How can we assist you? Book an appointment with us today!

Key Tax Deadlines and Strategies for September 2025

The month of September 2025 brings important tax deadlines for individuals, including mandatory tip reporting and estimated tax payments. Understanding safe harbor rules and how to avoid penalties can set the stage for a smoother tax season in 2026. Let's dive into these key dates and strategies for effective tax planning.

Strategic Tax Planning for Fall 2025 and Beyond

Contact our office to book a consultation and explore tailored tax strategies.

Image 1

September 10 - Employee Tip Reporting

If you are a tipped employee who received over $20 in tips during August, you must report these to your employer using IRS Form 4070 by September 10. Your employer will withhold FICA taxes and income tax from these tips alongside your regular wages. Should your wages be insufficient to cover the withholding amounts, your employer will report this in box 8 of your W-2. You are required to pay any uncollected withholding when you file your tax return.

Image 2

September 15 - Estimated Tax Payments

The third installment of 2025 estimated taxes for individuals is due. As part of the "pay-as-you-earn" system, taxpayers have multiple options to pay taxes throughout the year:

  • Payroll withholding for salaried employees;
  • Pension withholding for those in retirement;
  • Estimated payments for self-employed individuals and others with income streams not subject to withholding.

Failure to prepay a safe harbor amount can result in an underpayment penalty, calculated as the federal short-term rate plus 3 percentage points on a quarterly basis.

To avoid this penalty, ensure prepaid taxes meet either of the IRS-provided safe harbors:

  • The first safe harbor is 90% of the current year’s tax liability.
  • The second is 100% of the prior year’s tax, increasing to 110% for those with an AGI exceeding $150,000 ($75,000 for separate filers).
Image 3

Example: Assume your tax is $10,000, with prepayments totaling $5,600, leaving $4,400 owed. To check for penalties, the first safe harbor requires $9,000 in prepayments, but you've fallen short. However, if last year’s tax was $5,000 and prepayments are $5,600 (exceeding 110% of $5,500), you escape the penalty through the second safe harbor.

These examples highlight the importance of accurate prepayments, especially with income changes due to significant events, such as property sales or retirement. Timeliness in estimated payments is also critical to meeting safe harbor conditions.

Consult with Us: If you have concerns about your safe harbor estimates, please reach out to our office for assistance.

Important Considerations:

  • State guidelines for safe harbors and de minimis exemptions may differ. Please contact our office for specific state regulations.
  • If deadlines coincide with weekends or holidays, extensions apply to the next business day not classified as a holiday.
  • Disaster declarations can alter deadlines, so check FEMA and IRS sites for relevant updates:

Share this article...

Want tax & accounting tips and insights?

Sign up for our newsletter.

I confirm this is a service inquiry and not an advertising message or solicitation. By clicking “Submit”, I acknowledge and agree to the creation of an account and to the and .

Affiliations