What is Quarterly Estimated Tax Calculator (Form 1040-ES)?
Free Form 1040-ES quarterly estimated tax calculator with the IRS safe-harbor rule (90% current OR 100/110% prior year) per IRC § 6654. Shows quarterly payment amount, due dates, and underpayment-penalty risk flag. No signup required.
Quarterly Est runs entirely in your browser using JavaScript (browser). Your data never leaves your device.
Free Quarterly Estimated Tax Calculator (Form 1040-ES)
Project your annual federal tax bill (income tax + SE tax), compute the IRC § 6654 safe-harbor floor (90% current OR 100/110% prior year — 110% above $150k AGI), and get the suggested quarterly 1040-ES payment to avoid the underpayment penalty. All four due dates (4/15, 6/15, 9/15, 1/15 per § 6654(c)) included.
This year (projected)
Last year (for safe harbor)
If prior-year AGI > $150k, the safe-harbor floor uses 110% of prior tax; otherwise 100%.
Per quarter
$750
x 4 = $3,000 remaining for the year.
Underpayment risk
You're below the safe-harbor floor. Without estimated payments, you'll likely owe the IRS § 6654 underpayment penalty.
Due dates
Q1: April 15, 2026
Q2: June 15, 2026
Q3: September 15, 2026
Q4: January 15, 2027
Per quarter
$750
Per quarter
$750
Risk
Underpaying
The IRS § 6654 safe harbor — what it actually says
The IRS expects taxes to be paid as income is earned, not in one big April check. For salaried W-2 employees, this happens automatically through payroll withholding. For freelancers, business owners, investors with significant non-wage income, and anyone with a tax bill above ~$1,000 not covered by withholding, you must send quarterly estimated payments via Form 1040-ES — or pay an underpayment penalty under IRC § 6654.
The safe-harbor rule (IRC § 6654(d)(1)) waives the penalty if your total payments through the year cover at least the LESSER of:
- 90% of your current year's total tax — but you don't know this exactly until year-end, so it's a moving target.
- 100% of your prior year's total tax — the "look-back" safe harbor. Or 110% if your prior-year AGI exceeded $150,000 (IRC § 6654(d)(1)(C)).
The prior-year safe harbor is the easier number to hit because you know it exactly. For most people, the cleanest strategy is: target 110% (or 100%) of prior-year tax via withholding + 1040-ES through the year. If your current-year income jumps significantly, top up Q4 to land at 90% of current-year tax instead.
Due dates (IRC § 6654(c))
- Q1 — April 15 — covers Jan–Mar income
- Q2 — June 15 — covers Apr–May income (yes, only 2 months — IRS scheduling quirk)
- Q3 — September 15 — covers Jun–Aug income
- Q4 — January 15 of the following year — covers Sep–Dec income
Miss a quarterly deadline by more than a few days and the penalty accrues interest at the federal short-term rate + 3% (annualized) on the underpayment from the due date until paid.
Common quarterly-estimate mistakes
- Forgetting Q2 is only 2 months in. Many freelancers expect quarterly to mean "every 3 months." It doesn't — June 15 lands 2 months after Q1, not 3.
- Not adjusting for an income spike. Hit a $200k year after $80k prior years? The 110% × $12k prior safe harbor only covers $13,200 — but your actual tax on $200k might be $45,000. Top up Q3 and Q4 or pay the penalty on the gap.
- Trying to use the annualized-income exception every year. The annualized-income method (Form 2210 Schedule AI) lets uneven earners pay more in later quarters when income arrives later. It works but is paperwork-heavy. The standard approach (equal quarterly payments based on prior-year safe harbor) is much simpler.
- Treating estimated payments as discretionary. Some freelancers skip Q1 and Q2 thinking they'll "true up" at April. The penalty starts the day each quarter is late — paying the full balance in April doesn't cure the Q1/Q2/Q3 underpayment.
- Forgetting state estimates. Most states with income tax (CA, NY, NJ, IL, etc.) have their own quarterly schedule, sometimes aligned with federal and sometimes off. Add state estimates to your calendar.
Frequently Asked Questions
Who has to pay quarterly estimated taxes?+
Anyone whose total tax owed exceeds $1,000 after withholding (IRC § 6654(e)(1)) needs to make estimated payments. This typically catches self-employed people, freelancers, contractors, retirees with non-wage income, anyone with significant investment income, and W-2 employees whose withholding doesn't cover their actual liability (RSU recipients, side-hustlers, etc.).
What's the safe harbor?+
IRC § 6654(d)(1) waives the underpayment penalty if your total payments cover the LESSER of: 90% of current-year tax, OR 100% of prior-year tax (110% if prior-year AGI > $150k under § 6654(d)(1)(C)). The prior-year safe harbor is the easier number to hit because you know it exactly.
What are the due dates?+
Q1: April 15 (covers Jan–Mar), Q2: June 15 (Apr–May, only 2 months after Q1), Q3: September 15 (Jun–Aug), Q4: January 15 of following year (Sep–Dec). Per IRC § 6654(c)(2). Federal holidays and weekends push the deadline to the next business day.
What's the underpayment penalty?+
Interest at the federal short-term rate + 3% (annualized), applied to each quarter's underpayment from the due date until paid. Typical penalty for someone $10,000 short for the year: ~$300–500 depending on when shortages occurred. Not enormous, but avoidable.
Can I pay it all in Q4?+
Technically yes, but you'll owe the penalty on Q1, Q2, and Q3 underpayments. The penalty assumes income arrived evenly through the year unless you file Form 2210 Schedule AI (annualized-income method) showing it arrived later. If your income IS heavily back-loaded (e.g. a Q4 RSU vest), Schedule AI can eliminate the penalty.
Should I increase withholding instead?+
Yes, when possible. Withholding from a W-2 paycheck is treated as paid evenly through the year (IRC § 6654(g)) — even if it all comes from a Q4 paycheck. So if you have a W-2 job, increasing year-end withholding is a powerful tool to catch up on shortfalls without triggering Q1/Q2/Q3 penalties.
Do states have their own estimated taxes?+
Most states with income tax do (CA, NY, NJ, IL, MA, MN, etc.), with their own due dates (often aligned with federal but not always) and their own safe-harbor rules. Track state estimates separately. No-income-tax states (FL, TX, NV, WA, TN, NH-limited, SD, WY, AK) have no state-level requirement.
Is my data stored?+
No. All projections run in your browser. Your income, withholding, and prior-year tax never leave your device.
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