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September 2025 Tax Deadlines: Key Insights for Individuals

As September 2025 approaches, staying informed about crucial tax deadlines is vital, particularly for the timely reporting of tips and estimated tax payments. This guide will help you grasp safe harbor rules, avoid penalties, and strategically plan for 2026's tax obligations.

2025 Fall and 2026 Tax Planning

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September 10 - Report Tips to Employer

If you earn tips, it's essential to report any amount exceeding $20 received in August to your employer by September 10 using IRS Form 4070. Your employer must withhold FICA taxes and income tax on these tips. If regular wages do not cover the necessary withholdings, the uncollected amount will be noted in box 8 of your W-2. You will need to settle this when filing your annual return.
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September 15 - Estimated Tax Payment Due

The third installment for individual estimated taxes for 2025 is due—and it's essential to adhere to our "pay-as-you-earn" tax system. Methods to support your compliance include:

  • Payroll withholding for employees,

  • Pension withholding for retirees, and,

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

Failing to prepay a safe harbor amount can trigger an underpayment penalty, calculated with the federal short-term rate plus 3 percentage points, applied quarterly. Fortunately, federal tax law provides exceptions to this penalty:

  • If underpayments are less than $1,000, no penalty applies.

  • Paying at least 90% of the current year's tax liability can also avoid penalties.

  • Last year's tax liability offers another safe harbor if you pay 100% of that amount (110% for higher-income taxpayers).

Example: Let's illustrate: if your tax liability for the year is $10,000 with prepayments of $5,600, you owe $4,400 at filing time. The 90% rule means you should have paid $9,000, and hence, may owe a penalty. However, if you owed $5,000 last year and paid $5,600 this year—exceeding the 110% threshold—you're covered by the safe harbor provision.Image 3

This example highlights the importance of accurate prepayment assessments, essential when experiencing significant income shifts or gains. If you're uncertain about your safe harbor obligations, our team is ready to guide you.

CAUTION: Be aware: State-specific safe harbor and de minimis rules may differ from federal guidelines. For tailored advice, connect with our office.

Weekends & Holidays:

If your due date falls on a weekend or public holiday, it automatically extends to the next business day.

Disaster Area Extensions:
Designated disaster areas may receive tax relief extensions. For details, check official sources:

By staying proactive with these deadlines and rules, you can avoid expensive penalties and prepare effectively for the year ahead.

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