Key Tax Deadlines for September 2025: Essential Planning

September 2025 presents crucial tax deadlines for individuals, including tip reporting and the timely payment of estimated taxes. Gain insights into safe harbor rules to expertly navigate these requirements, minimize penalties, and strategically prepare for 2026’s tax obligations.

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September 10 - Tip Reporting to Employers
If you’re an employee earning tips, any amount over $20 received in August must be reported to your employer using IRS Form 4070 by September 10. Employers must withhold FICA and income taxes from your regular wages for these tips. If regular wages don’t cover the tax withholding, the uncollected amount appears in box 8 of your W-2, payable at your tax return filing.

September 15 - Third Estimated Tax Payment

The third installment for 2025's individual estimated taxes is due. Our tax system functions on a “pay-as-you-earn” basis, supported by payroll withholding for employees, pension withholding for retirees, and estimated tax payments for self-employed individuals and those with taxable income not subject to withholding.

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Failure to prepay a safe harbor minimum can result in penalties, calculated quarterly at the federal short-term rate plus 3%. Avoid penalties with payments less than $1,000, or by meeting safe harbor prepayments:

  • If current year payments are at least 90% of your total liability, you avoid penalties.
  • Pay 100% of the prior year’s tax liability, or 110% for AGI over $150,000, to meet the second safe harbor.

Illustration: Consider having a tax liability of $10,000 with prepayments totaling $5,600. You owe $4,400. The first safe harbor requires 90% ($9,000), meaning you cannot avoid penalties under this rule. However, if last year’s tax was $5,000 and current prepayments exceed 110% ($5,500), you escape the penalty.

This underscores the significance of adequate prepayments, especially with income surges from stock sales, bonuses, or retirement. Ensuring timely payment of each installment is crucial to meet safe harbor criteria. Contact us promptly for guidance on your safe harbor estimates.

Caution: State de minimis amounts and safe harbor rules may differ from federal standards. Reach out for specifics regarding your state’s requirements.

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Extended Deadlines for Weekends & Holidays
If a due date falls on a weekend or legal holiday, it is extended to the next business day.

Disaster Area Deadlines
Areas declared disaster zones receive extended deadlines. For up-to-date disaster declarations and extensions, visit FEMA and IRS.

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