If you are self-employed, own a business, earn investment income, or receive income that is not subject to enough tax withholding, estimated tax payments may be part of your annual tax responsibilities.
For the 2026 tax year, the third federal estimated tax payment (Q3) is due September 15, 2026.
With the September 15 deadline just around the corner, taxpayers and business owners should take time to review their income, payments already made, and expected tax liability for the remainder of the year. The September payment can also serve as an important checkpoint for identifying potential tax issues before year-end.
What Are Estimated Tax Payments?
The U.S. tax system generally operates on a pay-as-you-go basis. Employees typically have federal income taxes withheld from each paycheck. However, individuals who receive income without sufficient withholding may need to make estimated tax payments throughout the year.
This commonly applies to:
- Self-employed individuals
- Independent contractors
- Business owners
- Partners
- S corporation shareholders
- Individuals with significant investment, rental, interest, dividend, or capital gains income
Estimated payments generally cover income tax as well as other applicable taxes, such as self-employment tax.
When Are Estimated Taxes Due in 2026?
For individuals following the calendar tax year, estimated tax payments are generally divided into four payment periods.
The 2026 federal estimated tax deadlines are:
- Q1: April 15, 2026
- Q2: June 15, 2026
- Q3: September 15, 2026
- Q4: January 15, 2027
It is important to remember that the payment periods are not divided into equal three-month quarters. That is why the second estimated payment is due in June and the third in September.
How Do I Know How Much to Pay?
Estimated tax payments should be based on your expected income, deductions, credits, and taxes for the year.
For business owners, this calculation can become more complicated because income may fluctuate throughout the year. A strong first half of the year, a major new contract, investment gains, or changes in business expenses could all affect how much tax you ultimately owe.
This is one reason September is a valuable time to review your tax position.
Rather than automatically paying the same amount as earlier in the year, consider whether your financial situation has materially changed.
What Happens If I Miss the September 15 Deadline?
If you do not pay enough tax throughout the year, you could potentially face an underpayment penalty, even if you ultimately pay your entire tax bill when you file your return.
The amount of any penalty depends on factors including how much you underpaid and how long the amount remained unpaid.
If you missed an earlier estimated tax payment or believe you have underpaid, do not wait until tax season to address it. Your CPA can review your situation and help determine the appropriate next steps.
Why Q3 Is an Important Tax Planning Checkpoint
By September, you have several months of actual financial information available for the year. That can provide a much clearer picture than projections made in January.
For business owners, this is a good time to review year-to-date revenue, expenses, payroll, major purchases, retirement contributions, and anticipated income through December.
Your CPA can then evaluate whether estimated payments need to be adjusted and identify tax planning opportunities that may still be available before December 31.
Tax planning is generally more effective when there is time to act.
Q3 Estimated Taxes: Frequently Asked Questions
When is the Q3 estimated tax deadline in 2026?
The third federal estimated tax payment for the 2026 tax year is due September 15, 2026.
Who needs to make estimated tax payments?
Estimated taxes commonly apply to people who receive income without sufficient tax withholding, including business owners, self-employed individuals, independent contractors, and individuals with significant investment, rental, interest, dividend, or capital gains income.
Can I change my estimated tax payment during the year?
Yes. If your income or tax situation changes, your estimated payments may need to change as well.
What if my business made more money than expected?
Higher-than-expected income could increase your tax liability. Consider speaking with your CPA before making your next estimated payment.
Can DDC help calculate estimated tax payments?
Yes. DeMera DeMera Cameron works with individuals and businesses to evaluate tax obligations and develop proactive tax planning strategies.
With the September 15 deadline approaching, now is a good time to review your 2026 tax position. Contact DDC to evaluate your estimated tax payments and identify potential tax planning opportunities before year-end.