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Key September 2025 Tax Deadlines & Planning Strategies

As we approach September 2025, it's crucial for individuals to be aware of significant tax deadlines including tip reporting and estimated tax payments. This guide delves into safe harbor rules, strategies to avoid penalties, and essential tips for preparing for 2026's tax requirements.

2025 Fall and Upcoming Year Tax Strategies

To navigate these pivotal times, reach out to our office to schedule a comprehensive tax planning consultation.

September 10 – Tip Reporting Obligation

Employees who earned over $20 in tips during August must report these to their employers by September 10 using IRS Form 4070. Employers are obligated to withhold FICA and income taxes on these tips. If your regular wages don’t cover the necessary withholding, your employer will note any uncollected amount in box 8 of your W-2, requiring you to settle these when you file your year-end tax return.

September 15 – Estimated Tax Payment Deadline

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The third installment for your 2025 individual estimated taxes is due. Our tax system depends on the "pay-as-you-earn" principle, supported by methods such as:

  • Payroll withholding for employed individuals;
  • Pension withholding for retirees;
  • Estimated tax payment for self-employed individuals and income sources without withholding.

If you haven’t prepaid a safe harbor threshold, you might face an underpayment penalty—computed using the federal short-term rate plus 3%. This penalty is assessed quarterly.

Federal law provides avenues to avoid the penalty. If your underpayment is under $1,000, no penalty applies. "Safe harbor" prepayments include:

  • Current-year tax equal to or exceeding 90%.
  • Previous-year tax equating to 100% (110% for AGI over $150,000, or $75,000 for married filing separately).

Example: Assume your annual tax is $10,000, and you've prepaid $5,600. With $4,400 owing, the safe harbor check shows a shortfall under the 90% rule. Yet, your prior year's $5,000 tax makes $5,600 prepayments eligible under the 110% rule, exempting you from penalties.

These calculations highlight prepayment importance, especially when income spikes from asset sales, significant bonuses, or retirement. Timely installment payments also ensure safe harbor penalty protection. For assistance with your prepayments, contact our office immediately.

Important Consideration: State-specific safe harbor and de minimis amounts may differ from federal rules. Contact our office for advice on your state’s regulations.

Handling Weekends and Holidays

If a deadline coincides with a weekend or legal holiday, it’s extended to the next business day that isn’t a holiday.

Extensions for Disaster Areas

Tax deadlines extend for regions designated as disaster areas. For current designated areas and deadlines, refer to the following:

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

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