Essential October 2025 Tax Deadlines for Businesses

October brings not only the refreshing chill of autumn but also crucial tax deadlines for businesses. As experts at New Beginnings One Stop Tax Help, we understand the importance of staying on top of these deadlines to ensure compliance and avoid penalties. Here’s a detailed look at the business tax due dates for October 2025.

October 15 - Corporations

Corporations with a calendar year-end must file the 2024 income tax return (Form 1120) by this date if they filed for a 6-month extension by April 15. Be sure to settle any taxes, interest, and penalties to maintain good standing.Image 1

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

Employers abiding by the monthly deposit rules should deposit the Social Security, Medicare, and any withheld income tax for September. Also, remember this is the deadline for nonpayroll withholding deposits under monthly rules.Image 2

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

Self-employed individuals who received a filing extension until October 15, 2025, must establish a Keogh Retirement Account by this date if planning contributions for 2024.

October 15 - SEP IRA & Keogh Contributions

This is also the final opportunity to fund SEP and Keogh retirement plans for calendar year 2024 for those who extended their tax filings through October 15.

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

File Form 941 for the third quarter of 2025. Ensure all taxes are deposited in line with the accuracy of deposit regulations. If the total tax liability is less than $2,500, you can pay with a timely filed return. Tax paid fully and punctually gives you until November 10 to file.

October 31 - Certain Small Employers

Small employers need to deposit any remaining tax if their yearly tax liability is $2,500 or more, but it’s below $2,500 for Q3.

October 31 - Federal Unemployment Tax

Deposit all unpaid unemployment tax accrued through September if it exceeds $500. Image 3

Weekends & Holidays:

Should any deadline fall on a weekend or a legal holiday, it is automatically moved to the next business day.

Disaster Area Extensions:

In areas designated as disaster zones, deadlines can extend further. Verify your location's status through FEMA and the IRS for any conditional extensions.

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