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Key October 2025 Tax Deadlines for Businesses

As we enter October's crisp and transformative season, businesses must also brace for significant tax obligations—from corporate tax returns to retirement plan deadlines. Missing these crucial deadlines can lead to penalties, so our clients in the Maryland, Virginia, and District of Columbia areas should pay close attention to these key dates to maintain compliance and optimize their financial strategies.

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October 15 - Corporate Tax Returns
If your corporation filed a calendar-year tax return extension (Form 1120) back in April 2024, this is the final call to submit your return. It’s also the time to clear any outstanding balances, including taxes, interest, and penalties.

October 15 - Payroll Taxes
For businesses following the monthly deposit rules, Social Security, Medicare, and income tax withholdings for September 2025 are due. This also covers the nonpayroll withholding for the same period.

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October 15 - Establishing a Keogh Plan
Self-employed individuals who are setting up a Keogh Retirement Account with a 20232024 tax extension have until this date to establish their account for 2024 contributions.

October 31 - Quarterly Payroll Form 941
Businesses should file Form 941 for the third quarter of 2025. If taxes were fully deposited timely, you are allowed to defer filing until November 10. For minor tax liabilities (under $2,500), full payment with the return is an option.

October 31 - Small Employer Obligations
For small employers with tax liabilities between $2,500 and less than $2,500 for the third quarter, ensure all taxes are deposited as required by federal regulations.

October 31 - Federal Unemployment Tax
If your liability exceeds $500 through September, make the necessary federal unemployment deposits.

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Important Considerations
Note that deadlines falling on weekends or public holidays extend to the next business day, minimizing disruption to your tax plans. Additionally, in federally recognized disaster zones, the IRS may grant extensions. For more information on these extensions, check FEMA and IRS resources.

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