Small Business Tax Deadlines You Can’t Afford to Miss

Staying compliant without losing your mind (or your money).

Running a small business means wearing many hats—owner, marketer, customer service, and yes, even part-time tax expert. But when it comes to taxes, ignorance isn’t bliss—it can be costly. Missing a key deadline can result in penalties, interest, or worse, draw unnecessary attention from the IRS.

To help you stay ahead and stress less, here’s a guide to the essential federal tax deadlines small business owners need to know. This is based on information from the IRS, the U.S. Small Business Administration (SBA), and other reputable sources as of 2025.

🗓️ Key Federal Tax Deadlines for Small Businesses

While specific deadlines can vary based on your business structure and fiscal year, here are the major dates most small business owners should keep on their radar:

January 31 – W-2s and 1099-NECs Due

• What’s due:

  • Send W-2s to employees

  • Send Form 1099-NEC to independent contractors paid $600 or more

  • File copies with the IRS and Social Security Administration

Why it matters: The IRS uses this data to match income reporting. Late filing can lead to penalties ranging from $60 to $310 per form (IRS.gov, 2025).

March 15 – Tax Deadline for S Corps and Partnerships

• What’s due:

  • Form 1120-S for S corporations

  • Form 1065 for partnerships

  • Provide Schedule K-1 to shareholders or partners

Pro tip: If you need more time, file Form 7004 for a 6-month extension. But remember, an extension to file is not an extension to pay.

April 15 – Tax Deadline for Sole Proprietors, LLCs (Single Member), and C Corps

• What’s due:

  • Sole proprietors and single-member LLCs: Schedule C with your Form 1040

  • C corporations: Form 1120

  • First installment of estimated taxes for the year

Why it matters: Missing this deadline can lead to failure-to-file and failure-to-pay penalties—up to 25% of your unpaid taxes, according to the IRS.

Estimated Quarterly Tax Payments (Form 1040-ES or 1120-W)

If you expect to owe $1,000 or more in taxes for the year (after withholding), you’re likely required to pay quarterly estimated taxes.

• Deadlines for calendar-year businesses:

  • April 15

  • June 17

  • September 16

  • January 15 (following year)

Tip: Use IRS Form 1040-ES worksheets or accounting software to calculate your estimated payments accurately.

September 16 – Extended Deadline for S Corps and Partnerships

If you filed for a 6-month extension in March, this is your final due date to submit your tax return.

October 15 – Extended Deadline for Sole Proprietors and C Corps

If you filed for a personal or corporate extension in April, this is your last day to file.

🧾 Other Tax Filing Responsibilities to Watch For

• State and Local Taxes: Deadlines vary by state—sales tax, franchise tax, and employment taxes all come with their own due dates. Check with your state's Department of Revenue.

• Payroll Taxes: If you have employees, you’ll need to deposit payroll taxes regularly (semi-weekly or monthly), and file Form 941 quarterly.

You can find a full breakdown on IRS.gov, or use IRS Publication 509: Tax Calendars for Use in 2025.

✅ How to Stay on Track Without Losing Sleep

1. Use a Tax CalendarThe IRS offers downloadable calendars, and many accounting tools like QuickBooks, Xero, and Bench offer deadline reminders.

2. Work with a ProA CPA or Enrolled Agent can help ensure nothing slips through the cracks—and may save you money in deductions and strategy.

3. Set Aside Funds RegularlyAvoid surprises by saving a portion of your income each month for taxes (a general rule is 25–30% of net income for small businesses).

4. Don’t Wait Until the Last MinuteFiling early can help you spot issues and avoid a last-minute scramble—especially if you’re expecting a refund or need to resolve discrepancies.

💡 Final Thought: Taxes Aren’t Fun, But They Don’t Have to Be Frightening

Staying compliant with tax deadlines doesn’t require you to become a tax expert—but it does require staying organized and proactive. With a clear calendar and a little help, you can avoid penalties, keep your business in good standing, and focus on what really matters—growing your business.