Quarterly Estimated Tax Calculator
If you earn income that is not subject to withholding, such as self-employment, freelance, or investment income, the IRS expects you to pay tax in four quarterly installments. This calculator applies the safe-harbor rule: it compares the amount needed to cover 90% of your expected current-year tax against the amount needed to cover your prior-year tax (100%, or 110% if your prior-year adjusted gross income exceeded 150,000 US dollars), takes the smaller required total, subtracts tax already withheld, and divides the remainder into four equal payments. Enter your figures to see your estimated quarterly amount and whether you are even required to pay.
Estimated tax formula
Current-year target = 0.90 * expected current tax
Safe-harbor factor = 1.10 if prior AGI over 150,000, else 1.00
Prior-year target = factor * prior-year tax
Required annual = min(current-year target, prior-year target) - withholding
Each quarter = required annual / 4
If required annual is at or below zero, no estimated payment is needed because withholding already meets the safe harbor. You generally must pay estimates if you expect to owe 1,000 US dollars or more at filing.
US estimated tax context
- The safe harbor avoids the underpayment penalty even if you ultimately owe more at filing time.
- The 110% prior-year factor applies when prior-year adjusted gross income exceeded 150,000 US dollars (75,000 if married filing separately).
- Estimated payments are generally due April 15, June 15, September 15, and the following January 15 for calendar-year filers.
- Self-employment tax (Social Security and Medicare) is part of your total tax and must be included in the expected current-year figure.
- This tool models the regular equal-installment method; uneven income may allow the annualized method instead.
Estimated tax: frequently asked questions
How does the IRS safe-harbor rule work?
You generally avoid an underpayment penalty if your withholding plus estimated payments cover at least 90% of the current year tax, or 100% of the prior year tax (110% if your prior-year adjusted gross income was over 150,000 US dollars). This calculator uses the smaller of your required current-year amount and your safe-harbor prior-year amount, then subtracts withholding.
When are quarterly estimated taxes due?
Federal estimated tax for a calendar-year filer is generally due in four installments: April 15, June 15, September 15, and January 15 of the following year. If a due date falls on a weekend or legal holiday, it shifts to the next business day. Always confirm dates on the IRS estimated taxes page.
Who needs to pay estimated taxes?
Generally you must pay estimated tax if you expect to owe 1,000 US dollars or more when you file, after subtracting withholding and refundable credits. This commonly affects self-employed people, freelancers, investors, and those with substantial 1099 income without enough withholding.
Is each quarterly payment the same amount?
Under the regular installment method, the four payments are equal (one quarter each). This calculator divides the annual required payment by four. If your income is uneven across the year, the IRS annualized income installment method may lower early payments; that is a separate calculation.
Does this replace IRS Form 1040-ES?
No. This is an estimate to help you plan. The authoritative worksheet is in IRS Form 1040-ES. Your final liability depends on deductions, credits, and self-employment tax that this simplified tool does not model in full.
Official sources
- Internal Revenue Service: Estimated Taxes.
- Internal Revenue Service: IRS home (Form 1040-ES and worksheets).
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.