October 2025 Essential Business Tax Deadlines

As October brings a breath of crisp autumn air, it also delivers crucial tax deadlines for businesses. From corporate filings to vital payroll deposits and retirement contributions, keeping abreast of these important dates ensures compliance and helps you sidestep penalties.

October 15 - Corporations

Corporations operating on a calendar year must file their 2024 income tax return (Form 1120) and settle any tax, interest, and penalties due, provided an automatic six-month extension was requested by April 15.

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

If your business is subject to monthly deposit rules, October 15 is your deadline to deposit Social Security, Medicare, and withheld income taxes for September 2025. The same date applies to nonpayroll withholding deposits for September.

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October 15 - Nonpayroll Withholding

Ensure that if your business is part of the monthly deposit cycle, the tax for September payments is deposited by this date.

October 15 - Last Day for Keogh Account Setup for 2024

If you’re self-employed and have an extension for your 2023-2024 tax return, October 15 is your final opportunity to establish a Keogh Retirement Account to contribute for 2024.

October 15 - SEP IRA & Keogh Contributions

For those with tax return extensions through October 15, this is also the last day to make contributions to a SEP or Keogh plan for the calendar year 2024.

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

Submit Form 941 for Q3 2025. If undeposited tax remains, deposit according to accuracy of deposit rules. Businesses with liabilities under $2,500 can pay in full with a timely filed return, but should all deposits be timely and complete, filing is extended until November 10.

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October 31 - Certain Small Employers

Deposit any outstanding taxes if your total liability exceeds $2,500 for the year yet is under $2,500 for Q3.

October 31 - Federal Unemployment Tax

Deposit taxes owed through September if the total exceeds $500.

Extensions for Weekends & Holidays

Should any due date coincide with a Saturday, Sunday, or legal holiday, extensions automatically apply until the next business day.

Extensions for Disaster Areas

Note that designated disaster areas automatically receive extended timelines for filing. For current declarations, visit the following resources:
FEMA: https://www.fema.gov/disaster/declarations
IRS: https://www.irs.gov/newsroom/tax-relief-in-disaster-situations

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