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Key September 2025 Tax Deadlines and Planning Tips

As we approach September 2025, it's crucial to stay informed about important tax deadlines, particularly for tip reporting and estimated tax payments. Understanding safe harbor rules can help you avoid penalties and strategically prepare for the upcoming tax year. At Martinez & Shanken PLLC, located in Gilbert, AZ, we specialize in small business accounting and tax services. Let’s explore the essential deadlines and planning strategies you need to be aware of.

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2025 Fall and 2026 Tax Planning
It's always a wise move to get ahead with your tax planning. Contact us to schedule a consultation and tailor a strategy specifically for your financial situation.

September 10 - Report Tips to Employer
If you are earning tips and receive more than $20 during August, it's mandatory to report these to your employer using IRS Form 4070 by September 10. Your employer will then withhold FICA taxes and income tax from your regular wages. If there are insufficient wages, any uncollected amount will be noted in box 8 of your W-2 form for that year, and you'll need to settle the owed taxes when filing your return.

September 15 - Estimated Tax Payment Due
The third installment for 2025 individual estimated taxes must be submitted by this date. Our taxpayer system, functioning on a “pay-as-you-earn” basis, offers several options to meet such obligations, including:

  • Payroll withholding for employees;

  • Pension withholding for retirees; and

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

Penalties apply if you're under the required safe harbor amount. This penalty involves the federal short-term rate plus three percentage points, calculated quarterly. Federal law provides two safe harbors to avoid penalties:

  • Current Year Safe Harbor: Pay at least 90% of the current year's owed tax.

  • Previous Year Safe Harbor: Generally 100% of last year's tax liability, but 110% for those with an AGI over $150,000 ($75,000 for married filing separately).

Here's an example: If your tax liability is $10,000, with $5,600 in prepayments, you fall short of the 90% rule and face a penalty. However, if last year’s tax was $5,000 and you prepaid $5,600, you meet the 110% safe harbor and avoid the penalty.

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State and Federal Variances: Remember, state rules may differ. Always verify with us regarding your state's specific safe harbor requirements.

Weekend, Holiday, and Disaster Extensions:
Deadlines falling on weekends or holidays extend to the next business day. Disaster areas also qualify for extensions. Check FEMA and IRS resources for updates on affected regions:
FEMA
IRS

By understanding these deadlines and planning accordingly, you can ensure compliance and minimize stress during tax season. Reach out to our office for personalized assistance and expert advice tailored to your specific needs.

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Martinez & Shanken, PLLC

1560 W Warner Rd Suite 200
Gilbert, Arizona 85233
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