October ushers in cool fall days and critical business tax deadlines—from corporate filings and payroll deposits to retirement plan contributions. Review these key dates to stay compliant and avoid penalties.
October 15 – Corporations
File a 2024 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 you are an employer and the monthly deposit rules apply, October 15 is the due date for you to make your deposit of Social Security, Medicare, and withheld income tax for September 2025. This is also the due date for the nonpayroll withholding deposit for September 2025 if the monthly deposit rule applies.
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 2024
If you received an automatic 6-month extension of time to file your 20232024 tax return and are self-employed, October 15, 2025, is the last day to establish a Keogh Retirement Account if you plan to contribute for 2024.
October 15 – SEP IRA & Keogh Contributions
Last day to contribute to a SEP or Keogh retirement plan for calendar year 2024if tax return is on extension through October 15.
October 31 – Social Security, Medicare and Withheld Income Tax
File Form 941 for the third quarter of 2025. Deposit or pay any undeposited tax under the accuracy of deposit rules. If your tax liability is less than $2,500, you can pay it in full with a timely filed return. If you deposited the tax for the quarter in full and on time, you have until November 10 to file the return.
October 31 – Certain Small Employers
Deposit any undeposited tax if your tax liability is $2,500 or more for 2025 but less than $2,500 for the third quarter.
October 31 – Federal Unemployment Tax
Deposit the tax owed through September if more than $500.
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
