Essential Tax Deadlines for September 2025

As September 2025 approaches, crucial tax deadlines include reporting tips and making estimated tax payments. Master the safe harbor rules and learn how to steer clear of penalties, while also strategizing for 2026.

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September 10 - Tip Reporting Deadline

If you are an employee earning tips and accumulate more than $20 in tips during August, you must report them to your employer using IRS Form 4070 by September 10. Employers are responsible for withholding FICA and income taxes from your regular wages to cover these tips. Should your regular wages fall short, any uncollected withholding will be reported in box 8 of your W-2, and you will settle this when filing your annual tax return.

September 15 - Deadline for Estimated Tax Payments

The third installment of 2025 individual estimated taxes is due. In line with the "pay-as-you-earn" system, the government facilitates ongoing tax payments through several methods, including:

  • Payroll withholding for employees;

  • Pension withholding for retirees; and

  • Estimated tax payments for self-employed individuals and those earning other untaxed incomes.

Failure to meet the minimum (safe harbor) prepayments may incur underpayment penalties, equating to the federal short-term rate plus 3%, calculated quarterly. Federal law offers routes to avoid this by meeting "safe harbor" prepayments:

  • First, paying at least 90% of the current year's taxes exempts you from penalties.

  • Second, cover 100% of last year’s tax liability, increasing to 110% if your AGI exceeds $150,000 ($75,000 if married filing separately).

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Consider this scenario: Your tax debt for the year is $10,000, while prepayments total $5,600. You owe an additional $4,400. To avoid penalties, check if safe harbor conditions are met. Although your prepayments fall short of 90% ($9,000), assume last year's tax was $5,000; since you prepaid $5,600, surpassing the 110% safe harbor threshold (110% = $5,500), you avoid penalties.

This case highlights the necessity of maintaining adequate prepayments, especially when income fluctuates significantly due to capital gains, substantial bonuses, or retirement. Payments must be timely each quarter to utilize this safe harbor rule effectively. If you have queries concerning safe harbor estimates, contact our office without delay.

Important Reminder: Some states vary in their de minimis amounts and safe harbor criteria compared to federal standards. Contact us for state-specific guidance.

Weekend and Holiday Adjustments:

If a deadline lands on a weekend or legal holiday, it extends to the next non-holiday business day.

Extensions Due to Disasters:

Government-designated disaster areas receive filing extensions. For details on disaster area designations and extended filing dates, visit these links:

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

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