How do I calculate quarterly estimated taxes?

Project your income for the year, work out the total tax on it — income tax plus self-employment tax and any Net Investment Income Tax — subtract expected withholding and credits, then divide the remainder across the four payment deadlines. If your income is uneven, use the Form 2210 Schedule AI annualized method instead, which sizes each installment to the income you had actually earned by that date.

Who has to pay quarterly estimated taxes?

Anyone who expects to owe at least $1,000 in tax for the year after withholding and refundable credits. In practice that means freelancers, contractors and the self-employed, investors with significant gains or dividends, retirees taking distributions without withholding, and employees whose withholding does not cover a large bonus, RSU vest or side income.

What is the estimated tax safe harbor?

A payment level that protects you from the underpayment penalty regardless of your final bill. You are safe if you pay at least 90% of this year’s tax, or 100% of last year’s total tax — 110% if your prior-year adjusted gross income was over $150,000 ($75,000 if married filing separately).

When are quarterly estimated taxes due?

April 15, June 15, September 15 and January 15 of the following year, shifting to the next business day when a date falls on a weekend or legal holiday. For the 2026 tax year the dates are April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027.

What is the annualized income installment method?

It is the alternative to paying four equal installments, set out on Schedule AI of IRS Form 2210. Each installment is recalculated from the income you actually earned through that period, so a quarter in which you earned little does not generate a payment — or a penalty — based on income that arrived later in the year.

Is this estimated tax calculator free?

Yes. The calculator is free with no sign-up required, and the calculations run in your browser. Creating an account is optional and only exists to save your figures across devices.

Which tax years does the calculator support?

The 2024, 2025 and 2026 tax years, using each year’s own standard deduction, tax brackets, long-term capital gains thresholds and Social Security wage base.

No sign-up required

Free quarterly estimated tax calculator

Work out what to pay the IRS this quarter — with full support for IRS Form 2210 Schedule AI, the Annualized Income Installment Method.

Built for freelancers, 1099 contractors, investors and high-income earners whose income does not arrive in four equal pieces. Calculates income tax, self-employment tax, capital gains, the Net Investment Income Tax and safe harbor — and shows the full step-by-step math, not just a number.

Calculate my quarterly payment →

By continuing, you agree to the legal disclaimer below. This tool does not constitute tax advice.

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Schedule AI support

Full IRS Annualized Income Installment Method. Not buried inside a $100 filing suite — just the calculator you need.

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Full math transparency

Shows every step of the Form 2210 calculation so you can verify the math and understand exactly what you owe.

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Instant, in-browser

All calculations run locally in your browser. No data sent to any server. No sign-up. No subscription.

Who is this for?

→Investors with lumpy capital gains — a big year-end sale or RSU vest
→Freelancers, consultants and 1099 contractors with variable quarterly income
→Self-employed filers who owe self-employment tax on top of income tax
→High-income earners who get hit with Net Investment Income Tax or Additional Medicare Tax
→Anyone who wants to avoid estimated tax penalties without overpaying each quarter

What the calculator covers

Enter what you have earned so far and the calculator works out the quarterly payment due, using either equal installments or the annualized method. It applies each tax year's own figures: the standard deduction, the ordinary income brackets, the long-term capital gains thresholds and the Social Security wage base for 2024, 2025 and 2026.

· Federal income tax on ordinary income
· Long-term capital gains and qualified dividends
· Self-employment tax (15.3%) and its deductible half
· Net Investment Income Tax (3.8%)
· Additional Medicare Tax (0.9%)
· Standard or itemized deductions
· Safe harbor tests: 90% current year, 100% / 110% prior year
· Withholding and payments already made

Calculators by tax year

Each year's own brackets, standard deduction, capital gains thresholds and payment deadlines, with the calculator set to that year.

Annualized income installment method calculator →

Estimated tax guides

Plain-English explanations of the rules the calculator applies.

IRS Form 2210 Schedule AI: the Annualized Income Installment Method explained
What Form 2210 Schedule AI does, who should use the annualized income installment method, and how the four annualization periods and 22.5% / 45% / 67.5% / 90% installment thresholds work.
Estimated tax safe harbor rules: the 90%, 100% and 110% tests
The two estimated tax safe harbors — 90% of this year’s tax, or 100% of last year’s (110% if your prior-year AGI was over $150,000) — and which one costs you less.
Quarterly estimated tax due dates for 2024, 2025 and 2026
Every quarterly estimated tax payment deadline for the 2024, 2025 and 2026 tax years, including the weekend and holiday shifts, plus the income period each payment covers.
The IRS estimated tax underpayment penalty: how it is calculated
How the underpayment penalty is charged quarter by quarter at the IRS interest rate, the $1,000 de minimis exception, and the ways to reduce or remove it on Form 2210.
Self-employment tax and quarterly estimated payments
How the 15.3% self-employment tax works for freelancers and 1099 contractors, the Social Security wage base, the 92.35% net earnings factor, and how it feeds your quarterly estimates.
Estimated taxes on capital gains, RSUs and other lumpy income
What to pay, and when, after a large stock sale or RSU vest — long-term capital gains rates, the 3.8% Net Investment Income Tax, and why annualizing usually beats equal installments.

Browse all guides →

Frequently asked questions about estimated taxes

How do I calculate quarterly estimated taxes?: Project your income for the year, work out the total tax on it — income tax plus self-employment tax and any Net Investment Income Tax — subtract expected withholding and credits, then divide the remainder across the four payment deadlines. If your income is uneven, use the Form 2210 Schedule AI annualized method instead, which sizes each installment to the income you had actually earned by that date.
Who has to pay quarterly estimated taxes?: Anyone who expects to owe at least $1,000 in tax for the year after withholding and refundable credits. In practice that means freelancers, contractors and the self-employed, investors with significant gains or dividends, retirees taking distributions without withholding, and employees whose withholding does not cover a large bonus, RSU vest or side income.
What is the estimated tax safe harbor?: A payment level that protects you from the underpayment penalty regardless of your final bill. You are safe if you pay at least 90% of this year’s tax, or 100% of last year’s total tax — 110% if your prior-year adjusted gross income was over $150,000 ($75,000 if married filing separately).
When are quarterly estimated taxes due?: April 15, June 15, September 15 and January 15 of the following year, shifting to the next business day when a date falls on a weekend or legal holiday. For the 2026 tax year the dates are April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027.
What is the annualized income installment method?: It is the alternative to paying four equal installments, set out on Schedule AI of IRS Form 2210. Each installment is recalculated from the income you actually earned through that period, so a quarter in which you earned little does not generate a payment — or a penalty — based on income that arrived later in the year.
Is this estimated tax calculator free?: Yes. The calculator is free with no sign-up required, and the calculations run in your browser. Creating an account is optional and only exists to save your figures across devices.
Which tax years does the calculator support?: The 2024, 2025 and 2026 tax years, using each year’s own standard deduction, tax brackets, long-term capital gains thresholds and Social Security wage base.