October 2025 Essential Business Tax Deadlines

October not only brings the crisp fall days but also crucial business tax deadlines. These include deadlines for corporate filings, payroll deposits, and retirement plan contributions. Staying aware of these can ensure compliance and help avoid costly penalties.

October 15 - Corporations

Corporations following a calendar year must file their 2024 income tax return (Form 1120) and settle any due taxes, interest, or penalties by this date, provided they previously filed for an automatic 6-month extension by April 15.

October 15 - Social Security, Medicare, and Withheld Income Tax

Employers needing to follow the monthly deposit rules must make their September 2025 deposits for Social Security, Medicare, and withheld income tax by October 15. This deadline also applies to nonpayroll withholding under the same deposit rules.

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October 15 - Nonpayroll Withholding
If using the monthly deposit rule, ensure tax payments made in September are deposited by this deadline.

October 15 - Last Day to Establish Keogh Account for 2024

For self-employed individuals who obtained a 6-month extension on their 2023-2024 tax returns, October 15, 2025, marks the final day to set up a Keogh Retirement Account in preparation for 2024 contributions.

October 15 - SEP IRA & Keogh Contributions

This date also acts as the deadline to make contributions to a SEP or Keogh retirement plan for 2024 if your tax return extension extends through October 15.

October 31 - Social Security, Medicare, and Withheld Income Tax

October 31 is the final date to file Form 941 for the third quarter of 2025. Make sure any undeposited tax conforms to the accuracy of deposit rules. If your tax debt is below $2,500, you can pay in full with a timely return. If all due taxes were deposited properly for the quarter, you can extend the filing until November 10.

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October 31 - Certain Small Employers
Small employers with a tax liability over $2,500 for 2025 but under $2,500 for the third quarter should deposit any outstanding tax by October 31.

October 31 - Federal Unemployment Tax (FUTA)
Deposit amounts owed through September if they exceed $500.

Weekends & Holidays:
Should a deadline fall on a weekend or legal holiday, it automatically moves to the next business day that isn't a legal holiday.

Disaster Area Extensions:
Should a region be declared a disaster area, filing deadlines will be extended. For more information on declared disaster areas and their respective filing extensions, visit the FEMA and IRS websites.

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