June 15: Second quarter 2026 estimated tax payment is due. This is also the deadline for U.S. citizens and resident aliens living abroad to file their 2025 individual tax returns (an automatic two-month extension applies). However, interest on any unpaid taxes runs from the original April 15 deadline.

July 2026

July 31: Quarterly payroll tax return (Form 941) for Q2 is due. Employers must also deposit Federal Unemployment Tax (FUTA) if the liability exceeds $500.

September 2026

September 15: Third quarter 2026 estimated tax payment is due. Extended S-Corporation and Partnership tax returns are due (if you filed Form 7004 in March). This is the final deadline for these entity types.

October 2026

October 15: Extended individual tax returns (Form 1040) and extended C-Corporation returns (Form 1120) are due. This is your absolute final deadline if you filed for an extension in April.

Payroll Tax Deadlines Throughout the Year

If you have employees, you must deposit federal income tax withholding, Social Security tax, and Medicare tax either semi-weekly or monthly, depending on your deposit schedule. Form 941 (quarterly payroll tax return) is due by the last day of the month following the end of each quarter: April 30, July 31, October 31, and January 31. Form 940 (annual FUTA tax return) is due by January 31 of the following year.

Tips to Avoid Penalties

Set up calendar reminders at least two weeks before each deadline. Use the IRS Electronic Federal Tax Payment System (EFTPS) for estimated payments and payroll deposits. Consider making estimated payments quarterly even if your income is uneven, as it is easier to adjust than to face a large underpayment penalty. Work with your CPA to calculate safe harbor estimated payments (paying 100% of your prior year tax liability, or 110% if your AGI exceeded $150,000). If you cannot pay the full amount owed, file your return on time anyway. The failure-to-file penalty is ten times higher than the failure-to-pay penalty.