As summer comes to an end, an important tax deadline is approaching. The third-quarter estimated tax payment deadline for 2026 is September 15, 2026.
If you make estimated tax payments, now is a good time to review your income, withholding, and any significant financial changes that have occurred during the year. In some cases, the amount originally projected earlier in the year may need to be adjusted.
Who Needs to Make Estimated Tax Payments?
Estimated tax payments are generally used to pay taxes on income that is not subject to sufficient withholding. This may include:
- Self-employment or business income
- Interest and dividends
- Capital gains from the sale of investments
- Rental income
- Bonuses or other compensation
- Other sources of taxable income without adequate withholding
Generally, individuals may need to make estimated payments if they expect to owe at least $1,000 in federal tax after accounting for withholding and refundable credits.
Has Your Income Changed Since Your Estimates Were Calculated?
Estimated payments are based on the information available at the time they are calculated. However, your financial situation can change throughout the year.
Before making your September payment, consider whether you have experienced any significant changes, such as:
- A substantial increase or decrease in income
- A large bonus or commission
- The vesting or sale of company stock or RSUs
- Significant capital gains or losses
- A major investment sale
- New self-employment or business income
- Changes in retirement plan contributions
- A change in your job or withholding
- Significant changes in deductions or credits
If your financial situation has changed significantly, updating your tax projection can help determine whether your previously calculated estimated payment is still appropriate.
Why Estimated Payments Matter
The federal income tax system is generally a pay-as-you-go system. Taxes are expected to be paid throughout the year through withholding, estimated tax payments, or a combination of both.
Paying too little during the year can result in an underpayment penalty, even if the remaining tax is ultimately paid when the return is filed.
Generally, taxpayers can avoid an estimated tax underpayment penalty by paying enough through withholding and estimated payments to satisfy applicable safe-harbor rules. For many taxpayers, this means paying at least 90% of the current year’s tax liability or 100% of the prior year’s tax liability, whichever is less.
Different rules apply to certain higher-income taxpayers. For taxpayers whose prior-year adjusted gross income exceeded $150,000 ($75,000 if married filing separately), the prior-year safe-harbor percentage generally increases from 100% to 110%.
Don’t Automatically Assume Last Quarter’s Amount Is Still Correct
Estimated payments do not always remain the same throughout the year.
For example, someone who sold a significant investment during the summer may have considerably more taxable income than originally anticipated. On the other hand, a taxpayer whose income decreased or who increased retirement contributions may have a different projected tax liability.
This is why tax planning throughout the year can be valuable. Reviewing your tax situation before a quarterly deadline provides an opportunity to make adjustments rather than discovering a large difference when preparing your return.
September 15 Is Approaching
The third-quarter 2026 estimated tax payment is due September 15, 2026.
If your income and financial circumstances have remained consistent with the information used to prepare your original tax projection, your previously calculated estimated payment may still be appropriate.
If you’ve experienced a significant change, however, consider reviewing your tax situation before making the payment.
David Miller CPA LLC can assist with tax projections and estimated tax planning to help determine whether adjustments may be appropriate based on your individual circumstances.
This article is for general informational purposes only and should not be considered tax, legal, or financial advice. Tax situations vary by individual. Consult a qualified tax professional regarding your specific circumstances.