Q3 2026 Estimated Tax — September 15
Tuesday, September 15, 2026
Third quarter 2026 estimated tax payment due September 15 — covering June 1 through August 31 income.
Who must file or pay
Self-employed individuals, freelancers, S-Corp shareholders, and anyone expecting to owe $1,000+ in federal tax after withholding.
What you need to know
The Q3 2026 estimated tax payment covers income earned June 1 through August 31, 2026. This is the longest quarter (three full months) and often when self-employed income peaks for service businesses.
Q3 falls between the June and October deadlines, making it easy to overlook if you're focused on the October extension deadline. Set a calendar reminder in mid-August to review your income-to-date and calculate a proper payment.
If you are also extending your 2025 return (due October 15), remember that the extension deadline and the Q3 payment are separate events. Missing Q3 does not affect your extension, but it will generate an underpayment penalty regardless of when your 2025 return is ultimately filed.
Underpayment penalty under IRC §6654. If you file an extension for your 2026 return, you still must make this payment on time — extensions extend time to FILE, not time to PAY.
Required forms
- →Form 1040-ES
- →EFTPS (online payment)
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Other dates to know
Q1 2026 Estimated Tax — April 15
First quarter 2026 estimated tax payment due April 15 — covering January 1 through March 31 income.
Q2 2026 Estimated Tax — June 16
Second quarter 2026 estimated tax payment due June 16 — covering April 1 through May 31 income.
Q4 2026 Estimated Tax — January 15, 2027
Fourth and final quarter 2026 estimated tax payment due January 15, 2027 — covering September 1 through December 31.