Essential October 2025 Business Tax Deadlines

October brings the refreshing change of fall along with vital tax deadlines crucial for businesses. From corporate filings to retirement contributions, understanding these dates is key to staying compliant and avoiding penalties.

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October 15 - Corporations

Submit your 2024 calendar year income tax return (Form 1120) and remit any taxes, interest, and penalties if you timely secured an automatic 6-month extension by April 15.

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

Employers following the monthly deposit schedule must deposit Social Security, Medicare, and withheld income tax for September 2025 by this date. This also covers nonpayroll withholding if the monthly deposit rule is applicable.

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October 15 - Nonpayroll Withholding

If the monthly deposit rule applies, ensure taxes for September payments are deposited by this deadline.

October 15 - Last Day to Establish a Keogh Account for 2024

For self-employed individuals granted a 6-month extension for their 2023 tax returns, October 15, 2025, is the final day to set up a Keogh Retirement Account for 2024 contributions.

October 15 - SEP IRA & Keogh Contributions

The last opportunity to contribute to a SEP or Keogh plan for the 2024 tax year, should your filing extension last until October 15.

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

File Form 941 for the third quarter of 2025. Deposit any outstanding taxes according to the deposit rules. Liabilities under $2,500 can be paid in full with a prompt return. If payment for the quarter was on schedule and complete, the filing deadline extends to November 10.

October 31 - Certain Small Employers

Deposit outstanding taxes if your liability is $2,500 or more for the year but less than $2,500 for the third quarter.

October 31 - Federal Unemployment Tax

Deposit any taxes due through September if they exceed $500.

Weekends & Holidays:

Deadlines falling on weekends or legal holidays extend to the next business day.

Disaster Area Extensions:

Areas designated as disaster zones receive extended due dates. Check the following resources:FEMA: FEMA Disaster Declarations
IRS: IRS Disaster Relief

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