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Critical September 2025 Tax Deadlines: Essential Tips for Compliance

As we navigate the intricate landscape of tax responsibilities, September 2025 presents several key deadlines for taxpayers. This month includes crucial dates for tip reporting and estimated tax payments, making it vital to stay informed and prepared. The team at Thompson-Smith CPA, LLC, led by Florida-licensed CPA Georgia Smith, stands ready to offer expert guidance with a personal touch throughout this process.

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September 10 - Report Tips to Employer

If you’re an employee receiving tips greater than $20 during August, you're required to report these to your employer using IRS Form 4070 by September 10. Your employer will withhold FICA taxes and income tax from your regular wages. If regular wages don't cover the withholding, any uncollected amount will be detailed in box 8 of your W-2, requiring settlement upon filing your return.

September 15 - Estimated Tax Payment Due

The third installment of individual estimated taxes for 2025 is due. The U.S. tax system operates on a “pay-as-you-earn” basis, offering several methods to fulfill this obligation:

  • Payroll withholding for employees;

  • Pension withholding for retirees; and

  • Estimated tax payments for the self-employed and others with non-withholding income sources.

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Failing to meet a safe harbor minimum could result in underpayment penalties calculated quarterly as the federal short-term rate plus three percentage points. However, the law provides relief through safe harbor provisions:

  • The first is based on your current year’s tax liability, where prepayments must meet or exceed 90% of the annual tax owed.

  • The second is based on the prior year’s liability, generally requiring 100% of the previous year’s tax, or 110% for higher income levels (AGI over $150,000 or $75,000 if married filing separately).

Example: Imagine your tax for the year amounts to $10,000 with prepayments totaling $5,600, leaving a $4,400 balance due. Under the first safe harbor (90% of $10,000 is $9,000), penalties apply; however, if the prior year’s tax was $5,000, and you prepaid $5,600, meeting 110% of the prior year’s liability ($5,500), you would avoid penalties under the second safe harbor.

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It’s critical to ensure prepayments are accurate, especially amidst significant income fluctuations, such as asset sales or retirement. Timely installment payments are also necessary to meet safe harbor criteria. Thompson-Smith CPA, LLC is available to assist in refining your safe harbor estimates.

CAUTION: State-specific de minimis amounts and safe harbor criteria may differ from federal standards. Contact us for state-specific guidance.

Weekends & Holidays:

Due dates falling on weekends or national holidays are extended to the following business day.

Disaster Area Extensions: Geographically declared disaster areas receive extended filing deadlines. For current disaster designations, visit:

FEMA: https://www.fema.gov/disaster/declarations
IRS: https://www.irs.gov/newsroom/tax-relief-in-disaster-situations

Ensure compliance with these critical deadlines and optimize your tax planning strategies by consulting our dedicated team promptly.

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