The third quarter estimated tax deadline for 2026 is Tuesday, September 15. The date falls on a weekday, so no weekend or holiday extension applies. This installment covers income earned from June 1 through August 31 that wasn’t subject to withholding, and it’s the third of four payments the IRS expects from taxpayers who will owe at least $1,000 beyond what’s already withheld from paychecks or pensions.1Internal Revenue Service. Individuals 2
Who Owes a Payment on September 15
The federal system runs on pay-as-you-go. If you earn money without automatic withholding, the IRS expects installments across the year rather than a single payment at filing.2Internal Revenue Service. Estimated Taxes That pulls in freelancers, independent contractors, landlords, investors with meaningful capital gains or dividends, and anyone with self-employment income. W-2 employees get caught too when side income or investment gains push their total bill past the threshold.
The trigger: if you expect to owe $1,000 or more in federal income tax for 2026 after withholding and refundable credits, you generally need to make estimated payments.2Internal Revenue Service. Estimated Taxes Sole proprietors, partners, and S corporation shareholders are the groups the IRS flags most often.
One narrow exemption: you can skip estimated payments entirely if you had zero tax liability for the prior year, that year covered a full 12 months, and you were a U.S. citizen or resident the whole time.3Office of the Law Revision Counsel. 26 U.S. Code 6654 – Failure by Individual to Pay Estimated Income Tax
How Much to Send
Your payment total through September 15 needs to meet one of two safe harbors, whichever is smaller:
- 90% of your 2026 tax, or
- 100% of the total tax shown on your 2025 return, provided that return covered a full 12 months.
The prior-year number is already known, which makes it the easier target. The tradeoff: if your 2026 income drops, basing payments on last year’s higher tax means overpaying and waiting for a refund.4Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
Higher earners face a steeper bar. If your adjusted gross income on your 2025 return exceeded $150,000 (or $75,000 if you’re married filing separately in 2026), the prior-year safe harbor rises from 100% to 110%.3Office of the Law Revision Counsel. 26 U.S. Code 6654 – Failure by Individual to Pay Estimated Income Tax If your 2025 tax was $20,000 and your AGI cleared $150,000, you’d need at least $22,000 across the four installments to stay safe under this method.
Dividing by Four, or Using Annualized Income
The simplest approach: take your required annual payment, divide by four, and send that amount each quarter. This works when income arrives at a steady pace.
If your income is lumpy or seasonal, equal quarters can force you to overpay early in the year. The Annualized Income Installment Method lets you base each payment on income actually earned through the end of that period. For the third quarter, calculate tax on your income from January 1 through August 31, then subtract what you paid for the first and second quarters. The remainder is your September 15 payment.5Internal Revenue Service. 2025 Instructions for Form 2210 – Underpayment of Estimated Tax by Individuals, Estates, and Trusts It takes more recordkeeping but can lower what you need to send when income spikes later in the year.
Prior-Year Refunds and Mid-Year Changes
If you elected to apply your 2025 refund to 2026 estimated tax, the IRS credits that amount against your first installment, with any excess rolling forward to later quarters. You’ll report estimated payments on Form 1040, line 26, including the carried-forward overpayment.6Internal Revenue Service. Estimated Tax
If your income or filing status has shifted since the second quarter, rework the numbers using a fresh Form 1040-ES worksheet and adjust the September 15 payment accordingly.2Internal Revenue Service. Estimated Taxes If you overpaid earlier in the year, you can reduce this installment to compensate.
How to Pay by September 15
Several payment methods are available. The one you pick matters less than making sure the payment is submitted or postmarked by the deadline.
IRS Direct Pay
The simplest option for individuals. You pay directly from a checking or savings account through the IRS website or the IRS2Go app, with no fees and no pre-registration. You’ll get immediate confirmation.7Internal Revenue Service. Direct Pay with Bank Account Select “Estimated Tax” as the payment type and apply it to the 2026 tax year.
EFTPS
EFTPS has long been the standard for scheduling payments in advance, but the system is changing. The IRS stopped accepting new individual enrollments through EFTPS in October 2025, and individual taxpayers are expected to transition to Direct Pay or IRS Online Account by late 2026.8EFTPS. Welcome to EFTPS Online Already enrolled as an individual? You can still use it for the September payment. Business taxpayers aren’t affected by this change. Payments must be scheduled by 8 p.m. ET the day before the due date to count as timely.
Credit or Debit Card
You can pay with a credit card, debit card, or digital wallet through IRS-approved third-party processors. Credit card payments carry a fee of roughly 1.75% to 1.85% of the payment, and personal debit card payments cost a flat $2.10 to $2.15. None of the fee goes to the IRS.9Internal Revenue Service. Pay Your Taxes by Debit or Credit Card or Digital Wallet On a $5,000 payment, a 1.75% credit card fee adds $87.50. Worth knowing before you swipe for the points.
Mail With Form 1040-ES
You can still mail a check or money order with the Form 1040-ES voucher for the third quarter; the due date is printed in the upper-right corner. Make the check payable to “United States Treasury” and write your Social Security number and “2026 Form 1040-ES” on it. The correct mailing address depends on your state and is listed in the Form 1040-ES instructions.10Internal Revenue Service. Form 1040-ES – Estimated Tax for Individuals For mailed payments, the postmark controls whether you paid on time.
If You Miss September 15 or Pay Too Little
Missing the deadline or underpaying the installment triggers the underpayment penalty, which is essentially interest on the shortfall. The IRS calculates it separately for each quarter, running from the missed due date until the tax is paid or until the annual return due date, whichever comes first.4Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
The rate ties to the federal short-term rate plus three percentage points, resetting each calendar quarter. For the first quarter of 2026, the rate was 7% per year, compounded daily.11Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 It dropped to 6% for the second quarter starting April 1, 2026.12Internal Revenue Service. Internal Revenue Bulletin: 2026-08 The third quarter rate, which applies to the September 15 installment, is announced separately and can change again.
The penalty is calculated on Form 2210. The IRS will often figure it for you if you file your return without the form, but if you used the annualized income method or qualify for an exception, you’ll need to file Form 2210 yourself to claim the lower amount.5Internal Revenue Service. 2025 Instructions for Form 2210 – Underpayment of Estimated Tax by Individuals, Estates, and Trusts
Exceptions and Waivers
You won’t owe a penalty if your total tax after withholding and refundable credits is under $1,000.3Office of the Law Revision Counsel. 26 U.S. Code 6654 – Failure by Individual to Pay Estimated Income Tax Meeting either safe harbor also gives complete protection.
Beyond the automatic safe harbors, the IRS can waive the penalty in two situations. The first covers casualty, disaster, or other unusual circumstances where imposing the penalty would be inequitable. The second applies if you retired after reaching age 62 or became disabled during the tax year the payments were due (or the year before), and the underpayment was due to reasonable cause rather than willful neglect.3Office of the Law Revision Counsel. 26 U.S. Code 6654 – Failure by Individual to Pay Estimated Income Tax Neither waiver is automatic; file Form 2210 and check the appropriate box to request relief.
One group is outside the September 15 deadline entirely. If at least two-thirds of your gross income comes from farming or fishing, you can make a single estimated payment by January 15 of the following year, or skip estimated payments and file the return with full payment by March 1.13Internal Revenue Service. Farmers and Fishermen The quarterly schedule doesn’t apply to you.