Essential October 2025 Tax Deadlines for Businesses

As October brings in the crisp fall air, it also brings critical business tax deadlines. These include corporate filings, payroll deposits, and retirement plan contributions. Staying on top of these key dates ensures compliance and helps you avoid costly penalties.

October 15: Corporate Tax Returns

Corporations must file their 2024 calendar year income tax return (Form 1120) and settle any due taxes, interest, and penalties by this date. This deadline is applicable if a 6-month extension was filed by April 15.

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October 15: Payroll Tax Deposits

Employers must deposit Social Security, Medicare, and withheld income tax for September if the monthly deposit rule applies. This also applies to nonpayroll withholding deposits for September.

October 15: Nonpayroll Withholding

Ensure your deposits for any payments in September meet the monthly deposit rule.

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October 15: Retirement Plans

Self-employed individuals with a 6-month extension must establish a Keogh Retirement Account by this date if they plan to contribute for 2024. It’s also the last day to contribute to SEP or Keogh plans, contingent on tax extensions.

October 31: Quarterly Payroll Tax Filings

File Form 941 for the third quarter of 2025, handling any undeposited tax per accuracy deposit rules. If your liability is under $2,500, full payment with the filing is possible. Otherwise, timely full deposits allow filing up until November 10.

October 31: Employer Deposits & Federal Unemployment Tax

Small employers must deposit remaining taxes if their annual liability is $2,500 or more, but less than $2,500 for the third quarter. Additionally, employers must deposit Federal Unemployment Tax due through September if it exceeds $500.

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Weekend & Holiday Extensions

If a deadline falls on a weekend or a holiday, it extends to the next business day that isn’t a holiday.

Disaster Area Extensions

Deadlines are extended for areas designated as disaster zones. For updates on disaster areas and related extensions, visit FEMA and IRS websites.

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