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Key Tax Deadlines for September 2025

As we navigate through September, it's time for businesses to gear up for crucial tax deadlines. This month, we spotlight important dates for S corporations, partnerships, corporate estimated payments, and payroll tax deposits, all closely clustered around September 15th. Staying aware of these deadlines is fundamental for maintaining compliance and strategic financial planning, something we at Desert Lily Bookkeeping emphasize for our clients.

September 15 - S Corporations
September 15 is pivotal for S corporations operating on a calendar year that filed for an automatic 6-month extension. You must file your 2024 income tax return (Form 1120-S) and settle any tax obligations by this date. Additionally, each shareholder must receive a copy of their Schedule K-1 (or substitute Schedule K-1), and, where applicable, a Schedule K-3 (or substitute Schedule K-3).

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September 15 - Corporations
For corporations following a calendar fiscal year, this date also marks the deadline for making the third installment of estimated income tax payments for 2025. With accurate and organized financial statements, handled expertly via our services, forecasting and meeting these obligations become seamless.

September 15 - Partnerships
Partnerships that secured a 6-month extension must file their 2024 return (Form 1065) by September 15. Distributing a copy of Schedule K-1 to each partner and, if needed, a Schedule K-3, is also required. Ensuring precision and timeliness in these filings aids in sustaining fruitful partnerships.

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September 15 - Social Security, Medicare, and Withheld Income Tax
Employers, if you're adhering to monthly deposit rules, September 15 is crucial for depositing Social Security, Medicare, and withheld income taxes for August. This due date also applies to nonpayroll withholding deposits.

Accounting for Weekends & Holidays
If a due date lands on a weekend or legal holiday, it automatically extends to the next business day that's not a holiday. This small relief can be pivotal for last-minute preparations.

Relief for Disaster Areas
Businesses located in areas designated as disaster zones might enjoy extended deadlines. Staying informed through FEMA and the IRS ensures you're up-to-date on any changes affecting your obligations.

At Desert Lily Bookkeeping, we guide service-based businesses through these intricate deadlines, lifting the burden off your shoulders with our reliable and forward-thinking financial solutions. Let us handle the details so you can focus on building and thriving in your enterprise.

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Book Your Free Consultation
Book your free consultation with me today to see how we can get you back on track.
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