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Key Tax Deadlines for September 2025: Ensure Compliance and Avoid Penalties

The month of September brings pivotal tax deadlines that individuals must not overlook. It encompasses essential tax obligations such as reporting tips and making estimated tax payments. Understanding safe harbor provisions and planning ahead for 2026 can be instrumental in avoiding penalties and achieving a stress-free tax compliance experience.

Planning Your Tax Strategy for Fall 2025 and Beyond

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Contact our office to arrange a consultation and fine-tune your tax strategy for the upcoming year.

September 10 - Mandatory Tip Reporting

Employees receiving more than $20 in tips during August are required to report them to their employer using IRS Form 4070 by September 10. Employers must then withhold FICA and income taxes on these tips. When regular wages are insufficient to cover the withholdings, the uncollected amount is reflected in box 8 of the W-2 form, necessitating payment alongside your annual return.

September 15 - Third Installment of Estimated Taxes Due

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The third installment of 2025 estimated tax for individuals is due. Our tax regime operates on a 'pay-as-you-earn' system, offering various means for taxpayers to comply:

  • Employee payroll withholding

  • Retiree pension withholding

  • Estimated tax payments for self-employed and other non-withholding income sources

Failure to meet the minimum prepayment, or safe harbor amount, triggers an underpayment penalty. This penalty comprises the federal short-term rate plus 3 percentage points and is assessed quarterly.

The federal tax code provides relief from this penalty through two safe harbor prepayment methods:

  • Prepaying at least 90% of the current year's owed taxes can help you avoid penalties.

  • Making prepayments that are at least equal to 100% (or 110% for those with AGI over $150,000) of last year's tax liability also qualifies as a safe harbor.

Illustrative Example: If your tax liability is $10,000 with $5,600 prepaid, you owe $4,400 additionally. For penalty assessment, see if you meet the 90% threshold ($9,000). In this case, it's not met. However, should last year’s tax be $5,000, your prepayment of $5,600 satisfies the 110% rule, thus avoiding penalties.

This highlights the necessity of accurate prepayments, especially with increased income from events like significant stock sales, property sales, bonuses, or retirement. Timely estimated payments are crucial to meeting safe harbor standards and avoiding penalties. If you have any doubts or need recalculations of your estimates, reach out to our office immediately.

Note: States may have different de minimis amounts and safe harbor rules. Contact our office for specific state guidelines.

Weekend and Holiday Extensions: Any due date falling on a weekend or holiday extends to the next business day.

Extensions in Disaster Areas: Affected regions by disasters may receive filing extensions. Check the following for more information:

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

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