Key September 2025 Tax Deadlines for Individuals

As we approach September 2025, it's essential to be mindful of important tax deadlines, notably tip reporting and estimated tax payments. Understanding the safe harbor rules can help prevent penalties and position you well for strategic tax planning into 2026.

September 2025 Tax Planning: Preparing for a Successful Year-End

Contact Melvin P. Crilley, EA Inc. for tailored tax planning assistance to make the most of your financial strategies.

September 10 - Tip Reporting

Employees who earn tips must report any amount over $20 for August to their employers by September 10 using IRS Form 4070. Employers will then facilitate withholding for FICA and income tax from regular wages. If your wages are insufficient, the uncollected amount will appear in box 8 of your W-2, and you’ll need to reconcile it when filing your tax return.

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September 15 - Estimated Tax Payment Due

The "pay-as-you-earn" tax system requires the third installment of your 2025 individual estimated taxes by September 15. There are different mechanisms to help you comply, including:

  • Payroll withholding for employees;

  • Pension withholding for retirees;

  • Estimated tax payments for other income sources.

Failing to meet prepayment safe harbors may lead to underpayment penalties calculated at the federal short-term rate plus 3% per quarter.

Federal law outlines manageable ways to avoid penalties, including safe harbor provisions:

  • Prepaying at least 90% of current year tax;

  • Meeting prior year tax liability requirements, which for AGI over $150,000 ($75,000 if married separately) are pegged at 110%.

For example, if your total 2025 tax is $10,000, prepayments should hit $9,000 (90%) to avoid penalties. However, using the previous year's tax figure might offer another safe harbor if prepayments exceed the required percentage for prior year taxes.

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It’s vital to ensure your prepayments keep pace with increased earnings due to events like asset sales or bonuses. Consistent estimated tax payments per quarter are necessary to adhere to safe harbor rules. For personalized guidance, reach out to us as soon as possible.

State and Federal Differences and Extensions

Note some states have different safe harbor guidelines. Consult us to navigate state-specific nuances.

If your due date aligns with a weekend or holiday, it extensions to the following business day apply automatically. Additionally, disaster-affected areas benefit from filing extensions. For up-to-date information, visit FEMA or IRS.

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