For the 2026 tax year: April 15, June 15, September 15, and January 15, 2027. The underpayment penalty is calculated quarter by quarter, so a missed installment costs you even if you catch up later. Set one recurring reminder and the whole year is covered.
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Same dates whether you are a C-corporation filing Form 1120-W or an individual filing Form 1040-ES (which covers S-corp shareholders, partners, sole proprietors, and most LLC members).
| Quarter | Period covered | Due date |
| Q1 2026 | Jan 1 – Mar 31, 2026 | April 15, 2026 |
| Q2 2026 | Apr 1 – May 31, 2026 | June 15, 2026 |
| Q3 2026 | Jun 1 – Aug 31, 2026 | September 15, 2026 |
| Q4 2026 | Sep 1 – Dec 31, 2026 | January 15, 2027 |
The quarters are not equal in length. Q2 is only two months. This is a long-standing IRS quirk that catches new filers off guard every year.
Both corporations and pass-through owners — but the thresholds differ.
A C-corporation expecting to owe $500 or more in federal tax for the year files Form 1120-W and pays quarterly. Most active C-corps fall into this bucket. Payments are made through EFTPS, which is mandatory for corporations.
S-corp shareholders, partners, LLC members, and sole proprietors expecting to owe $1,000 or more on their personal return file Form 1040-ES. The business itself does not pay; the owner pays from their personal cash. Payments can be made through IRS Direct Pay or EFTPS.
The IRS gives you a way to avoid underpayment penalties without forecasting current-year income perfectly. Pay either 100% of last year's total tax (110% if last year's AGI was over $150,000) or 90% of this year's actual tax — whichever is lower. Divide by four, pay one installment each quarter, done.
This is why a recurring reminder makes sense even if your income is variable. You do not need to recalculate every quarter. Pull last year's tax, divide by four, set a repeating reminder for the four dates, pay the same amount each time.
Quarterly estimated tax is the textbook case for a reminder system. The date is fixed but distant. The task takes 10 minutes once you have the number. The penalty for missing is small per quarter but real, and it compounds across the year. And the dates do not match natural calendar boundaries (June 15, not June 30; September 15, not September 30), so they are easy to slip past.
Set the reminder for two weeks before each quarter's due date. That gives you time to check your books, make the payment through EFTPS or IRS Direct Pay, and confirm the confirmation number lands in your records. See the corporate tax filing reminder for setting up the annual deadline as a separate reminder.
For the 2026 tax year, the four quarterly estimated payment dates are April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027. The dates are the same for C-corp 1120-W payments and for individuals using Form 1040-ES.
C-corporations that expect to owe more than $500 in tax for the year file Form 1120-W estimated payments. Sole proprietors, S-corp shareholders, partners, and LLC members who expect to owe more than $1,000 on their personal returns pay using Form 1040-ES. Both groups face an underpayment penalty if they fall short of safe-harbor thresholds.
The IRS charges an underpayment penalty calculated at the federal short-term rate plus 3%, currently around 8% annually. It is computed quarter by quarter, so paying late or short in any quarter accrues the penalty even if you catch up later in the year. Form 2210 (individuals) or Form 2220 (corporations) reconciles the math.
No underpayment penalty applies if you pay at least 100% of last year's total tax (110% if AGI was over $150,000) or 90% of this year's actual tax, whichever is less. Paying the safe-harbor amount in four equal quarterly installments is the simplest way to stay protected.
Yes. The IRS only requires that you have paid the cumulative amount by each due date. Paying the full year's estimate by April 15 satisfies all four deadlines. Some business owners do this to avoid the recurring mental load of remembering each quarter.
The penalty is small relative to annual filing penalties, but it compounds across the year. The fix is to pay the missed installment plus any catch-up immediately. The IRS will calculate the underpayment penalty when you file the annual return, so paying late reduces the penalty but does not eliminate it entirely.
Free. No account. Get an email two weeks before each of the four quarterly deadlines, plus follow-ups until you mark the payment made.
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