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October 2026 Business Due Dates

October includes several important tax deadlines for businesses and self-employed individuals. Be sure to review upcoming filing, payroll tax deposit, and retirement plan deadlines to determine which may apply to you.

October 15 - Corporations

File a 2025 calendar year income tax return (Form 1120) and pay any tax, interest, and penalties due. This due date applies only if you timely requested an automatic 6-month extension by April 15.

October 15 - Social Security, Medicare and Withheld Income Tax

If the monthly deposit rule applies, deposit the tax for payments in September.

October 15 - Nonpayroll Withholding

If the monthly deposit rule applies, deposit the tax for payments in September.

October 15 - Last Day to Establish a Keogh Account for 2025

If you received an automatic 6-month extension of time to file your 2025 tax return and are self-employed, October 15, 2026, is the last day to establish a Keogh Retirement Account if you plan to make a contribution for 2025.

October 15 - SEP IRA & Keogh Contributions

Last day to contribute to a SEP or Keogh retirement plan for calendar year 2025 if your tax return is on extension through October 15.

Weekends & Holidays:

If a due date falls on a Saturday, Sunday or legal holiday, the due date is automatically extended until the next business day that is not itself a legal holiday.

Disaster Area Extensions:

Please note that when a geographical area is designated as a disaster area, due dates will be extended. For more information whether an area has been designated a disaster area and the filing extension dates visit the following websites:

FEMA: https://www.fema.gov/disaster/declarations
IRS: https://www.irs.gov/newsroom/tax-relief-in-disaster-situations

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