Key September 2025 Tax Deadlines for Small Businesses

As September 2025 approaches, it's crucial for small business owners, especially those structured as S-Corps and partnerships, to stay ahead of key tax deadlines. Navigating these due dates can ensure your financial systems remain in top shape, helping you avoid any last-minute scrambles.

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September 15 - S Corporations
If your S Corp operates on a calendar year and you filed an automatic 6-month extension, this is the date to submit Form 1120-S to report your 2024 income and settle any taxes owed. Additionally, ensure each shareholder receives their Schedule K-1 (Form 1120-S) or a substitute, including Schedule K-3 if applicable.

September 15 - Corporations
This deadline marks the third installment for the 2025 estimated income tax for corporations. Meeting this requirement keeps you on track and avoids potential penalties.

September 15 - Partnerships
For partnerships with a 2024 calendar year and a granted 6-month extension, ensure you file Form 1065 and deliver Schedule K-1 (and K-3 if necessary) to each partner.

September 15 - Social Security, Medicare, and Withheld Income Tax
Employers who adhere to monthly deposit rules must file their August 2025 Social Security, Medicare, and withheld income taxes by this date. The same deadline applies for nonpayroll withholding deposits.

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Planning Around Weekends & Holidays
If any due date lands on a weekend or legal holiday, the deadline automatically shifts to the next business day.

Recognizing Disaster Area Extensions
In the event of a disaster declaration by FEMA, tax due dates receive extensions. Stay informed by visiting FEMA and the IRS for updates.

By proactively managing these September deadlines, you're not only complying with regulations but also enhancing your financial resilience. For more personalized guidance tailored to your business concerns, reach out to Freedom Line Accounting & Tax. Let us illuminate a path to financial clarity and freedom! Ask us how this applies to your business by booking a consultation here.

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