Quarterly Estimated Tax Calculator
Turn "how much do I send the IRS?" into four numbers and four dates — hit the safe harbor and you cannot owe an underpayment penalty.
Written by Dorothy Ibrahim, 10+ years in banking & finance
Reviewed by Benton Jona, EA (Enrolled Agent) — 2026-07-13
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How we calculate this
This calculator turns "how much do I send the IRS?" into a per-quarter payment and the actual due dates. It targets the safe harbor from IRS Form 2210: pay the smaller of 90% of this year's expected tax or 100% of last year's tax (110% if your prior-year AGI topped $150,000), and you cannot owe an underpayment penalty — even if your final bill turns out higher. It also applies the $1,000 de minimis rule, under which no estimated payments are required at all.
The formulas
- Safe-harbor target
- the smaller of: 90% × expected current-year tax, or 100% × prior-year tax (110% if prior-year AGI was over $150,000; $75,000 married filing separately)With no prior-year tax on record (first year filing), only the 90%-of-current basis is available.
- Remaining to pay
- max(0, safe-harbor target − estimated tax paid so far)
- Payment per remaining quarter
- remaining to pay ÷ quarterly due dates remaining
- De minimis test
- if expected tax − paid so far is under $1,000, no estimated payments are required and no underpayment penalty applies
Worked example
- Take the defaults: $28,000 expected tax this year, $24,000 of tax last year, prior-year AGI under $150,000, nothing paid yet, all four 2026 quarters remaining.
- The current-year basis is 90% × $28,000 = $25,200. The prior-year basis is 100% × $24,000 = $24,000.
- The safe harbor is the smaller of the two: $24,000.
- Nothing has been paid, so $24,000 ÷ 4 quarters = $6,000 per quarter.
- Pay $6,000 by each 2026 due date — April 15, June 15, September 15, 2026 and January 15, 2027 — and no underpayment penalty can apply, even if you end up owing the extra $4,000 in April.
Rates, benchmarks & sources
- Safe-harbor percentages (90% current / 100% prior / 110% high-income), the $150,000 AGI trigger, the $1,000 de minimis rule, and the quarterly due dates (2026: Apr 15, Jun 15, Sep 15, 2026 and Jan 15, 2027) — IRS Pub 505/509, Form 2210
- Current IRS underpayment interest rate (7% for 2026 Q3) used in the missed-quarter warning — Rev. Rul. 2026-10
Figures current as of 2026-07-02. See our methodology & editorial standards for how constants are versioned and verified.
What this tool doesn’t model
- Federal only — most states run their own estimated-tax systems with different safe harbors and due dates; state payments are not modeled.
- The tool divides the remaining balance evenly across remaining quarters; the IRS technically expects payments in four equal installments from Q1, so catching up late can still leave penalty exposure for the early quarters (Form 2210 handles that math).
- It does not model the annualized-income installment method, which can lower required payments for seasonal or back-loaded income.
- Withholding from a W-2 job counts toward the safe harbor and is treated as paid evenly through the year — enter it in "paid so far," but the timing nuance is not modeled.
- This is a planning estimate, not filing advice — it does not compute your actual tax; pair it with the Business Income Tax estimator for that number.
Frequently asked questions
What exactly is the safe harbor?
It is the payment floor in IRS Form 2210 that shields you from the underpayment penalty. Pay at least 90% of this year's tax or 100% of last year's (110% if prior-year AGI exceeded $150,000) through timely quarterly payments, and the IRS cannot charge an underpayment penalty regardless of what you owe at filing. You still pay the balance in April — the safe harbor only protects you from the penalty.
Which basis should I aim for — 90% of this year or 100% of last year?
The tool automatically uses whichever is smaller, since both fully protect you. Prior-year tax is a known number, so many owners prefer it for certainty; the 90%-of-current basis wins when income is falling. If your prior-year AGI was over $150,000 the prior-year basis rises to 110%, which often flips the answer toward the current-year basis.
What happens if I already missed a quarter?
Underpayment interest accrues on the shortfall from that quarter's due date until you catch up — at 7%/yr as of 2026 Q3 (Rev. Rul. 2026-10). The penalty is computed per quarter, so paying as soon as possible stops the accrual; it does not retroactively erase what has already accrued. The Tax Penalty & Interest tool covers late filing and payment of the return itself.
Does this include state estimated taxes?
No — this covers federal estimated payments only. Most states with an income tax require their own estimated payments, with their own safe-harbor rules and due dates that do not always match the federal calendar. Check your state revenue department, and treat this tool as an estimate rather than filing advice.
I just started my business this year — what do I pay, and what if I don’t know my expected tax?
With no prior-year tax liability, the prior-year safe harbor is unavailable, so the tool targets 90% of your expected current-year tax. If you don’t know that number yet, turn on "Estimate it from net profit" and enter your expected net self-employment profit, filing status, and an optional flat state rate — the tool runs the same Schedule SE + income-tax engine as our take-home and effective-rate calculators (self-employment tax, standard deduction, simplified QBI) to derive the tax, then schedules it. Since a first year is hard to forecast, re-run the estimate each quarter as real numbers come in; it recalculates per remaining quarter automatically.
Why does it say I owe nothing quarterly?
If your expected balance due after withholding and payments is under $1,000, the de minimis rule applies: the IRS does not require estimated payments and no underpayment penalty can be assessed. You simply settle the balance when you file. The tool shows this as a "no penalty exposure" verdict rather than a $0 schedule you have to track.
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Federal figures only unless noted. State taxes vary.