US Quarterly Estimated Tax Calculator

Anyone who expects to owe $1,000 or more in federal tax for the year after subtracting withholding and refundable credits — typically the self-employed, freelancers, 1099 contractors, and anyone with significant investment, rental or business income that isn't covered by paycheck withholding.

You avoid an underpayment penalty if, through withholding plus timely estimated payments, you pay at least the lesser of 90% of your current-year tax, or 100% of your prior-year tax (110% if your prior-year adjusted gross income was over $150,000, or $75,000 if married filing separately).

April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027. If a due date falls on a weekend or holiday, it moves to the next business day.

Form 1040-ES is the IRS worksheet and payment voucher used to calculate and pay estimated tax. You don't file it with your tax return — you use the worksheet to work out your payment, then pay via IRS Direct Pay, EFTPS, the IRS2Go app, or by mailing a check with the voucher.

Yes. The $1,000 threshold, quarterly deadlines, and safe harbor rules apply identically whether you live in the US or abroad. Many Americans abroad reduce their US liability below the threshold using the Foreign Earned Income Exclusion or Foreign Tax Credit, but if you owe $1,000 or more after those reliefs, the same quarterly rules apply.

It can reduce or eliminate the income-tax portion, but not necessarily self-employment tax — the FEIE does not exclude income from the 15.3% self-employment tax, so self-employed Americans abroad can still owe substantial estimated tax even with no US income tax due.

If you had no US tax liability last year (and were a US citizen or resident for the whole year), the 100%/110% prior-year safe harbor doesn't apply — you generally only need to pay 90% of your current-year tax to avoid a penalty, or you can rely on it being under the $1,000 threshold.

Your adjusted gross income from your prior-year federal return (Form 1040, line 11). If that figure was over $150,000 ($75,000 if married filing separately), you need to pay 110% of prior-year tax rather than 100% to qualify for the prior-year safe harbor.

You can, but it isn't always optimal — the safe harbor rule lets you pay the lesser of the 90%-current-year or 100%/110%-prior-year figures, which is sometimes well below a naive quarter-of-expected-tax split, especially if this year's income is unusually high compared to last year.

The IRS calculates an underpayment penalty (effectively interest, at a rate set quarterly) on the shortfall for each period it was outstanding, using Form 2210. Paying late is better than not paying at all, but the penalty clock runs from each quarterly due date, not just from the annual filing deadline.

Yes. Withholding is treated as if it were paid evenly throughout the year regardless of when it was actually withheld, which is why increasing W-2 withholding late in the year is a common technique to fix an estimated-tax shortfall without a formal quarterly payment.

Start from your expected net self-employment profit, add self-employment tax (15.3% on net earnings up to the Social Security wage base, $184,500 for 2026, plus 2.9% Medicare with no cap), then add income tax on the total using your marginal bracket. If last year you were a W-2 employee with little tax due, the prior-year safe harbor may be very low — check the 90%-of-current-year figure carefully instead.

Most states with an income tax have their own separate estimated payment system, deadlines and safe harbor thresholds, which often differ from the federal rules. This calculator covers federal estimated tax only — check your state revenue department for state-specific rules.

Overpayments are refunded (or can be applied to next year's first-quarter payment) when you file your annual return, the same as excess withholding. There's no separate penalty for overpaying, only for underpaying below the safe harbor target.

Yes — recalculate each quarter as your actual income becomes clearer, using the annualized income installment method (Schedule AI on Form 2210) if your income is uneven across the year, which can reduce or eliminate a penalty even if your total annual payments are below a flat safe harbor target.

No. Self-employment tax (Social Security and Medicare on net self-employment earnings) is one component of your total tax liability. Estimated tax payments cover your entire expected federal tax bill for the year — income tax plus self-employment tax plus any other applicable taxes — not self-employment tax alone.

It applies the exact 2026 IRS safe harbor percentages (90% current-year, 100%/110% prior-year) once you supply your own estimate of current-year tax. It is only as accurate as the current-year tax figure you enter, so revisit it if your income changes significantly during the year.

Yes — the federal safe harbor rule applies to US citizens and Green Card holders in the UK exactly as it does domestically. What differs is the underlying tax estimate itself, since Foreign Tax Credit and FEIE calculations, and UK tax-year timing mismatches, can make current-year US tax harder to predict early in the year.

The calculation runs entirely in your browser and nothing is stored unless you choose to download the branded PDF report, at which point you provide your name and email so we can send it. Phone and address are optional.

Yes. Enter your name and email (phone and address optional) and we generate a TaxStone-branded PDF of your estimated tax breakdown to download instantly — useful for budgeting each quarter or sharing with your accountant.

If your income is self-employed, cross-border, or varies significantly quarter to quarter, a review can prevent both overpaying unnecessarily and underpayment penalties. Book a free 20-minute call with a TaxStone Enrolled Agent to check your position.