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Mark Your Calendar: September 2026 Individual Tax Deadlines

Fall is a great time to review your 2026 tax situation and get a head start on planning for 2027. With an estimated tax payment due this month, it is also the perfect opportunity to check your income, withholding, and estimated payments to see if any adjustments should be made before the year wraps up. Contact GeneralCents Accounting to schedule a tax planning consultation.

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September 10: Report Tips to Your Employer

If you are an employee who earns tips and you received more than $20 in tips during August, you are required to report them to your employer no later than September 10. You can use IRS Form 4070 or simply provide your own written statement. If you use your own statement, it must include your signature; your name, address, and Social Security number; your employer's name (or the establishment's name) and address; the month or period the report covers; and the total amount of tips you received during that time.

Your employer uses this report to withhold FICA and income taxes from your regular wages. If your regular wages aren't high enough to cover those taxes, the uncollected withholding will show up in box 8 of your W-2 for the year. You will then be required to pay that uncollected amount when you file your annual tax return.

September 15: Third Quarter Estimated Tax Payment Due

The third installment of your 2026 individual estimated taxes is due on September 15. The U.S. tax system operates on a "pay-as-you-earn" basis, meaning you're expected to pay taxes as you generate income throughout the year. The government provides several ways to help taxpayers meet this requirement, including:

  • Payroll withholding for employees;
  • Pension withholding for retirees; and
  • Estimated tax payments for self-employed individuals and those earning other income not covered by withholding.

If you fail to prepay a safe harbor (minimum) amount, you can be subject to an underpayment penalty. This penalty is equal to the federal short-term rate plus 3 percentage points, and the IRS calculates it on a quarter-by-quarter basis.

How to Avoid the Underpayment Penalty

Federal tax law provides specific ways to avoid the underpayment penalty. First, if your underpayment is less than $1,000 (the de minimis amount), no penalty is assessed. Beyond that, the law offers two "safe harbor" prepayments:

  • The Current Year Safe Harbor: If your payments equal or exceed 90% of what you owe for the current year, you escape the penalty.
  • The Prior Year Safe Harbor: Alternatively, you can avoid the penalty by paying 100% of your prior year's tax liability. However, if your Adjusted Gross Income (AGI) exceeds $150,000 (or $75,000 for married taxpayers filing separately), this safe harbor bumps up to 110% of the prior year's tax.

A Safe Harbor Example

Suppose your tax for the year is $10,000 and your prepayments total $5,600. The result is that you owe an additional $4,400 on your tax return. Do you owe a penalty? First, see if you meet the current year safe harbor exception. Since 90% of $10,000 is $9,000, your $5,600 prepayments fell short of the mark. You cannot avoid the penalty under this exception.

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However, the second safe harbor may still apply. Assume your prior year's tax was $5,000. Because you prepaid $5,600, which is greater than 110% of the prior year's tax (110% of $5,000 is $5,500), you qualify for this safe harbor and can escape the penalty.

This example underscores the importance of making sure your prepayments are adequate, especially if you experience a large increase in income. This is a common situation when there is a large gain from the sale of stocks or property, when large bonuses are paid, or when a taxpayer retires. Remember, timely payment of each required estimated tax installment is also necessary to meet the safe harbor exception. If you have questions regarding your safe harbor estimates, please call our office as soon as possible.

A Note on State Rules

CAUTION: Keep in mind that some state de minimis amounts, safe harbor estimate rules, and estimated payment due dates differ from the Federal guidelines. Whether you are in Scottsdale, Denver, Albuquerque, or elsewhere, please call us to check on your particular state's safe harbor rules.

Weekends and Holidays

If a tax due date happens to fall on a Saturday, Sunday, or legal holiday, the deadline is automatically extended until the next business day that is not itself a legal holiday.

Extensions for Disaster Areas

When a geographical area is officially designated as a disaster area, tax due dates will be extended. To find out if a specific area has been designated as a disaster area and to view the filing extension dates, you can visit the following websites:

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

Let's Plan for the Rest of the Year

Staying on top of your September due dates keeps you compliant and protects you from unnecessary penalties. As John Koloch and the team at GeneralCents Accounting always say, proactive planning paves the way for a smoother tax season.

If you need assistance reviewing your Q3 estimated payments, or want to discuss year-end tax strategies, reach out to schedule a consultation with your BackPocket CFO today.

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