Key Individual Tax Deadlines for September 2026
As we head into the fall season, it is a great time to review your 2026 tax situation and begin planning for 2027. With a key estimated tax payment due this month, now is an excellent opportunity to evaluate your income, withholdings, and prepayments to see if adjustments are needed before year-end. The team at Robertson Financial Group here in Tucker, Georgia, is ready to help you navigate these dates proactively. Contact our office to schedule a tax planning consultation.
September 10: Tip Reporting Deadline
If you are an employee who works for tips and you received more than $20 in tips during the month of August, you must report them to your employer no later than September 10. You can do this using IRS Form 4070 or by providing your own signed statement. This statement must include your name, address, and Social Security number, your employer’s name and address (or the establishment's name), the specific month or period the report covers, and the total tips received during that timeframe.
Once reported, your employer is required to withhold FICA taxes and income tax from your regular wages to cover those tips. If your regular paycheck is not sufficient to cover the required FICA and tax withholdings, your employer will report the uncollected amount in box 8 of your W-2 for the year. You will then be required to pay that uncollected withholding when you file your annual tax return.
September 15: Third Quarter Estimated Tax Payment
The third installment of your 2026 individual estimated taxes is due on September 15. Our federal tax system relies on a “pay-as-you-earn” structure. To help taxpayers meet this requirement, the government utilizes several collection methods, including:
- Payroll withholding for employees
- Pension withholding for retirees
- Estimated tax payments for self-employed individuals and those with other income sources not covered by traditional withholding
Underpayment Penalties and Safe Harbors
When a taxpayer fails to prepay a minimum required amount—known as a safe harbor—they can face an underpayment penalty. This penalty is calculated quarter-by-quarter and is equal to the federal short-term rate plus 3 percentage points.
Fortunately, federal tax law provides methods to avoid this underpayment penalty. First, no penalty is assessed if the underpayment is less than $1,000, which is known as the de minimis amount. Additionally, the law offers two primary "safe harbor" prepayment exceptions:
- Current Year Safe Harbor: If your payments equal or exceed 90% of the tax owed in the current year, you avoid the penalty.
- Prior Year Safe Harbor: If you pay 100% of your prior year’s tax liability, you avoid the penalty. However, for taxpayers whose Adjusted Gross Income (AGI) exceeds $150,000 (or $75,000 for married taxpayers filing separately), this prior year safe harbor requirement increases to 110%.
Safe Harbor Calculation Example
Suppose your total tax for the year is $10,000 and your prepayments amount to $5,600. This leaves you owing an additional $4,400 on your tax return. To determine if you owe a penalty, check the first safe harbor exception. Since 90% of $10,000 is $9,000, your $5,600 prepayment falls short, meaning you cannot avoid the penalty under this specific exception.
However, the second safe harbor may still protect you. Assume your prior year’s tax liability was $5,000. Because your $5,600 prepayment is greater than 110% of that prior year’s tax ($5,500), you successfully qualify for this safe harbor and escape the penalty entirely.
This example highlights the importance of ensuring your prepayments are adequate, particularly if you experience a substantial increase in income. Income spikes are common when a taxpayer retires, receives a large bonus, or realizes significant gains from the sale of stocks or property. Meeting the safe harbor exception also requires the timely payment of each estimated tax installment. If you have questions regarding your specific safe harbor estimates, please call Robertson Financial Group as soon as possible.
State Rules Caution
Please keep in mind that some state de minimis amounts, safe harbor estimate rules, and estimated payment due dates differ from federal regulations. Call our office to confirm the particular safe harbor rules for your state.
Weekends and Holidays
If a tax due date falls on a Saturday, Sunday, or a legal holiday, the deadline is automatically extended to the next business day that is not itself a legal holiday.
Disaster Area Extensions
When a specific geographical location is designated as a disaster area, tax due dates are typically extended. To find out if an area has been designated as a disaster area and to review the updated filing extension dates, visit the following resources:
- FEMA: https://www.fema.gov/disaster/declarations
- IRS: https://www.irs.gov/newsroom/tax-relief-in-disaster-situations
Taking Control of Your Fall Tax Planning
Staying on top of your September due dates is a highly effective way to keep your finances organized as we approach the end of the year. Whether you need to adjust your estimated payments or evaluate the tax impact of a recent income change, Michael Robertson and our team are here to provide clear, optimistic guidance. Contact Robertson Financial Group today to schedule your comprehensive tax planning consultation.
Sign up for our newsletter.
Each month, we will send you a roundup of our latest blog content covering the tax and business tips & insights you need to know.
We care about the protection of your data.