Key Tax Deadlines for September 2025

As the summer heat fades, September 2025 brings critical deadlines for businesses, particularly in the realm of tax compliance. As your trusted accounting partner, MJ Ahmed CPA PLLC ensures you're prepared for these deadlines, emphasizing the importance of timely tax management.

September 15 - S Corporations
S corporations with a calendar year must file their 2024 income tax return (Form 1120-S) by this date, provided an automatic 6-month extension was secured. Ensure that each shareholder is provided their Schedule K-1 or a substitute Schedule K-1, and, where applicable, Schedule K-3 to maintain compliance.Image 1

September 15 - Corporations
Corporations should deposit their third installment of 2025 estimated income tax. It's a crucial step in ensuring you remain on track with your financial obligations.Image 2

September 15 - Partnerships
For partnerships operating on a calendar year, this date is the deadline to file their 2024 return (Form 1065) if they received a 6-month extension. Partners should receive their Schedule K-1 or a substitute, including Schedule K-3 if necessary.

September 15 - Social Security, Medicare, and Withheld Income Tax
Employers who adhere to monthly deposit rules must deposit their contributions for August 2025 by this date. This deadline also applies to nonpayroll withholding for the same period. Ensuring you're up-to-date with these deposits is essential to avoid penalties.Image 3

Weekends & Holidays:
Should any deadline fall on a weekend or legal holiday, the deadline is extended to the next business day that is not a holiday, offering a small cushion for filing.

Disaster Area Extensions:
Taxpayers in disaster-designated areas may receive extended deadlines. For updates, consult FEMA's disaster declarations at https://www.fema.gov/disaster/declarations and the IRS's disaster relief information at https://www.irs.gov/newsroom/tax-relief-in-disaster-situations.

At MJ Ahmed CPA PLLC, we leverage over 25 years of expertise to guide you through these crucial deadlines, ensuring you achieve compliance and peace of mind.

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