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September 2025 Tax Deadlines and Safe Harbor Strategies

September 2025 ushers in essential tax deadlines crucial for compliance and future tax planning. These deadlines, including tip reporting and estimated tax payments, are vital for maintaining safe harbor rules, avoiding penalties, and strategizing for the 2026 tax year.

2025 Fall and 2026 Tax Planning

Now is a perfect time to consult with Ember Coaching & Financial Services to optimize your tax strategy and prepare for the upcoming year. Contact our office to schedule a consultation.

September 10 - Report Tips to Employer

If you're an employee earning tips exceeding $20 in August, you must report them to your employer using IRS Form 4070 by September 10. Your employer will withhold FICA taxes and income tax from these tips. Should your wages be insufficient to cover these withholdings, the uncollected amounts will appear in box 8 of your W-2, necessitating payment upon filing your tax return.

September 15 - Estimated Tax Payment Due

The third installment for 2025 individual estimated taxes is due. Our “pay-as-you-earn” system provides mechanisms like:

  • Payroll withholding for employees;

  • Pension withholding for retirees; and 

  • Estimated tax payments for self-employed individuals and income not subject to withholding.

Failure to prepay a safe harbor (minimum) amount results in an underpayment penalty, calculated as the federal short-term rate plus 3 percentage points on a quarter-by-quarter basis.

Avoid penalties under federal tax law through two safe harbors:

Safe Harbor 1: Ensure payments equal or exceed 90% of the current year's tax. Failure to achieve this may trigger penalties.
Safe Harbor 2: Cover 100% of the previous year’s tax liability (110% if your AGI is over $150,000 or $75,000 for married separately).

Example: If your tax for the year is $10,000 with $5,600 in prepayments, you owe $4,400. Check if you qualify for the first safe harbor. Here, 90% of $10,000 is $9,000, so prepayments are insufficient under this safe harbor. However, if last year’s tax was $5,000 and prepayments are $5,600, you surpass 110% of the prior year's taxes, qualifying for the second safe harbor.

Adequate prepayment is crucial, especially if your income surges due to stock sales, property sales, bonuses, or retirement. Timely estimated tax installments are essential to meet safe harbor criteria. For inquiries on your safe harbor estimates, don't hesitate to contact our office.

CAUTION: State-specific de minimis amounts and safe harbor rules may differ. Please consult us for state-specific regulations.

Weekends & Holidays:

If a due date coincides with weekends or holidays, deadlines extend to the next business day not considered a holiday.

Disaster Area Extensions:
In disaster-designated areas, deadlines are extended. Confirm disaster designation and extension details via the following resources:

FEMA: FEMA Disaster Declarations
IRS: IRS Tax Relief in Disaster Situations

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