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October 2025 Essential Business Tax Deadlines

October brings not only the vibrant hues of fall but also significant deadlines for business tax compliance. It's crucial for corporations, employers, and self-employed individuals to keep abreast of these deadlines to avoid hefty penalties and ensure seamless operations. Here's a detailed guide to essential tax-related dates in October 2025 you shouldn't miss.

October 15 - Mandatory Corporate Filings

For corporations operating on a calendar year, this is the ultimate deadline to file your 2024 income tax return (Form 1120). Ensure all taxes, interest, and penalties are settled. Note that this deadline is applicable only if an automatic 6-month filing extension was obtained by April 15.

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October 15 - Employer Tax Responsibilities

Employers adhering to the monthly deposit schedule should ensure their Social Security, Medicare, and withheld income taxes for September 2025 are deposited by this date. Additionally, if your monthly deposit rule for nonpayroll withholding is applicable, the same deadline applies.

October 15 - Secure Your Retirement Plans

This date is also the deadline for self-employed individuals who extended their 2023 tax return filing to establish a Keogh retirement account for the year 2024. Furthermore, it's the last chance to contribute to SEP or Keogh retirement plans if your tax return extension is through October.

October 31 - Quarterly Employer's Tax Reporting

Form 941 for Q3 2025 must be filed by this date. All undeposited taxes must comply with the accuracy of deposit rules. Employers with a tax liability under $2,500 can opt to pay in full with a timely filed return. If taxes were deposited timely and fully, filing by November 10 is permissible.

October 31 - Additional Employer Payment Duties

Employers with a 2025 tax liability over $2,500 but under $2,500 for Q3 must deposit any undeposited amounts on this date. For those addressing the Federal Unemployment Tax, ensure deposits are made for amounts exceeding $500 through September.

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Weekend and Holiday Adjustments

Financial compliance adheres to a simple rule: if a deadline falls on a weekend or legal holiday, the due date is adjusted to the following business day.

Considerations for Disaster-Impacted Areas

The IRS and FEMA offer deadline extensions for disaster-stricken regions. For updated details on any disaster declarations and associated tax relief, visit FEMA's Disaster Declarations and the IRS's Tax Relief page.

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