Every Tax Deadline Your Business Needs to Know for 2025

Key Takeaways:

  • Staying on top of tax deadlines is crucial for businesses, with specific filing requirements varying by business structure and impacting financial health.
  • The article provides a 2025 tax deadline calendar, highlighting key dates for different forms, estimated tax payments, and filing requirements.
  • Proactive tax planning — including maintaining accurate records, setting reminders, and consulting with tax professionals — can help businesses navigate tax obligations effectively and avoid penalties.

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Missing a tax deadline isn’t just about potential penalties — it’s about protecting your business’s financial health. Proactive tax planning is your secret weapon, enabling your company to maintain clear financial records, optimize your tax strategy, and reduce the last-minute scramble that often leads to costly errors.

With the right preparation, you can transform those daunting deadlines from a source of stress to a strategic opportunity for your business.

Federal Tax Deadlines: Know What’s Relevant for Your Business

Your federal tax deadlines depend on your business structure. For instance, C corporations operating on a calendar year (January 1 to December 31) must file their federal income tax return (Form 1120) by April 15, 2025, while fiscal year corporations typically have until the 15th day of the fourth month after their fiscal year ends.

Understanding these deadlines is essential for staying compliant and avoiding penalties. If your business has complex filing requirements, consult a tax professional to clarify your obligations and meet submission deadlines.

Graphic highlighting four key federal tax dates to know in 2025: March 15, April 15, Sept 15, and Oct 15

2025 Tax Deadline Calendar

We’ve outlined key dates your business needs to know:

January 2025

January 15

  • Fourth quarter estimated tax payments for 2024 due (Form 1040-ES).

January 31

  • W-2 forms due to employees.
  • 1099 forms due to contractors.
  • Copy B of Form 3921 due to employees (for ISO exercises).
  • Form 940 (Federal Unemployment Tax Return) due.

February 2025

February 15

  • File W-2 and 1099 forms with the Social Security Administration.
  • Provide Affordable Care Act (ACA) forms to employees.

February 28

  • Paper filing deadline for Forms 1099-MISC, 1099-NEC, and W-2.
  • Paper filing deadline for Form 3921.

March 2025

March 15

  • Tax returns for S corporations (Form 1120-S) and partnerships (Form 1065) due.
  • Furnish Schedule K-1 to partners/shareholders.
  • Deadline to elect S corporation status for 2025 (Form 2553).

March 31

  • Electronic filing deadline for Form 3921.

April 2025

April 15

  • Tax returns for C corporations (Form 1120) and individuals (Form 1040) due.
  • First quarter estimated tax payments for 2025 due.
  • Deadline to file for an automatic extension (Forms 4868 or 7004).

June 2025

June 15

  • Second quarter estimated tax payments for 2025 due.

September 2025

September 15

  • Third quarter estimated tax payments for 2025 due.
  • Extended deadline for S corporations and partnerships.

October 2025 

October 15

  • Extended deadline for C corporations and individual returns.

December 2025

December 15

  • Fourth quarter estimated tax payments for corporations (fiscal year ending December 31).

January 2026

January 15

  • Final estimated tax payment for Q4 2025 due.

Important Considerations

Tax deadlines may shift if they fall on weekends or holidays, moving to the next business day. Additionally, state tax deadlines often differ, so it’s critical to check with your state’s tax authority. Working with a tax professional can help you stay compliant and adapt to any changes in tax laws or unique circumstances.

What You Can Do to Stay Ahead

Don’t let tax deadlines catch you off guard. Follow these tips:

  • Mark all relevant dates on your calendar.
  • Prepare documentation well in advance. 
  • Set up reminders for estimated tax payments.
  • Maintain accurate financial records throughout the year.
  • Consult with a tax professional for personalized guidance.

How MGO Can Help

Navigating tax deadlines doesn’t have to be overwhelming. Whether you are a private or public company with straightforward or complex filings, our team of experienced tax professionals is here to help. From filing requirements to strategic planning, we provide the guidance you need to stay compliant and focused on growing your business. Reach out to our team today and learn how we can support your success in 2025 and beyond.