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Essential September 2025 Deadlines for Businesses

Staying on top of tax deadlines is crucial for businesses to ensure compliance and avoid penalties. Here’s a detailed look at the important business tax due dates in September 2025.

September 15 - S Corporations
As an S Corporation, make sure your 2024 calendar year income tax return (Form 1120-S) is filed if you utilized the automatic 6-month extension. Additionally, distribute Schedule K-1 (Form 1120-S) or its substitute, and if needed, Schedule K-3 to all shareholders.

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September 15 - Corporations
This date is pivotal for corporations to deposit the third installment of their estimated income tax for 2025. Ensure your transactions are timely to maintain good standing with tax authorities.

September 15 - Partnerships
Ensure you file your 2024 calendar year return (Form 1065) given you have received the 6-month extension. Moreover, provide each partner with their Schedule K-1 (Form 1065), or a substitute, alongside Schedule K-3 if applicable.

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September 15 - Social Security, Medicare, and Withheld Income Tax
Employers need to deposit Social Security, Medicare, and withheld income tax for August 2025 by this date if the monthly deposit rules apply, along with nonpayroll withholding deposits.

Handling Weekends & Holidays
If any tax deadline falls on a weekend or national holiday, the due date is conveniently moved to the next business day.

Extensions for Disaster Areas
Business owners in areas designated as disaster regions receive filing extensions. For the latest updates, check the following resources:
FEMA: FEMA Disaster Declarations
IRS: IRS Tax Relief in Disaster Situations

For personalized advice and to ensure you navigate these tax obligations seamlessly, consider reaching out to Michael Dolezal & Co. With over two decades of experience, we provide tailored tax solutions and business consulting services that can drive your operations forward. Contact us today at (216) 485-2028 or info@cpaneeds.com.

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