Blog

We keep you up to date on the latest tax changes and news in the industry.

Key Tax Deadlines for September 2025

Stay ahead this September 2025 with crucial tax deadlines on your radar, ensuring your tip reporting and estimated tax payments are timely. Dive into safe harbor rules, avert penalties, and streamline your strategies to prep for the 2026 tax season.

2025 Fall & 2026 Tax Planning

Secure a smooth tax season by connecting with our office to schedule a comprehensive planning session.

Image 2
September 10 - Tips Reporting Deadline

Employees who received over $20 in tips during August need to report their earnings to their employers using IRS Form 4070 by September 10. Employers have a legal obligation to withhold FICA and income taxes from these reported tips. If regular wages don't cover these withholdings, the employer will list the uncaptured amount in box 8 of your W-2. It's imperative that you pay these outstanding withholdings upon filing your annual return.

Image 3
September 15 - Estimated Tax Payment Due

The third installment of 2025 individual estimated taxes is due. Our tax system functions on a “pay-as-you-earn” principle, facilitated through methods including:

  • Payroll withholding for employees;

  • Pension withholding for retirees; and 

  • Estimated tax payments for the self-employed or those with non-withholding incomes.

Failing to meet the minimum safe harbor prepayment can trigger an underpayment penalty, calculated at the federal short-term rate plus 3 percentage points, assessed quarterly.

Federal guidelines offer pathways to sidestep this penalty. No penalty applies if the underpayment is below $1,000 (de minimis amount). Additionally, "safe harbor" prepayments are detailed here:

  • The initial safe harbor hinges on the current year’s tax liability, demanding prepayments that cover at least 90% of owed tax.

  • The second is based on prior year tax, normally 100% of the previous year’s tax liability. For those with AGIs over $150,000 ($75,000 for separate filers), this rises to 110%.

Example: With a tax liability of $10,000 and prepayments of $5,600, you owe $4,400. The first safe harbor isn't met as 90% of $10,000 is $9,000. Yet, given last year’s tax was $5,000, your $5,600 prepayment qualifies under the 110% safe harbor rule, avoiding penalties.

This scenario highlights the necessity of appropriate prepayment, especially amid significant income increases. Situations like stock or property sales, bonus payments, or retirement illustrate this. Ensure each estimated tax payment installment is timely to affirm safe harbor compliance and avoid penalties. Consult our office for precise guidance on your safe harbor estimates.

CAUTION: State-specific de minimis and safe harbor rules may differ from federal guidelines. Reach out to us for tailored state-specific advice.

Weekends & Holidays:

Due dates landing on weekends or public holidays automatically roll over to the next business day.

Disaster Area Extensions:
Recognized disaster zones offer extended deadlines. For current disaster declarations and specific extensions, visit:

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

Share this article...

Sign up for our newsletter.

Each month, we will send you a roundup of our latest blog content covering the tax and accounting tips & insights you need to know.

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 .

We care about the protection of your data.